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Dr. Kennedy's Vocabulary Course: -I-
(View Course for 11/18/2013)
(A B C D E F G H I J K L M)
 
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Ron Kennedy, M.D.
 
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- I -
(A B C D E F G H I J K L M)
Iatrapistic:  A lack of faith in doctors. Entirely from the Greek: "iatr-" indicating a relationship to a physician or medicine + "a" meaning lack + "pisteuo" meaning I trust in.
Iatric:  Relating to medicine or a physician. Iatric systems are medical systems. From the Greek iatrikos (medical)), iatros (physician)
Iatrogenic:  Due to the action of a physician or a therapy the doctor prescibed
Iatromelia:  Ineffective or negligent medical treatment. From iatro meaning a relationship to a physician or medicine + the Greek meleos meaning fruitless or vain.
Iatromisia:  An intense dislike of doctors. From iatro indicating a relationship to a physician or medicine + the Greek miseo meaning I hate.
IBD (inflammatory bowel disease):   A group of chronic intestinal diseases characterized by inflammation of the bowel -- the large or small intestine. The most common types of inflammatory bowel disease are ulcerative colitis and Crohn's disease.
IBS (irritable bowel syndrome):  A common gastrointestinal disorder involving an abnormal condition of gut contractions (motility) characterized by abdominal pain, bloating, mucous in stools, and irregular bowel habits with alternating diarrhea and constipation, symptoms that tend to be chronic and to wax and wane over the years. Although IBS can cause chronic recurrent discomfort, it does not lead to any serious organ problems.
Ibuprofen:  A non-steroidal anti-inflammatory drug (NSAID) commonly used to treat pain, swelling, and fever. Common brand names for Ibuprofen include Advil, Motrin, and Nuprin.
ICD (Implantable Cardiac Defibrillator):  a device that is put within the body and is designed to recognize certain types of abnormal heart rhythms (arrhythmias) and correct them. Defibrillators continuously monitor the heart rhythm in order to detect overly rapid arrhythmias.
Ice cream headache:  A headache that occurs when one puts ice, a cold food or chilled beverage in the mouth. Ice cream is by far the most frequent offender. The headache occurs regardless of whether or not the individual suffers from other types of headache, such as migraine. Ice cream headache is characterized by a stabbing, aching pain that begins a few seconds after ingestion of something cold. The pain peaks in 30 to 60 seconds. It is usually located in the midfrontal area (in the middle of the forehead) but may be in the temporal or retro-orbital region (behind the eye). The headache may be accompanied by a toothache. The pain rarely lasts for more a few minutes, if that long.
Ichthyosis:  Dry, rectangular scales on the skin. Like fish scales. From the Greek "ichthys" meaning fish.
Ichthyosis simplex:  Excessively dry skin with scaling. Also called xeroderma.
Ichthyosis vulgaris:  A genetic skin disease that is characterized by scaly (fishlike) areas of skin. The first scaly skin problems usually appear after 3 months of age. The palms and soles are often affected. Areas that tend to be spared include the axillae (the armpits), the antecubital fossa (the inside area at the bend of the elbow) and the popliteal fossa (behind the knee). A significant proportion of people with this disease have asthma, eczema or hay fever.
ICSI:  Stands for intracytoplasmic sperm injection, a test-tube fertilization procedure in which a sperm is injected directly into an egg to achieve fertilization. ICSI is done for male infertility.
Icterus:  Jaundice. At least one medical dictionary defines icterus as the presence of jaundice seen in the sclera of the eye. This is incorrect. Icterus is synonymous with jaundice. They are one and the same thing.
ICU:  Intensive Care Unit.
ICU psychosis:  A disorder in which patients in an intensive care unit (ICU) or a similar hospital setting may experience anxiety, become paranoid, hear voices, see things that are not there, become severely disoriented in time and place, become very agitated, even violent, etc. The condition has been formally defined as "acute brain syndrome involving impaired intellectual functioning which occurs in patients who are being treated within a critical care unit." ICU psychosis is a form of delirium, or acute brain failure. Organic factors including dehydration, hypoxia (low blood oxygen), heart failure (inadequate cardiac output), infection and drugs can cause or contribute to delirium.
IDET:  Intradiskal electrothermal therapy, a procedure designed to relieve back pain due to damage to the disks between the spine bones. Under local anesthesia and X-ray guidance, a needle is introduced into the disk and a catheter with a heating coil is inserted through the needle. The tip of the catheter is then gradually heated to seal the breach in the collagen in the disk wall. The aim is to kill the tiny nerve endings that carry pain signals from the site and so relieve the pain. Following the procedure, the patient should be able to leave the hospital within two hours. To date this procedure has not been proven effective. I had it in 2000 and it was worthless.
Idiopathic:  Of unknown cause. Any disease that is of uncertain or unknown origin may be termed idiopathic
Idiopathy:  A disease or medical condition of unknown origin or which has no apparent cause. As in the idiopathy of cancer.
Idiot savant:  See: Autistic savant. The term "autistic savant" is more politically correct and less perjorative than the old term "idiot savant.
Ileal pouch:  A surgically created chamber made up of a portion of the lower part of the ileum, the last (lowest) part of the small intestine. The ileal pouch generally connects to the rectum with the muscles of this area left intact to allow continuation of bowel control. The ileal pouch acts as a reservoir with the goal being a return to regular bowel habits despite removal of the large intestine. Surgery to create an ileal pouch is usually done for patients who need a total colectomy (removal of the entire colon or large intestine, that part of the intestinal tract normally positioned between the ileum and the rectum). Patients with ulcerative colitis are the most common candidates for an ileal pouch.
Ileoscopy:  Use of a flexible instrument (a "scope") to examine the ileum which is the lowest part of the small intestine. Ileoscopy is usually accomplished during colonoscopy, when the instrument tip passes first through the rectum and the lower colon and eventually reaches the area where the ileum and the colon (the large bowel) connect. The examiner can look at the ileum and take biopsy samples of the lining tissues, if needed.
Ileostomy:  An opening into the ileum, part of the small intestine, from the outside of the body. An ileostomy provides a new path for waste material to leave the body after part of the intestine has been removed.
Ileum:  The lowest part of the small intestine, located beyond the duodenum and jejunum, just before the large intestine (the colon).
Ileus:  Obstruction of the intestine due to paralysis of the intestinal muscles. The paralysis does not need to be complete to cause ileus, but the intestinal muscles must be so inactive that it prevents the passage of food and leads to a functional blockage of the intestine.
Iliac horns:  Horn-like malformations of the crest of both iliac bones of the pelvis. A characteristic finding in the nail-patella syndrome.
Iliopsoas muscle:  A blending of two muscles (the iliacus and psoas major) that run from the lumbar portion of the vertebral column to the femur. The main action of the iliopsoas is to flex the thigh at the hip joint.
Ilium:  The upper part of the bony pelvis which forms the receptacle for the head of the femur at the hip joint.
Illusion:  A perception that occurs when a sensory stimulus is present but is incorrectly perceived and misinterpreted, such as hearing the wind as someone crying. Everyone may occasionally experience an illusion. However, illusions are extraordinarily common in people suffering from schizophrenia.
IM (intramuscular):  An IM medication is given by needle into the muscle. This is as opposed to a medication that is given by a needle, for example, into the skin (intradermal) or just below the skin (subcutaneous) or into a vein (intravenous).
Imagery:  Both a mental process (as in imagining) and a wide variety of procedures used in therapy to encourage changes in attitudes, behavior, or physiological reactions. As a mental process, it is often defined as "any thought representing a sensory quality." It includes, as well as the visual, all the senses - aural, tactile, olfactory, proprioceptive, and kinesthetic.
Imitrex:  Brand name for sumatriptan, a triptan drug for the treatment of migraine.
Immune:  Protected against infection. The Latin immunis means free, exempt.
Immune complex:  A cluster of interlocking antigens and antibodies forming a large network of molecules. Also called an antigen-antibody complex.
Immune response:  Any reaction by the immune system.
Immune system:  A complex system that is responsible for distinguishing us from everything foreign to us, and for protecting us against infections and foreign substances. The immune system works to seek and kill invaders.
Immune thrombocytopenic purpura:  A blood disorder characterized by the destruction of blood platelets due to the presence of antiplatelet autoantibodies. (Autoantibodies are antibodies directed against the patient's own cells, in this disorder, the patient's own platelets.) Thrombocytopenia refers to a decrease in platelets (also known as thrombocytes). Purpura pertains to the visible hallmarks: purplish areas in the skin and mucous membranes (such as the mouth lining) where bleeding has occurred as a result of decreased platelets.
Immune tolerance:  A state of unresponsiveness to a specific antigen or group of antigens to which a person is normally responsive. Immune tolerance is achieved under conditions that suppress the immune reaction and is not just the absence of a immune response. Immune tolerance can result from a number of causes including: (1) Prior contact with the same antigen in fetal life or in the newborn period when the immune system is not yet mature; (2) Prior contact with the antigen in extremely high or low doses; (3) Exposure to radiation, chemotherapy drugs, or other agents that impair the immune system; (4) Heritable diseases of the immune system; (5) Acquired diseases of the immune system such as HIV/AIDS. Immune tolerance can be defined as a state in which a T cell can no longer respond to antigen. The T cell "tolerates" the antigen.
Immunity:  The condition of being impervious to infectious disease. Immunity can be innate (for example, humans are innately immune to canine distemper) or conferred by a previous infection or immunization.
Immunization:  The act of bolstering the immune system against a specific disease. An example of man made immunization is vaccination. Immunization stimulates the immune system, the natural disease-fighting system of the body. The healthy immune system is able to recognize invading bacteria and viruses and produce substances (antibodies) to destroy or disable them. Immunizations prepare the immune system to ward off a disease. To immunize against viral diseases, the virus used in the vaccine is weakened or killed. To immunize against bacterial diseases, it is generally possible to use only a small portion of the dead bacteria to stimulate the formation of antibodies against the whole bacteria. In addition to the initial immunization process, it has been found that the effectiveness of immunizations can be improved by periodic repeat injections or "boosters." Natural immunization occurs progressively throughout life as the organism encounters antigens of various kinds.
Immunocompetence:  The ability to produce a normal immune response.
Immunocompetent:  Able to develop an immune response. Able to recognize antigens and respond to them.
Immunocompromised:  The condition of an immune system impaired by disease or treatment.
Immunocow:  A cow that has been genetically engineered to produce human antibodies. An immunocow, when challenged with an infectious agent, can produce large volumes of human antibodies against that agent. There are also immunopigs and presumably immunogoats, immunosheep, immunohorses, etc.
Immunodeficiency:   Inability to mount a normal immune response. Immunodeficiency can be due to a genetic disease or acquired as in AIDS due to HIV.
Immunodeficient:  Lacking immunity and so susceptible to infection.
Immunodepressant:  An agent that can depress or prevent the immune response.
Immunogenetics:  The genetics (inheritance) of the immune response. For example, the study of the Rh, ABO and other blood groups or the HLA system important to kidney and other transplants.
Immunoglobulin:  A protein produced by plasma cells and lymphocytes and characteristic of these types of cells. Immunoglobulins play an essential role in the body's immune system. They attach to foreign substances, such as bacteria, and assist in destroying them. Immunoglobulin is abbreviated Ig.
Immunoglobulin A:  Abbreviated IgA. A major class of immunoglobulins found in serum and external body secretions such as saliva, tears, and sweat as well as in the gastrointestinal, respiratory, and genitourinary tracts.
Immunoglobulin D:  Abbreviated IgD. A class of immunoglobulins found as antibodies on the surface of B cells (B lymphocytes). Almost nothing is known about the normal function of IgD.
Immunoglobulin E:  Abbreviated IgE. A class of immunoglobulins that includes the antibodies elicited by an allergic substance (allergen). A person who has an allergy usually has elevated blood levels of IgE. IgE antibodies attack and engage the invading army of allergens.
Immunoglobulin G:  Abbreviated IgG. A major class of immunoglobulins found in the blood, including many of the most common antibodies circulating in the blood. Also known as gamma globulin.
Immunoglobulin M:  Abbreviated IgM. A major class of immunoglobulins. IgM includes the antibodies that are usually produced first in an immune response and are later replaced by other types of antibodies.
Immunologist:  A person who is knowledgeable about immunology.
Immunology:  The study of all aspects of the immune system including its structure and function, disorders of the immune system, blood banking, immunization and organ transplantation.
Immunosuppressant:  An agent that can suppress or prevent the immune response. Immunosuppressants are used to prevent rejection of a transplanted organ and to treat autoimmune diseases such as psoriasis, rheumatoid arthritis, and Crohn's disease. Some treatments for cancer act as immunosuppressants. Also called an immunodepressant.
Immunosuppression:  Suppression of the immune system. Immunosuppression may result from certain diseases such as AIDS or lymphoma or from certain drugs such as some of those used to treat cancer. Immunosuppression may also be deliberately induced with drugs, as in preparation for bone marrow or other organ transplantation to prevent the rejection of the transplant.
Immunotherapy:  Treatment to stimulate or restore the ability of the immune (defense) system to fight infection and disease. Biological therapy is thus any form of treatment that uses the body's natural abilities that constitute the immune system to fight infection and disease or to protect the body from some of the side effects of treatment. Immunotherapy (also called biological therapy or biotherapy) often employs substances called biological response modifiers (BRMs). The body normally produces low levels of BRMs in response to infection and disease. Large amounts of BRMs can be made in the laboratory to treat cancer, rheumatoid arthritis, and other diseases. Forms of biological therapy include monoclonal antibodies, interferon, interleukin-2 (IL-2), and several types of colony-stimulating factors (CSF, GM-CSF, G-CSF). Interleukin-2 and interferon are BRMs being tested for the treatment of advanced malignant melanoma. Interferon is a BRM now in use to treat hepatitis C. Biologic therapy to block the action of instruments of inflammation called tumor necrosis factor (TNF) is being explored to treat conditions such as Crohn's disease and rheumatoid arthritis. Etanercept (ENBREL) is a commercially available injectable TNF-blocking treatment for patients with severe rheumatoid arthritis. The side effects of biological therapy depend on the type of treatment. Often, these treatments cause flu-like symptoms such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Some patients develop a rash, and some bleed or bruise easily. In addition, interleukin therapy can cause swelling. Depending on how severe these problems are, patients may need to stay in the hospital during treatment. These side effects are usually short-term and they gradually go away after treatment stops.
Immunotherapy, allergy:  Stimulation of the immune system with gradually increasing doses of the substances to which a person is allergic, known colloquially as "allergy shots." The aim is to modify or stop the allergy by reducing the strength of the IgE response. This form of treatment is very effective for allergies to pollen, mites, animal dander, and especially stinging insects. Allergy immunotherapy usually takes six months to a year to become effective, and injections are usually required for three to five years.
Immunotoxin:  A hybrid molecule created by coupling an antibody or antigen with part or all of a toxin. The hybrid molecule combines the specificity of the antibody or antigen with the toxicity of the toxin. The possible targets of immunotoxins include cancer cells and cells containing HIV.
Impaction, dental:  Teeth pressing together. For example, molar teeth (the large teeth in the back of the jaw) can be impacted, cause pain and require pain medication, antibiotics, and surgical removal.
Impaired glucose tolerance:  A transition phase between normal glucose tolerance and diabetes, also referred to as prediabetes. In impaired glucose tolerance (IGT), the levels of blood glucose are between normal and diabetic. People with IGT do not have diabetes. Each year, only 1-5% of people whose test results show IGT actually develop diabetes. And with retesting, as many as half of the people with IGT have normal oral glucose tolerance test results. Weight loss and exercise may help people with IGT return their glucose levels to normal.
Imperforate anus:  A congenital malformation (a birth defect) in which the rectum is a blind alley (a cul-de-sac) and there is no anus. The anus is imperforate in the sense that the normal perforation we call the anus is absent. The end of the intestinal tract has not made its way through the skin in the perineal area. Imperforate anus occurs in 1 in about 5,000 newborn babies. It has to be corrected by surgery. Imperforate anus is also known as anal atresia.
Impetigo:  A bacterial skin infection caused by the staphylococcus or, more rarely,streptococcus bacteria. The first sign of impetigo is a patch of red, itchy skin. Pustules develop on this area, soon forming crusty, yellow-brown sores that can spread to cover entire areas of the face, arms, and other body parts. Most patients are children. Treatment is by antibiotics.
Implant:  1. To embed; to set in firmly. In embryology, the fertilized egg implants in the uterine lining 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted. 2. That which is embedded. For example: lens implants, breast implants, cochlear implants, defibrillator implants, pacemaker implants, etc.
Implantable cardiac defibrillator:  A device that is put within the body and is designed to recognize certain types of abnormal heart rhythms (arrhythmias) and correct them.
Implantation:  The act of setting in firmly. In embryology, implantation refers specifically to the attachment of the fertilized egg to the uterine lining, which occurs approximately 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted (embedded). There are breast implants, cochlear implants, defibrillator implants, pacemaker implants, etc.
Implicit memory:  Memory characterized by a lack of conscious awareness in the act of recollection. By contrast, explicit memory requires conscious recollection of previous experience. Implicit memory may survive largely unimpaired at the same time as a person's powers of explicit memory decline with age or are devastated in Alzheimer disease.
Impotence:  A common problem among men characterized by the consistent inability to sustain an erection sufficient for sexual intercourse or the inability to achieve ejaculation, or both. Impotence can vary. It can involve a total inability to achieve an erection or ejaculation, an inconsistent ability to do so, or a tendency to sustain only very brief erections.
Imprinting, genomic:  The phenomenon of parent-of-origin gene expression. The expression of a gene depends upon the parent who passed on the gene. For instance, two different disorders - Prader-Willi syndrome and Angelman syndrome - are due to deletion of the same part of chromosome 15. When the deletion involves the chromosome 15 that came from the father, the child has Prader-Willi syndrome, but when the deletion involves the chromosome 15 that came from the mother, the child has Angelman syndrome.
Imprinting, psychological:  A remarkable genetic phenomenon that occurs in animals, and theoretically humans, in the first hours of life. The newborn creature bonds to the type of animals it meets at birth, and begins to pattern its behavior after them. In humans, this is often called bonding and usually refers to the relationship between the newborn and its parents.
Impulsivity:  Inclined to act on impulse rather than thought. People who are overly impulsive, seem unable to curb their immediate reactions or think before they act. As a result, they may blurt out answers to questions or inappropriate comments, or run into the street without looking. Their impulsivity may make it hard for a child to wait for things they want or to take their turn in games.
In situ:  In the normal location. An "in situ" tumor is one that is confined to its site of origin and has not invaded neighboring tissue or gone elsewhere in the body. For example, squamous cell carcinoma in situ is an early stage of skin cancer.
In vitro:  Literally in glass, as in a test tube. A test that is performed in vitro is one that is done in glass or plastic vessels in the laboratory. In vitro is the opposite of in vivo (in a living organism).
In vitro fertilization (IVF):  a laboratory procedure in which sperm are placed with an unfertilized egg in a Petri dish to achieve fertilization. The embryo is then transferred into the uterus to begin a pregnancy or cryopreserved (frozen) for future use. IVF was originally devised to permit women with damaged or absent Fallopian tubes to have a baby.
In vivo:  In the living organism, as opposed to in vitro (in the "test tube").
In-the-canal hearing aid:  A hearing instrument custom designed to fit in the ear canal. It protrudes slightly into the outer ear and so is visible. In-the-canal (ITC) instruments are appropriate for mild to moderate hearing losses but not for infants or young children. President Ronald Regan wore such a device.
In-the-ear hearing aid:  A hearing instrument in a custom-made shell designed to fit in the outer ear and ear canal. An in-the-ear (ITE) aid may be suitable for mild to moderately severe hearing loss but not for infants or young children.
Inappropriate ADH secretion:  ADH, anti-diuretic hormone, is released by pituitary gland but made in the hypothalamus. ADH has an antidiuretic action; it suppresses the rate of urine production. (ADH is also known as vasopressin). Inappropriate secretion of ADH results in the inability to put out dilute urine, perturbs fluid and electrolyte balance, and causes nausea, vomiting, muscle cramps, confusion and convulsions. It may occur, for example, with oat-cell lung cancer, pancreatic cancer, prostate cancer, and Hodgkin's disease as well as a number of other disorders.
Inborn error of metabolism:  A heritable disorder of biochemistry. Examples of inborn errors of metabolism include albinism, cystinuria (a cause of kidney stones), phenylketonuria (PKU), and some forms of gout, sun sensitivity, and thyroid disease. These are only a very few of the hundreds of known inborn errors of metabolism.
Inbreeding:  The mating of two closely related persons. Also called consanguinity.
Inbreeding, coefficient of:  A measure of how close two people are genetically to each another. The coefficient of inbreeding, symbolized by the letter F, is the probability that a person with two identical genes received both genes from one ancestor. Take a first-cousin mating. First cousins share a set of grandparents. For any particular gene in the male, the chance that his female first cousin inherited the same gene from the same source is 1/8. Further, for any gene the man passes to his child, the chance is 1/8 that the woman has the same gene and ˝ that she transmits that gene to the child so 1/8 X ˝ = 1/16. Thus, a first-cousin marriage has a coefficient of inbreeding F =1/16. The added risks for the offspring of first cousins depend not only upon the coefficient of inbreeding but also upon the genetic family history and test results. For example, first cousins of Italian descent are at increased risk of carrying a gene for beta thalassemia and genetic laboratory tests may confirm that they are both beta-thalassemia gene carriers. There are always added risks in the mating of closely related persons.
Incest:  Sexual activity between individuals so closely related that marriage is prohibited. Incest involving a child is a form of child abuse.
Inch:  In length, 1/12th of foot or 1/36 of a yard or, metrically, 2.54 centimeters. The inch, along with the foot and yard, are Old World creations to which the USA has clung. The inch was originally about the length of the last bone (distal phalanx) in a man's thumb and served as a measurement of land. The etymology (word history) of "inch" is remarkable. It originally meant "one twelfth". The abbreviation is "in."
Incidence:  The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain d
Incision:  A surgical term for a cut.
Incisional biopsy:  A biopsy in which only a sample of the suspicious tissue is cut into (incised) and removed for purposes of diagnosis. A incisional biopsy is in contrast to an excisional biopsy in which an entire lesion, usually a tumor, is removed.
Incompetent cervix:  A cervix that is abnormally liable to dilate and so is not competent to keep the fetus up in the uterus and keep it from being spontaneously miscarried.
Incontinence:  Inability to control excretions. Urinary incontinence is inability to keep urine in the bladder. Fecal incontinence is inability to retain feces in the rectum.
Incontinent:  Unable to control excretions, to hold urine in the bladder or keep feces in the rectum. This is the usual medical meaning of the word incontinent. Incontinent can also refer to a lack of self-restraint in the sexual arena or failure to refrain from sexual intercourse.
Incontinentia pigmenti:  A genetic disease that begins soon after birth with the development of blisters on the trunk and limbs. These blisters then heal, but leave dark hyperpigmented streaks and marble-like whorls on the skin. Other key features include dental and nail abnormalities, bald patches and, in about one-third of cases, mental retardation.
Incubation period:  In medicine, the time from the moment of exposure to an infectious agent until signs and symptoms of the disease appear. For example, the incubation period of chickenpox is 14-16 days. In biology, the incubation period is the time needed for any particular process of development to take place. For example, the length of time for turtle eggs to hatch is the incubation period.
Incubator:  In biotechnology. an apparatus in which environmental conditions can be set and controlled. Incubators are used in microbiology for culturing (growing) bacteria and other microorganisms. Incubators in tissue culture rooms are used for culturing stem cells, lymphocytes, skin fibroblasts and other types of cells. And in the hospital nursery and newborn intensive care unit (NICU), incubators serve to house and maintain premature and ill infants
Incus:  One of the three tiny bones in the middle ear. Sound impulses coming from the eardrum are conveyed from the malleus to the incus and from the incus to the stapes (hammer-anvil-stirrup because they resemble these objects) at the oval window to the inner ear. Incus is Latin for anvil.
Index case:  A person who first draws attention to their family. For example, if my eye doctor discovers I have glaucoma and subsequently other cases of glaucoma are found in my family, I am the index case. Also called the propositus (if male) or proposita (if female).
Indication:  In medicine, a condition which makes a particular treatment or procedure advisable. For example high blood pressure is an indication for limiting salt in the diet.
Indifferent gonad:   In embryonic life, the gonad in males and females is initially identical. This gonad is said to be "indifferent" before it differentiates into a definitive testis or ovary.
Indirect immunofluorescence assay:  A laboratory test used to detect antibodies in serum or other body fluid. The specific antibodies are labeled with a compound that makes them glow an apple-green color when observed microscopically under ultraviolet light.
Indolent lymphoma:  A lymphoma that tends to grow and spread slowly, in contrast to an aggressive lymphoma which tends to grow and spread quickly. Indolent lymphomas include chronic lymphocytic lymphoma and follicular small cleaved cell lymphoma. Also called low-grade lymphoma.
Induced abortion::  An abortion that is brought about intentionally. Also called an artificial or therapeutic abortion, although many are not therapeutic, at least not from a health point of view. As opposed to a spontaneous abortion (a miscarriage).
Induced disease by proxy (aka Munchausen syndrome by proxy:  A parenting disorder in which the parent either fabricates an illness or induces an illness in their child. Munchausen syndrome by proxy (MSBP) differs from other forms of parenting disorder in that the offending parent is almost always the mother, she usually appears to be a model mother, there is little or no indication of family discord, and the abusive behavior is clearly premeditated, not impulsive, and not in reaction to the child's behavior.
Induced menopause:  Menopause induced by an unusual event, such as occurs when the ovaries are damaged by radiation, chemotherapy or other medications; or as occurs when the ovaries are surgically removed (by bilateral oophorectomy).
Induction therapy:  Treatment designed as a first step toward reducing the number of cancer cells. Often just referred to as induction.
Induration:  Localized hardening of soft tissue of the body. The area becomes firm, but not as hard as bone.
Industrial health:  A branch of public health concerned with the health and well-being of workers. Its aims are to eliminate hazards and reduce industrial fatigue in the workplace.
Indwelling catheter:  A flexible plastic tube (a catheter) inserted into the bladder that remains ("dwells") there to provide continuous urinary drainage.
Infant:  The word "infant" came from the Latin infans which was derived from in-, not + Fari, to speak = not to speak, speechless. So "infants" are "non-speakers."
Infant mortality rate:  The number of children dying under a year of age divided by the number of live births that year. The infant mortality rate is also called the infant death rate. The Infant mortality rate is widely used as the most meaningful index of the quality of a nation's health care system.
Infantile autism:  (Also called autism.) A spectrum of neuropsychiatric disorders characterized by deficits in social interaction and communication, and unusual and repetitive behavior. Some, but not all, people with autism are non-verbal. Autism is normally diagnosed before age six and may be diagnosed in infancy in some cases. The degree of autism varies from mild to severe in different children. Severely afflicted patients can appear profoundly retarded. The cause (or causes) of autism are not yet fully understood.
Infantile beriberi:  Disease in infants due to deficiency of thiamine. This disease is well-known in undeveloped countries among malnourished infants but it is very rare in developed countries. It can occur if a breastfeeding mother has an inadequate intake of thiamine. The disease can also occur in infants who are fed a formula containing insufficient thiamine, as happened tragically in 2003 in Israel.
Infantile genetic agranulocytosis:  Children born with this condition lack neutrophils (a type of white blood cell that is important in fighting infection). These children suffer frequent infections from bacteria which in the past led to death in three- quarters of cases before 3 years of age. This disease is also known as severe congenital neutropenia (SCN).
Infantile hypothyroidism:  Hypothyroidism (subnormal activity of the thyroid gland) that begins after birth and is manifest by features including delays in growth and development and myxedema surfacing during infancy. (Myxedema is a dry waxy type of swelling, often with swollen lips and nose. Infantile hypothyroidism is synonymous with infantile myxedema. Another name, now little used, for the condition is Brissaud's infantilism, after the French physician Edouard Brissaud (1852-1909).
Infantile myxedema:  Hypothyroidism (subnormal activity of the thyroid gland) that starts after birth and is manifest by features including delays in growth and development and myxedema surfacing during infancy. Myxedema is a dry waxy type of swelling, often with swollen lips and nose. Infantile myxedema is also called infantile hypothyroidism. Another name, now little used, for the condition is Brissaud's infantilism, after the French physician Edouard Brissaud (1852-1909).
Infantile paralysis (polio):  Infantile paralysis is an old synonym for poliomyelitis, an acute and sometimes devastating viral disease. Man is the only natural host for poliovirus. The virus enters the mouth and multiplies in lymphoid tissues in the pharynx and intestine. Small numbers of virus enter the blood and go to other sites where the virus multiplies more extensively. Another round of viremia (virus in the bloodstream) leads to invasion of the central nervous system (CNS), the spinal cord and brain, the only sites seriously struck by the virus. In polio, there is inflammation of the central nervous system, especially the anterior horn cells of the spinal cord and the brainstem (the portion of the brain between the cerebral hemispheres and spinal cord).
Infantile spasms:  A seizure disorder of infancy and early childhood with the onset predominantly in the first year of life of myoclonic seizures, hypsarrhythmia (abnormal, chaotic electroencephalogram), and mental retardation. The spasms are sudden, brief contractions of one or more muscle groups, and may be followed by a longer (less than 10 seconds) tonic phase. Most often the spasms occur in clusters during which the intensity or the frequency of the spasms may increase progressively to a peak, decline, or cease. The clusters tend to occur soon after arousal from sleep. They are not a feature of falling asleep. The spasms usually involve the muscles of the neck, trunk, and extremities. Neurological abnormalities other than seizures and retardation -- such as cerebral atrophy, congenital abnormalities and hydrocephalus -- are commonly reported among children with infantile spasms.
Infantile systemic hyalinosis:  A genetic disorder characterized at birth or soon afterwards by painful swollen joint contractures and red pigmentation over bony prominences. Pearly papules (little bumps) and fleshy nodules then develop in the skin. Overgrowth of the gums and thickened skin are also characteristic. Children with the disease are susceptible to infections and intractable diarrhea. Hyaline (glassy) material is deposited in many tissues including the skin, muscle, the heart, gastrointestinal tract, lymph nodes, spleen, thyroid, and adrenal glands. The disease is inherited in an autosomal recessive manner.
Infantile thiamine deficiency:  See: Infantile beriberi.
Infantile vitamin B1 deficiency:  See: Infantile beriberi.
Infarct:  An area of tissue death due to a local lack of oxygen. For example, in a myocardial infarction there is death of myocardial (heart muscle) tissue due to sudden (acute) deprivation of circulating blood. This is usually caused by arteriosclerosis with narrowing of the coronary arteries, the culminating event being a thrombosis (clot).
Infarction:  The formation of an infarct, an area of tissue death due to a local lack of oxygen.
Infection:  The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person. The term "infection" has some exceptions. For example, the normal growth of the usual bacterial flora in the intestinal tract is not usually considered an infection. The same consideration applies to the bacteria that normally inhabit the mouth.
Infectious hepatitis:  See Hepatitis A.
Infectious mononucleosis:  A specific viral infection (with the Epstein-Barr virus) in which there is an increase of white blood cells that are mononuclear (with a single nucleus) "Mono" and "kissing disease" are popular terms for this very common illness caused by the Epstein-Barr virus (EBV). By the time most people reach adulthood, an antibody against EBV can be detected in their blood meaning they have been infected with EBV. The illness is less severe in young children. The infection can be spread by saliva. The incubation period for infectious mononucleosis is 4 to 8 weeks. Symptoms include fever, fatigue, sore throat, and swollen lymph glands. "Mono" can cause liver inflammation (hepatitis) and spleen enlargement. Vigorous contact sports should be avoided to prevent spleen rupture.
Infectivity:  The proportion of persons exposed to an infectious agent who become infected by it.
Inferior:  In anatomy, below or toward the feet. As opposed to superior. For example the liver is inferior to the lungs.
Inferior vena cava:  A large vein that receives blood from the lower extremities, pelvis and abdomen and delivers it to the right atrium of the heart.
Inferolateral:  Below and to one side. Both inferior and lateral. In anatomy, there are many such compound terms
Infertile:  Not able to conceive after a year of regular intercourse without contraception.
Infertility:  The condition of being infertile, the diminished ability or the inability to conceive and have offspring. Infertility is also defined in specific terms as the failure to conceive after a year of regular intercourse without contraception. Infertility can be due to many causes. Studies have shown that a little more than half of cases of infertility are a result of female conditions. The remainder are caused by sperm disorders and by unexplained factors.
Infiltrate:  To penetrate. If an IV infiltrates, the IV fluid penetrates the surrounding tissue. When it is used as a noun, it is the fluid which has infiltrated under the skin.
Infiltrating ductal carcinoma of the breast:  One of several recognized specific patterns of cancer of the breast. It is so named because it begins in the cells forming the ducts of the breast. It is the most common form of breast cancer, comprising 65-85% of all cases. On a mammogram, invasive ductal carcinoma is usually visualized as a mass with fine spikes radiating from the edges (spiculation). It may also appear as a smooth edged lump in the breast. On physical examination, this lump usually feels much harder or firmer than benign causes of lumps in the breast. On microscopic examination, the cancerous cells invade and replace the normal breast tissue.
Infiltrating lobular carcinoma of the breast:  The second most common type of invasive breast cancer next to infiltrating ductal carcinoma, accounting for 5 to 10% of breast cancer. Infiltrating lobular carcinoma starts in the lobules, the glands that secrete milk, and then infiltrates surrounding tissue. On mammography, a lobular carcinoma can look similar to a ductal carcinoma -- a mass with fine spikes radiating from the edges (spiculation). However, on physical examination of the breast, a lobular carcinoma is usually not a hard mass like a ductal carcinoma but rather a vague thickening of the breast tissue. Lobular carcinoma can occur in more than one site in the breast (as a multicentric tumor) or in both breasts at the same time (as bilateral lobular carcinoma).
Inflammation:  A basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain. Inflammation is now recognized as a type of nonspecific immune response. The inflammatory response directs immune system components to the site of injury or infection and is manifest by increased blood supply and vascular permeability.
Inflammatory bowel disease (IBD):  A group of chronic intestinal diseases characterized by inflammation of the bowel -- the large or small intestine. The most common types of inflammatory bowel disease are ulcerative colitis and Crohn's disease.
Inflammatory response:  A fundamental type of response by the body to disease and injury, a response characterized by the classical signs of "dolor, calor, rubor, and tumor" -- pain, heat (localized warmth), redness, and swelling.
Influenza:  The flu is caused by viruses that infect the respiratory tract which are divided into three types, designated A, B, and C. Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia.
Infraspinatus muscle:  One of three muscles that assists the lifting of the arm while turning the arm outward (external rotation). The tendon of the infraspinatus muscle is one of four tendons that stabilize the shoulder joint and constitute the rotator cuff. Each of the four tendons that makes up the rotator cuff hooks up to a muscle that moves the shoulder in a specific direction.
Infuse:  In medicine, to introduce a solution into the body through a vein. An infusion is the therapeutic introduction of a fluid other than blood into a vein.
Ingrown toenail:  A common disorder that occurs when the edge of the toenail grows into the skin of the toe particularly on the big (great) toe. The corner of the nail curves down into the skin, often due to mis-trimming of the nail, or due to shoes that are too tight. An ingrown toenail can be painful and lead to infection.
Inguinal:  Having to do with the groin.
Inguinal canal:  A passage in the lower anterior abdominal wall which in the male allows passage of the spermatic cord and in the female contains the round ligament. Because of the weakness it creates in the abdominal wall, it is the most frequent site for a hernia.
Inguinal orchiectomy:  Surgery to remove the testicle, with the incision made through the groin.
Inhalant:  Any breathable chemical vapor.
Inherited metabolic diseases:   Also called inborn errors of metabolism, these are heritable (genetic) disorders of biochemistry. Examples include albinism, cystinuria (a cause of kidney stones), phenylketonuria (PKU), and some forms of gout, sun sensitivity, and thyroid disease. These are only a very few of the hundreds of known inborn errors of metabolism.
Inhibin:  One of two hormones (designated inhibin-A and inhibin-B) secreted by the gonads (by Sertoli cells in the male and the granulosa cells in the female) and that inhibit the production of follicle-stimulating hormone (FSH) by the pituitary gland. The inhibins also figure in the control of gametogenesis, and embryonic and fetal development. Inhibin-A is elevated in the blood serum of women carrying fetuses with Down syndrome. This discovery led to the inclusion of inhibin-A in the maternal serum screening tests for Down syndrome in the second trimester of pregnancy.
Iniencephaly:   A rare neural tube defect that combines extreme retroflexion (backward bending) of the head with severe defects of the spine. The affected infant tends to be short, with a disproportionately large head. The diagnosis can be made immediately after birth because the head is so severely retroflexed (bent back) that the face looks upward. The skin of the face is connected directly to the skin of the chest and the scalp is directly connected to the skin of the back. Generally, the neck is absent. The prognosis (outlook) for those with iniencephaly is extremely poor. Newborns with iniencephaly seldom live more than a few hours. The distortion of the fetal body may also pose a danger to the mother's life.
Injection snoreplasty:  An injection of a chemical called sodium tetradecyl sulfate that promotes stiffening of the soft palate by creating scar tissue in order to relieve snoring. The soft palate is the area above your throat in the back of your mouth. Snoring is typically caused by the fluttering of tissues of the back of the throat. The most common form of snoring is in fact called palatal flutter snoring.
Inkblot test:  A test used in clinical psychology and psychiatry involving inkblots. The inkblots are used to determine what a person perceives (reads into) in the enigmatic and highly ambiguous shapes. Ten standardized blots are shown one at a time to a subject and their responses are recorded. The test was created by Dr. Hermann Rorschach (1884-1922), a young Swiss psychiatrist. He published the test (also called the Rorschach test) in 1921, not long before his untimely death. The Rorschach test became a common psychological test and is still in use in psychology and psychiatry.
Innate immunity:  Immunity that is naturally present and is not due to prior sensitization to an antigen from, for example, an infection or vaccination. Since it is not stimulated by specific antigens, innate immunity is generally nonspecific. It is in contrast to acquired immunity. Also called natural immunity.
Inner ear:   There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The inner ear is far and away the most highly complex. The essential component of the inner ear for hearing is the membranous labyrinth where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end.
Innervate:  To supply with nerves. It is a little known fact that the cornea is the most densely innervated tissue in the body.
Inotropic:  Affecting the force of muscle contraction. An inotropic heart drug is one that affects the force with which the heart muscle contracts.
INR (International normalized ratio):   a system established by the World Health Organization (WHO) and the International Committee on Thrombosis and Hemostasis for reporting the results of blood coagulation (clotting) tests. All results are standardized using the international sensitivity index for the particular thromboplastin reagent and instrument combination utilized to perform the test. For example, a person taking the anticoagulant ("blood thinner") warfarin (brand name: Coumadin) might optimally maintain a prothrombin time (a "pro time" or PT) of 2 to 3 INR. No matter what laboratory checks the prothrombin time, the result should be the same even if different thromboplastins and instruments are used. This international standardization permits the patient on warfarin to travel and still obtain comparable test results.
Insecticide:   A chemical used specifically to kill or control the growth of insects. Certain insecticides have been banned because of their adverse effects on animals or humans. Dursban (chlorpyrifos) is one that has been banned. Dursban causes weakness, vomiting, diarrhea and other ill effects in children. Dursban was in hundreds of products including some of Raid sprays, Hartz yard and kennel flea spray, and Black Flag liquid roach and ant killer.
Insecticide-treated bednet (ITN):  A bednet that has been treated with insecticide to protect against mosquitos and malaria. "Provision of insecticide-treated bednets (ITNs) is universally accepted as an efficacious and essential public health service in most parts of sub-Saharan Africa endemic for malaria." (H Guyatt and S Ochola, Lancet 2003;362:1549).
Insemination:  The deposition of semen in the female reproductive tract. Under normal circumstances, the deposit is made within the vagina or the cervix (the opening to the uterus). By artificial means (such as intrauterine insemination), the deposit can be made directly into the uterus. The word "insemination" comes from "in," + "semen," seed.
Insomnia:  The perception or complaint of inadequate or poor-quality sleep because of one or more of the following: difficulty falling asleep; waking up frequently during the night with difficulty returning to sleep; waking up too early in the morning; or unrefreshing sleep. Insomnia is not defined by the number of hours of sleep a person gets or how long it takes to fall asleep. Individuals vary normally in their need for, and their satisfaction with, sleep. Insomnia may cause problems during the day, such as tiredness, a lack of energy, difficulty concentrating, and irritability.
Inspissate:  To thicken. Inspissated bile is thickened bile.
Insulin:  A natural hormone made by the pancreas that controls the level of the sugar glucose in the blood. Insulin permits cells to use glucose for energy. Cells cannot utilize glucose without insulin.
Insulin pump:  A pump for delivering insulin in order to achieve tight blood sugar control and lifestyle flexibility while minimizing the effects of low blood sugar (hypoglycemia).
Insulin resistance:  The diminished ability of cells to respond to the action of insulin in transporting glucose (sugar) from the bloodstream into muscle and other tissues. Insulin resistance typically develops with obesity and heralds the onset of type 2 diabetes. It is as if insulin is "knocking" on the door of muscle. The muscle hears the knock, opens up, and lets glucose in. But with insulin resistance, the muscle cannot hear the knocking of the insulin (the muscle is "resistant"). The pancreas makes more insulin, which increases insulin levels in the blood and causes a louder "knock." Eventually, the pancreas produces far more insulin than normal and the muscles continue to be resistant to the knock. As long as one can produce enough insulin to overcome this resistance, blood glucose levels remain normal. Once the pancreas is no longer able to keep up, blood glucose starts to rise, initially after meals, eventually even in the fasting state. Type 2 diabetes is now overt. In the meantime excessive insulin (hyperinsulinemia) produces a syundrome of its own which is termed "Syndrome X or the "Metabolic syndrome."
Insulinoma:  A tumor of the beta cells in areas of the pancreas called the islets of Langerhans. Although not usually cancerous, such tumors may cause the body to make extra insulin and may lead to hypoglycemia, a blood glucose (sugar) level that is too low.
Integrin:  One of a large and very important family of adhesion molecules that promote stable interactions between cells and their environment. The integrins also act as cellular sensor and signaling molecules.
Integron:  A mobile DNA element that can capture and carry genes, particularly those responsible for antibiotic resistance. Integrons do this by site-specific recombination.
Intelligence quotient (IQ):  An attempt to measure the intelligence of someone. The IQ score is usually based upon the results of a written test. To calculate the IQ, the person's mental age as determined by a test is divided by chronologic age, and the result is multiplied by 100.
Intelligence test:  A questionnaire or series of exercises designed to measure intelligence. It is generally understood that intelligence tests are less a measure of innate ability to learn as of what the person tested has already learned. There are many types of intelligence tests, and they may measure learning and/or ability in a wide variety of areas and skills. Scores may be presented as an IQ (intelligence quotient), a mental age, or on a scale.
Intelligence, non-verbal:  Innate or learned ability to understand and carry out motor tasks, such as solving physical puzzles. Also called Performance IQ.
Intelligence, verbal:  Innate or learned ability to understand and answer questions given in writing or verbally.
Intensity modulated radiation therapy (IMRT):  A type of three-dimensional radiation therapy that uses computer-generated images to match radiation to the size and shape of a tumor. In IMRT, thousands of tiny radiation beamlets enter the body from many angles and intersect the tumor. Since the intensity of each beamlet can be controlled, the radiation dose can wrap around normal tissue, create concave shapes and turn corners. The aim is to deliver a higher radiation dose to a tumor with less damage to nearby healthy tissue. IMRT may be used, for example, to treat a tumor that surrounds the spinal cord and spare the cord itself.
Intensive care unit psychosis:  A disorder in which patients in an intensive care unit (ICU) or a similar hospital setting may experience anxiety, become paranoid, hear voices, see things that are not there, become severely disoriented in time and place, become very agitated, even violent, etc. The condition has been formally defined as "acute brain syndrome involving impaired intellectual functioning which occurs in patients who are being treated within a critical care unit." ICU psychosis is a form of delirium, or acute brain failure. Organic factors including dehydration, hypoxia (low blood oxygen), heart failure (inadequate cardiac output), Infection and drugs can cause or contribute to delirium.
Intensivist:  A physician who specializes in the care of critically ill patients, usually in an intensive care unit (ICU).
Interatrial septum:  The partition separating the upper chambers (the atria) of the heart.
Intercellular:  Between cells, as opposed to intracellular (within cells).
Intercellular junction:  A specialized region of connection between two cells.
Intercostal muscle:  Muscle tissue between two ribs. This muscle is a type called skeletal muscle.
Intercurrent disease:   A disease that intervenes during the course of another disease. A patient with AIDS may develop an intercurrent bout of pneumonia.
Interferon:  A naturally occurring substance that interferes with the ability of viruses to reproduce. Interferon also boosts the immune system.
Interleukin-1:  A protein produced by various cells, including macrophages, interleukin-1 raises body temperature, spurs the production of interferon, and stimulates growth of disease-fighting cells, among other functions. Abbreviated IL-1.
Interleukin-10:  Abbreviated IL-10. An antiinflammatory and immunosuppressive substance produced within the body. IL-10 plays a role in the regulation of immune responses. It is secreted by antigen-presenting cells, promotes the development of immunologic tolerance, and suppresses the production of inflammatory cytokines. The gene for IL-10 is in chromosome region 1q31-q32. IL-10 modulates acute graft-versus-host disease (GVHD), a major complication in bone marrow transplant. The presence of a particular variant in the recipient's IL-10 gene is associated with a substantial decrease in the risk of GVHD. Knowledge of the recipient's IL-10 genotype helps predict the chance of GVHD.
Interleukin-2:  A type of interleukin, a chemical messenger, a substance that can improve the body's response to disease. It stimulates the growth of certain disease-fighting blood cells in the immune system. Also called IL-2.
Interleukin-3:  A protein that stimulates the immune system to develop mast cells and bone-marrow cells. Abbreviated IL-3.
Interleukin-4:  A protein that stimulates the immune system to develop mast cells, resting T-cells, and activated B-cells. Abbreviated IL-4.
Interleukins:  Substances used in biological therapy. Interleukins stimulate the growth and activities of certain kinds of white blood cells.
Intermediate-grade lymphoma:  A lymphoma that is more aggressive (grows and spreads faster) than a low-grade lymphoma, but responds better to anticancer drugs. Intermediate-grade lymphomas include diffuse, small, cleaved cell lymphoma and diffuse, large, noncleaved cell lymphoma. Also called an aggressive lymphoma.
Intermittent claudication:  An aching, crampy, tired, and sometimes burning pain in the legs that comes and goes -- it typically occurs with walking and goes away with rest -- due to poor circulation of blood in the arteries of the legs. In very severe claudication the pain is also felt ar rest. Intermittent claudication may occur in one or both legs and often continues to worsen over time. However, some people complain only of weakness in the legs when walking or a feeling of "tiredness" in the buttocks. Impotence is an occasional complaint in men. The usually intermittent nature of the pain is due to narrowing of the arteries that supply the leg with blood, limiting the supply of oxygen to the leg muscles, a limitation that is felt especially when the oxygen requirement of these muscles rises with exercise. Intermittent claudication can be due to temporary artery narrowing due to vasospasm (spasm of the artery), permanent artery narrowing due to atherosclerosis, or complete occlusion (closure) of an artery to the leg. The condition is quite common, more so in men than women. It affects 1-2% of the population under 60 years of age, 3-4% of persons age 60 to 70 and over 5% of people over 70.
Intermittent insomnia:   sleeplessness that occurs from time to time and each time lasts less than a week or two. Intermittent insomnia may not require treatment since the episodes of insomnia usually only last a few days at a time. For example, if insomnia is due to a temporary change in the sleep/wake schedule, as with jet lag, the biological clock will often get back to normal on its own.
Intern:  In medicine, a doctor who has completed medical school and is engaged in a year of additional training at a hospital before residency. An intern may, for example, be in pediatrics or medicine (internal medicine) or perhaps a "rotating" internship with 3-4 weeks in each specialty over one year. The internship year is often quite rigorous involving "all-nighters" every third night.
Internal bleeding:  Bleeding inside the body that is not seen from the outside. Internal bleeding occurs when damage to an artery or vein allows blood to escape the circulatory system and collect inside the body. The internal bleeding may occur within tissues, organs, or in cavities of the body including the head, chest, and abdomen.
Internal cardiac defibrillator:  A device put within the body that is designed to recognize certain types of abnormal heart rhythms (arrhythmias) and correct them.Defibrillators continuously monitor the heart rhythm in order to detect overly rapid arrhythmias that tend to develop in people with coronary artery disease and heart muscle diseases (cardiomyopathies). They are life- threatening. A defibrillator can be implanted within the body by far less invasive techniques than in the past because the devices, aside from being more technologically advanced, are smaller. (An implantable defibrillator is about the size of a minicassette). The defibrillator corrects the heart rhythm by delivering precisely calibrated and timed electrical shocks, when needed, to restore a normal heartbeat.
Internal carrier:  In the drug trade, an individual used to transport internally concealed illicit drugs. Also called a body packer.
Internal ear:  There are three sections of the ear. They are the external ear, the middle ear, and the internal ear. The internal ear is far and away the most highly complex. The essential component of the inner ear for hearing is the membranous labyrinth where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end. The membranous labyrinth is a system of communicating sacs and ducts (tubes) filled with fluid (the endolymph). The membranous labyrinth is lodged within a cavity called the bony labyrinth. At some points the membranous labyrinth is attached to the bony labyrinth and at other points the membranous labyrinth is suspended in a fluid (the perilymph) within the bony labyrinth.
Internal fixation:  A surgical procedure that stabilizes and joins the ends of fractured (broken) bones by mechanical devices such as metal plates, pins, rods, wires or screws. Internal fixation is as opposed to external fixation of a fracture by a splint or cast.
Internal jugular vein:  The deeper of the two jugular veins in the neck that drain blood from the head, brain, face and neck and convey it toward the heart. The internal jugular vein collects blood from the brain, the outside of the face and the neck. It runs down the inside of the neck outside the internal and common carotid arteries and unites with the subclavian vein to form the innominate vein.
Internal medicine:  A medical specialty dedicated to the diagnosis and medical treatment of adults. A physician who specializes in internal medicine is referred to as an internist. A minimum of seven years of medical school and postgraduate training are focused on learning the prevention, diagnosis, and treatment of diseases of adults. Subspecialties of internal medicine include allergy and immunology, cardiology (heart), endocrinology (hormone disorders), hematology (blood disorders), infectious diseases, gastroenterology (diseases of the gut), nephrology (kidney diseases), oncology (cancer), pulmonology (lung disorders), and rheumatology (arthritis and musculoskeletal disorders).
Internal pacemaker:  A device that uses electrical impulses to regulate the heart rhythm or to reproduce that rhythm. An internal pacemaker is one in which the electrodes into the heart, the electronic circuitry and the power supply are implanted (internally) within the body. Although there are different types of pacemakers, all are designed to treat bradycardia, a heart rate that is too slow). Pacemakers may function continuously and stimulate the heart at a fixed rate or at an increased rate during exercise. A pacemaker can also be programmed to detect too long a pause between heartbeats and then stimulate the heart.
Internal radiation therapy:  Radiation therapy in which radioactive material is placed in or near a tumor.
International normalized ratio (INR):  A system established by the World Health Organization (WHO) and the International Committee on Thrombosis and Hemostasis for reporting the results of blood coagulation (clotting) tests. All results are standardized using the international sensitivity index for the particular thromboplastin reagent and instrument combination utilized to perform the test. For example, a person taking the anticoagulant ("blood thinner") warfarin (brand name: Coumadin) might optimally maintain a prothrombin time (a "pro time" or PT) of 2 to 3 INR. No matter what laboratory checks the prothrombin time, the result should be the same even if different thromboplastins and instruments are used. This international standardization permits the patient on warfarin to travel and still obtain comparable test results.
International unit (IU):  An international unit (IU) is an internationally accepted amount of a substance. This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines). The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol. Nonetheless, most IUs are quite handy and helpful in use as a means of standardizing measures. All international units are officially defined by the International Conference for Unification of Formulae.
Interneuron:  A neuron that exclusively signals another neuron.
Internist:  A physician who specializes in the diagnosis and medical treatment of adults. This specialty, called internal medicine, is dedicated to adult medicine. A minimum of seven years of medical school and postgraduate training are focused on learning the prevention, diagnosis, and treatment of diseases of adults. Subspecialties of internal medicine include allergy and immunology, cardiology (heart), endocrinology (hormone disorders), hematology (blood disorders), infectious diseases, gastroenterology (diseases of the gut), nephrology (kidney diseases), oncology (cancer), pulmonology (lung disorders), and rheumatology (arthritis and musculoskeletal disorders).
Interpersonal therapy:  A form of psychotherapy in which the focus is on a patient's relationships with peers and family members and the way they see themselves. Interpersonal psychotherapy (IPT) is based on exploring issues in relationships with other people. The goal is to help people to identify and modify interpersonal problems, to understand and to manage relationship problems.
Intersex:  A group of conditions sometimes referred to as disorders of sexual development (DSDs) in which there is a discrepancy between the appearance of the external genitalia and the type of internal (testes and ovaries) genitalia. The condition was formerly termed hermaphroditism or pseudohermaphroditism. One example of intersex is the androgen insensitivity syndrome, in which the body's receptors to male hormones do not function properly. In this case, individuals have a male genetic makeup (XY) and testicular tissue but have incompletely formed or female external genitalia. In some cases, known as true gonadal intersex, a person has both ovarian and testicular tissue.
Intersexual genitalia:  Genitalia that are neither typically female nor typically male. Known in clinical medicine as ambiguous genitalia.
Interstice:  A small space between things, especially between things that are usually closely spaced, such as cells. Interstices are the cracks and crevices, the breaks, the gaps.
Interstitial:  Pertaining to being between things, especially between things that are normally closely spaced. The word "interstitial" is much used in medicine and has specific meaning depending on the context. For instance, interstitial cystitis is a specific type of inflammation of the bladder wall. Interstitial radiation involves placing radioactive material directly into a tumor. Interstitial pneumonia is inflammation of the lung which involves the meshwork of lung tissue (alveolar septa) rather than the air spaces (alveoli).
Interstitial cystitis (IC):  Disease that involves inflammation or irritation of the bladder wall. This inflammation can lead to scarring and stiffening of the bladder, and even ulcerations and bleeding. Diagnosis is based on symptoms, findings on cystoscopy and biopsy, and eliminating other treatable causes such as infection. Because doctors do not know what causes interstitial cystitis, treatments are aimed at relieving symptoms. Most people are helped for variable periods of time by one or a combination of treatments.
Interstitial radiation therapy:  Radiation treatment given by placing radioactive material directly into the target, often a tumor. For example, in treating prostate cancer, radioactive seeds are implanted in the prostate gland. The seeds might be titanium-encased pellets containing the radioisotope iodine-125. Interstitial radiation therapy is also called seed implantation or brachytherapy (brachys being Greek for short).
Intertrigo:  A superficial skin disorder involving any area of the body where opposing skin surfaces may touch and rub, such as the creases of the neck, the skin folds of the groin, axilla (armpit) and breasts (especially if large and pendulous) and between the toes. Intertrigo is characterized by skin reddening (erythema), softening and deterioration (maceration), burning, and itching. There may also be erosions, fissures (cracks) and exudation (oozing) and secondary infections. Factors that predispose to intertrigo include obesity, moisture, warmth, sweat retention and friction. Intertrigo comes from the Latin roots "inter-", between + -"terere", to rub.
Interval malignancy:  In mammography, a malignancy that becomes evident during the period between annual screening mammograms.
Interventional radiologist:  A radiologist who uses image guidance methods to gain access to vessels and organs. Interventional radiologists can treat certain conditions through the skin (percutaneously) that might otherwise require surgery. The technology includes the use of balloons, catheters, microcatheters, stents, and therapeutic embolization (deliberately clogging up a blood vessel). The specialty of interventional radiology overlaps with other fields, including interventional cardiology, vascular surgery, endoscopy, laparoscopy, and other minimally invasive techniques, such as biopsies. Specialists performing interventional radiology procedures today include not only radiologists but also other types of physicians such as general surgeons, vascular surgeons, cardiologists, gastroenterologists, gynecologists, and urologists.
Interventricular foramen:  An opening between the lateral and third ventricles in a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord.
Interventricular septum:  The stout wall separating the lower chambers (the ventricles) of the heart from one another. A hole in the interventricular septum is termed a ventricular septal defect (VSD).
Intervertebral disk:  A pad of cartilage between two vertebrae that acts as a shock absorber.
Intervertebral foramen:  An opening between vertebrae through which nerves enter and leave the spinal courd and extend to other parts of the body. Also called a neural foramen.
Intestinal obstruction:  Blockage of the intestine by infolding (intussusception), malformation, tumor, digestive problems, a foreign body, or inflammation. Symptoms can include crampy abdominal pain, lack of ability to eliminate normal feces, and eventually shock. On examining the abdomen, the doctor may feel a mass. Abdominal X-rays may suggest intestinal obstruction, but a barium enema may be needed to show the actual cause.
Intestinal parasite:  A parasite (any organism that lives in or on and takes its nourishment from another organism) in the intestinal tract. Intestinal parasites include both helminths and protozoa. Helminths are worms such as tapeworms, pinworms, and roundworms. All of these worms can live, but typically not reproduce, inside the human intestine. In contrast to worms, which are composed of many cells, protozoa are single-celled organisms that can multiply inside the body. Examples of protozoa that can live in the intestinal tract are Giardia and Cryptosporidium.
Intestinal pseudo-obstruction:  Symptoms of intestinal obstruction with no sign of actual physical obstruction. This condition may be due to problems with the nerves that control intestinal muscles or other causes.
Intestinal villi:  Microscopic projections from the surface of the small intestine which vastly increases the absorptive surface area and thus helps absorb nutrients and fluids.
Intestine:  The long, tubelike organ in the abdomen that completes the process of digestion. It consists of the small and large intestines.
Intra-arterial pressure:  The pressure of the blood within the arterial system, aka arterial pressure and arterial tension.
Intracellular:  Within a cell. In contrast to extracellular, meaning outside a cell, and intracellular, meaning between cells.
Intracerebral hematoma:  A blood clot within the brain, the result of bleeding within the brain.
Intracranial:  Within the cranium, the bony dome that houses and protects the brain.
Intracranial hematoma:  A collection of blood within the skull. The bleed may or may not be within the brain itself. If it is within the brain, it is known as "intracerebral."
Intractable:  Unstoppable. For example, intractable diarrhea or intractable pain.
Intracytoplasmic sperm injection (ICSI):  A test-tube fertilization procedure in which a sperm is injected directly into an egg to achieve fertilization. ICSI is done for male infertility. (Babies conceived by ICSI have no more major birth defects or delays in development than children conceived by natural means.)
Intradermal:  In or into the skin. An intradermal injection is given into the skin.
Intradiskal electrothermal therapy (IDET):  A procedure designed to relieve back pain due to damage to the disks between the spine bones. Called IDET for short. Under local anesthesia and X-ray guidance, a needle is introduced into the disk and a catheter with a heating coil is inserted through the needle. The tip of the catheter is then gradually heated to seal the breach in the collagen in the disk wall. The aim is to kill the tiny nerve endings that carry pain signals from the site and so relieve the pain. Following the procedure, the patient should be able to leave the hospital within two hours. The value of this procedure is still unproven. I had the procedure in 1998 and found it worthless.
Intraductal carcinoma:  A form of breast cancer, also called ductal carcinoma in situ, DCIS.
Intraductal papilloma:  A benign, wart-like growth that occurs in breast ducts.
Intraepithelial:  Within the layer of cells that forms the surface or lining of an organ.
Intrafallopian:  A term meaning "within the fallopian tube," also called oviducts which serve as passageways connecting the egg-producing ovaries to the uterus in the pelvis.
Intrahepatic:  Within the liver.
Intramuscular (IM):  An intramuscular (IM) medication is given by needle into the muscle. This is as opposed to a medication that is given by a needle, for example, into the skin (intradermal) or just below the skin (subcutaneous) or into a vein (intravenous).
Intraocular:  In the eye.
Intraocular lens (IOL):  An artificial lens made of plastic, silicone, acrylic or other material that is implanted inside the eye during cataract surgery.
Intraocular melanoma:  An eye cancer in which the malignant cells arise in the part of the eye called the uvea. The uvea includes the iris (the colored part of the eye), the ciliary body (a muscle in the eye), and the choroid (a layer of tissue in the back of the eye). The uvea contains pigment-producing cells called melanocytes. When these cells become cancerous, the cancer is called a melanoma. Intraocular melanoma occurs most often in people who are middle aged.
Intraocular pressure:  The pressure created by the continual renewal of fluids within the eye. The intraocular pressure is increased in glaucoma.
Intraoperative:  During surgery. Literally, within surgery. Intraoperative hemorrhage is bleeding during surgery.
Intraoperative blood salvage:  The recovery of blood that has been lost into a body cavity during surgery or due to trauma. This blood can then be reintroduced into the patient's circulation, reducing the need for donor blood transfusion.
Intraoperative radiation therapy (IORT):  Radiation treatment given during surgery.
Intraoral:  Within the mouth.
Intraperitoneal:  Within the peritoneal cavity, the space that contains the abdominal organs.
Intraperitoneal chemotherapy:  Treatment in which anticancer drugs are put directly into the abdomen through a thin tube.
Intrastromal corneal ring:  A plastic ring designed to be implanted in the cornea, the transparent structure in the front of the eye. The aim of the corneal ring implant is to flatten the cornea and in so doing to correct or reduce the degree of myopia (nearsightedness). The ring is called an intrastromal ring because it is placed in the corneal stroma, the middle one of the five layers that make up the cornea.
Intrathecal chemotherapy:  Treatment with drugs that are injected into the fluid surrounding the brain and spinal cord (cerebrospinal fluid).
Intrauterine:  In the uterus (the womb). As opposed to extrauterine: outside the uterus.
Intrauterine contraceptive device (IUD):  A device inserted into the uterus (womb) to prevent conception (pregnancy). The IUD can be a coil, loop, triangle, or T-shape. It can be plastic or metal. An IUD is inserted into the uterus by a health-care professional. Of two types of IUDs approved in the U.S., one can remain in place for 10 years, while the other must be replaced every year.
Intrauterine growth restriction:  The growth of the fetus is abnormally slow. When born, the baby appears too small, considering its' dates. Intrauterine growth restriction is associated with increased risk of medical illness and death in the newborn. Intrauterine growth restriction is also referred to as intrauterine growth retardation.
Intrauterine insemination (IUI):  A procedure in which a fine catheter (tube) is inserted through the cervix (the natural opening of the uterus) into the uterus (the womb) to deposit a sperm sample directly into the uterus. The purpose of IUI is to achieve fertilization and pregnancy. IUI is a relatively simple procedure.
Intravenous (IV):  (1) Into a vein. administered directly into the venous circulation via a syringe or intravenous catheter or needle. (2) The actual solution that is administered intravenously. (3) The device used to administer an intravenous solution, such as the familiar IV drip used to slowly drip a bag or bottle of electrolyte solution into a dehydrated patient through a tiny plastic tube or needle inserted directly into a vein.
Intravenous cholangiogram (IVC):  A radiologic procedure used primarily to look at the larger bile ducts in the liver and the bile ducts outside the liver. IVC can be used to locate gallstones within the bile ducts and identify other causes of obstruction to the flow of bile. For an IVC, an iodine-containing dye is injected intravenously. The dye is removed from blood by the liver which excretes it into the bile. The dye outlines the bile ducts and any gallstones that may be within them.
Intravenous feeding:  Feeding through a vein. Also called parenteral alimentation or parenteral nutrition.
Intravenous immunoglobulin (IVIG):  A sterile solution of concentrated antibodies extracted from healthy people that is given straight into a vein. It is used to treat disorders of the immune system, or to boost immune response to serious illness. Also abbreviated IGG (for intravenous gamma globulin).
Intravenous pyelogram (IVP):  An x-ray of the kidneys and urinary tract. Structures are made visible by the injection of a substance that blocks x-rays.
Intravenous tension:  The pressure of the blood within a vein, the venous pressure, normally 15 mm mercury, i.e. adequate pressure to elevate a column of mercury 15 millimeters.
Intraventricular:  In the ventricle of the heart or brain.
Intravitreous:  In the vitreous, the fluid behind the lens in the eye. As in an intravitreous injection.
Intrinsic:  1. An essential or inherent part of a something such as a structure. 2. Coming from within, from the inside. From the Latin intrinsecus meaning situated on the inside. The opposite of intrinsic is extrinsic.
Introitus:  In anatomy, an introitus is an entrance, one that goes into a canal or hollow organ. For example, the introitus of the facial canal is the entrance to the facial canal, a passage in the temporal bone of the skull through which the facial nerve (the 7th cranial nerve) travels. The most common usage involves the introitus of the vagina (the opening to the vagina). When the singular word "introitus" is used in medicine, this is to what it refers.
Intron:  Part of a gene that is initially transcribed into the primary RNA transcript but then removed from it when the exon sequences on either side of it are spliced together. Also called an intervening sequence.
Intubate:  To put a tube into a hollow organ or passageway, often into the airway. The opposite of intubate is extubate.
Intussusception:  Telescoping (prolapse) of a portion of the intestine within another immediately adjacent portion of intestine. This decreases the supply of blood to the affected part of the intestine, and frequently leads to intestinal obstruction. The pressure created by the two walls of the intestine pressing together causes inflammation, swelling, and reduces the blood flow. Death of bowel tissue can occur, with significant bleeding, perforation, abdominal infection, and shock occurring very rapidly. Intussusception is a medical emergency.
Invasive candidiasis:  A fungal infection that occurs when Candida (a yeast-like fungus) enters the bloodstream and then spreads through the body. Candida is the fourth most common cause of bloodstream infection among hospitalized patients in the US. A survey found that candidemia (bloodstream infection with Candida) occurs in 8 of every 100,000 persons per year. Persons at high risk for candidemia include low-birth-weight babies, surgical patients, and those whose immune systems are deficient.
Invasive cervical cancer:  Cancer that has spread from the surface of the cervix to tissue deeper in the cervix or to other parts of the body.
Inverse psoriasis:  Also called flexural psoriasis, a form of psoriasis found in the armpits, groin, under the breasts and in other flexion creases (skin folds) such as those around the genitals and buttocks. This form of psoriasis appears as smooth, dry areas of skin that are red and inflamed but do not have the scaling associated with plaque psoriasis (the most common type of psoriasis). Inverse psoriasis is more frequent and severe in people who are overweight because it is in the skin folds where it is particularly prone to irritation from rubbing and sweating.
Invert:  1) To turn inward. To invert the foot is to move its forepart toward the midline of the body. 2) To turn upside down or inside out. Inversion of the nipple can be normal or be a sign of an underlying tumor. 3) To reverse in position or order. A DNA sequence may be inverted.
Invest:  In medicine, this has nothing to do with the stock market. It means to envelop, cover, or embed.
Involuntary:  Done other than in accordance with the conscious will of the individual. The opposite of voluntary. The terms "voluntary" and "involuntary" apply to the human nervous system and its control over muscles. The nervous system is divided into two parts -- somatic and autonomic. The somatic nervous system operates muscles that are under voluntary control. The autonomic (automatic or visceral) nervous system regulates individual organ function and is involuntary. Opening the mouth is voluntary while blushing is involuntary.
Involuntary smoking:  The involuntary inhaling of environmental tobacco smoke ("secondhand smoke") by someone who is not smoking.
Involute:  1. Literally, to turn inward or roll inward. 2. To decrease in size after an enlargement. The uterus involutes after pregnancy. The thymus involutes after adolescence. 3. To undergo a retrograde change. After treatment, a tumor may involute. 4. To shrink physically and emotionally with advancing age (senile involution).
Iodide:  The chemical form to which iodine in the diet is reduced before it is absorbed through the intestinal wall into the bloodstream and carried through the blood to the thyroid gland.
Iodine:  An essential element in the diet used by the thyroid gland to make thyroid hormones. Iodine is found in seafood, bread, salt, and seaweed.
Iodine deficiency:  Iodine is a natural requirement of our diets. Iodine deficiency can lead to inadequate production of thyroid hormone from the thyroid gland (hypothyroidism). For example, in some parts of Zaire, Ecuador, India, and Chile, remote, mountainous areas, such as in the Alps (in the past), Andes and the Himalayas have a particular predisposition to severe iodine deficiency, goiter, and hypothyroidism. Since the addition of iodine to table salt, iodine deficiency is rarely seen in the United States. Before that, until the early part of the 20th century this kind of hypothyroidism was endemic around the Great Lakes.
Iodine excess:  Just as too little iodine can cause thyroid disease, so may prolonged intake of too much iodine also lead to the development of goiter (swelling of the thyroid gland) and hypothyroidism (abnormally low thyroid activity). Certain foods and medications contain large amounts of iodine. Examples include seaweed; iodine-rich expectorants (such as SSKI and Lugol's solution) used in the treatment of cough, asthma, chronic pulmonary disease; and amiodarone (CARDORONE), an iodine-rich medication used in the control of abnormal heart rhythms (cardiac arrhythmias).
Iodine, radioactive:  An isotope of the chemical element iodine that is radioactive. Radioactive iodine is used in diagnostic tests as well as in radiotherapy of an hyperactive thyroid gland (hyperthyroidism), most often due to Graves disease. For hyperthyroidism, Radioactive iodine is administered in capsule form on a one- time basis. It directly radiates thyroid tissues, thereby destroying them. It takes 8-12 weeks for the thyroid to become euthyroid (normal) after treatment. The majority of patients undergoing this treatment with radioactive iodine eventually become hypothyroid, which is easily treated using thyroid hormones.
Ion channel:  A protein that acts as a pore in a cell membrane and permits the selective passage of ions (such as potassium ions, sodium ions, and calcium ions), by means of which electrical current passes in and out of the cell. Ion channels also serve many other critically important functions including chemical signalling, transcellular transport, regulation of pH, and regulation of cell volume. Malfunction of ion channels can cause diseases in many tissues. The array of human diseases associated with defects in ion channels is growing. These diseases are called channelopathies.
Iontophoresis:  A transdermal delivery system in which a substance bearing a charge is propelled through the skin by a low electrical current. This method can be used to drive a drug across the skin barrier, as is done with pilocarpine to stimulate sweating in the sweat chloride test for cystic fibrosis. Iontophoresis can also be used in the reverse direction to draw a molecule such as glucose through the skin.
IOP (intraocular pressure):  The pressure created by the continual renewal of fluids within the eye. The normal IOP varies among individuals. The intraocular pressure is increased in glaucoma.
Ipecac:  A naturally occurring substance with multiple properties including the ability to cause vomiting (emesis). Ipecac is derived from dried roots of a bush called Uragoga ipecacuanha native to Brazil. In the past, a sizable proportion of poison exposures in the U.S. were treated with ipecac. This practice has dropped off and some experts recommend that it should be abandoned, except in rare instances. Emesis only occurs about 30 minutes after thte administration of ipecac and is very sudden and unexpected (to come in that exact moment).
Ipsilateral:  On the same side.
IPT (interpersonal therapy):  A form of psychotherapy in which the focus is on a patient's relationships with peers and family members and the way they see themselves.
IPV (Inactivated polio vaccine):  The polio virus in IPV has been inactivated (killed). The inactivated polio vaccine (IPV) is also called the Salk vaccine after the late American physician-virologist Jonas Salk. The vaccines available for vaccination against polio are the IPV (inactivated polio vaccine) and the OPV (oral polio vaccine). IPV (inactivated polio vaccine) is given as a shot in the arm or leg. OPV (oral polio vaccine) is the preferred vaccine for most children. As polio is no longer epedemis, many parents elect not to give vaccines to their children and this causes great consternation among public health officials.
IQ (intelligence quotient):  an attempt to measure the intelligence of someone. The IQ score is usually based upon the results of a written test. To calculate the IQ, the person's mental age (as determined by a test) is divided by their chronologic age and the result is multiplied by 100.
Iressa:  Brand name for gefitinib, a drug that attaches to the epidermal growth factor receptor (EGFR) on the surfaces of cells . People with non-small-cell lung cancer who have a mutation in the gene for EGFR enjoy a rapid and often dramatic response to the drug.
Iridectomy:  The process of making a hole in the iris by surgically removing a full-thickness piece from the iris.
Iridology:  The practice of diagnosing disease by examining the iris of the eye. Although some diseases do affect the eye, iridology is not considered scientific medicine.
Iris:  The iris is the circular, colored curtain of the eye. Its opening forms the pupil. The iris helps regulate the amount of light that enters the eye.
Iris, speckled:  Due to little white (or lightly colored) spots that are slightly elevated on the surface of the iris. These spots, arranged in a ring concentric with the pupil, occur in normal children but are far more frequent in Down's syndrome (trisomy 21). They were described in 1924 by Thomas Brushfield, are called Brushfield's spots, and are due to aggregation of a normal iris element (connective tissue).
Iritis:  Inflammation of the iris. The iris is the circular, colored curtain in the front of the visible of the eye. (The opening of the iris forms the pupil.)
Iron:  An essential mineral. Iron is necessary for the transport of oxygen (via hemoglobin in red blood cells) and for oxidation by cells (via cytochrome). Deficiency of iron is a common cause of anemia. Food sources of iron include meat, poultry, eggs, vegetables and cereals (especially those fortified with iron). According to the National Academy of Sciences, the Recommended Dietary Allowances of iron are 15 milligrams per day for women and 10 milligrams per day for men. Iron overload can damage the heart, liver, gonads and other organs. Iron overload is a particular risk in people who may have certain genetic conditions (hemochromatosis) sometimes without knowing it and also in people receiving recurrent blood transfusions. Iron supplements meant for adults (such as pregnant women) are a major cause of poisoning in children.
Iron deficiency anemia:  The most common known form of nutritional disorder in the world, iron deficiency results in anemia because iron is necessary to make hemoglobin, key molecule in red blood cells responsible for the transport of oxygen. In iron deficiency anemia, the red cells appear abnormal and are unusually small (microcytic) and pale (hypochromic). The pallor of the red cells reflects their low hemoglobin content.
Iron excess:  Iron overload can damage the heart, liver, gonads and other organs. Iron overload is a particular risk for: •People with certain genetic conditions such as hemochromatosis; and •People receiving repeated blood transfusions. According to the National Academy of Sciences, the Recommended Dietary Allowances of iron are 15 milligrams per day for women and 10 milligrams per day for men.
Iron poisoning:  Iron supplements meant for adults (such as pregnant women) are a major cause of poisoning in children. Care should be taken to keep iron supplements safely away from children.
Irradiation:  Radiation from x-rays, gamma rays, neutrons, and other sources (in medicine can be used to kill cancer cells and shrink tumors). Radiation may come from a machine outside the body (external-beam radiation therapy) or from materials called radioisotopes.
Irrigate:  To wash out as, for example, a wound - to clean it. In surgery irrigation is considered even more important than scrubbing as a disinfecting procedure although both methods are used sequentially.
Irritable bowel syndrome (IBS):  A common gastrointestinal disorder involving an abnormal condition of gut contractions (motility) characterized by abdominal pain, bloating, mucous in stools, and irregular bowel habits with alternating diarrhea and constipation, symptoms that tend to be chronic and to wax and wane over the years. Although IBS can cause chronic recurrent discomfort, it does not lead to any serious organ problems. Also called spastic colitis, mucus colitis, nervous colon syndrome.
Irritant contact dermatitis:  A rash brought about by constant irritation from a substance. For example, anyone who washes their hands many times a day can develop "dish pan hands." Another example is in young children who lick their lips repeatedly, resulting in an irritant reaction to saliva.
Ischemia:   Inadequate blood supply (circulation) to a local area due to blockage of the blood vessels to the area.
Ischial bursitis:  Inflammation of the bursa that separates the gluteus maximus muscle of the buttocks from the underlying bony prominence of the bone that we sit on, the ischial tuberosity. Ischial bursitis is a form of bursitis that is usually caused by prolonged sitting on hard surfaces that press against the bones of the bottom or mid-buttocks. Ischial bursitis is also referred to as weaver's bottom because weavers traditionally would weave in a position that aggravated the affected bursa.
Ischium:  Bone making up the lower down back part of the pelvis.
Islet cell cancer:   A rare but highly treatable type of pancreatic cancer that begins in the cells of the pancreas that produce insulin and other hormones. Islet cell cancer can cause the pancreas to produce too much insulin or other hormones. When this happens, the patient may feel weak or dizzy and may have chills, muscle spasms, and diarrhea as well as pain in the stomach or abdomen. Islet cell cancer is also called islet cell carcinoma and islet cell tumor.
Islets of Langerhans:  Known as the insulin-producing tissue, the islets of Langerhans do more than that. They are groups of specialized cells in the pancreas that make and secrete hormones discovered in 1869, these cells sit in groups that Langerhans likened to little islands in the pancreas. There are five types of cells in an islet: alpha cells that make glucagon, which raises the level of glucose (sugar) in the blood; beta cells that make insulin; delta cells that make somatostatin which inhibits the release of numerous other hormones in the body; and PP cells and D1 cells, about which little is known. Degeneration of the insulin-producing beta cells is the main cause of type I (insulin-dependent) diabetes mellitus.
Iso-:  Equal, like, or similar. Iso- is much used in medicine and science as, for example, in isotonic solution (a solution that has the same salt concentration as cells and blood), isotope (a form of a chemical element with the same atomic number as another element but having a different atomic mass). The opposite of iso- is aniso-. Iso- is derived from the Greek "isos" meaning "equal or like."
Isochromosome:  An abnormal chromosome with two identical arms due to duplication of one arm and loss of the other arm. Isochromosomes are found in some girls with Turner syndrome, patients with the Pallister-Killian syndrome, and some tumors.
Isodisomy:  Remarkable situation where both chromosomes in a pair are from one parent and neither from the other. Isodisomy causes some birth defects and, we suspect, plays a role in cancer. Also called uniparental disomy.
Isoflavone:  A type of plant estrogen (phytoestrogen) found chiefly in soybeans.
Isoform:  A protein that has the same function as another protein but which is encoded by a different gene and may have small differences in its sequence.
Isolate:  A group in which mating is always between members of the group. For example, the Amish.
Isoleucine:  An amino acid, one of the 20 building blocks of protein. A dietary essential amino acid, isoleucine is needed for optimal growth in childhood.
Isometric exercise:  Exercise involving muscular contractions without movement of the involved parts of the body. Isometric exercise is one method of muscular exercise. In contrast, isotonic exercise occurs when a contracting muscle shortens against a constant load, as when lifting a weight.
Isometropia:  The condition in which both eyes have equal refractive power. If, for example, one eye is myopic (nearsighted), so is the other. Or if one eye is hyperopic (farsighted), so is the other. Or both eyes may have normal refractive power.
Isoprene:  One of the major components that makes up natural rubber and is used to make synthetic rubbers. It is also emitted from plants and trees, has been detected in tobacco smoke and automobile exhaust. Isoprene is a possible carcinogen (cancer-causing agent).
Isotonic solution:  A solution that has the same salt concentration as the normal cells of the body and the blood. As opposed to a hypertonic solution or a hypotonic solution. An isotonic beverage may be drunk to replace the fluid and minerals which the body uses during physical activity.
Isotonic, exercise:  Exercise when a contracting muscle shortens against a constant load, as when lifting a weight. Isotonic exercise is one method of muscular exercise. In contrast, isometric exercise is when muscular contractions occur without movement of the involved parts of the body.
Isotope:  A form of a chemical element with the same atomic number as another element but having a different atomic mass. For example deuterium (heavy hydrogen) is an isotope of hydrogen. They both have one electron and one proton, but deuterium also has a neutron as well as a proton giving it an atomic weight of 2 in contrast to hydrogen with an atomic weight of 1. (Water made with deuterium is termed "heavy water"). Isotopes are used in a number of medical tests.
Italian disease:  Syphilis. Depending upon someone's thoughts as to where the disease came from, syphilis was also known as the French, Spanish, German and Polish disease.
IU (international unit):  An international unit (IU) is an internationally accepted amount of a substance. This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines). The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol. Nonetheless, most IUs are quite handy and helpful in use as a means of standardizing measures.
IUD (intrauterine contraceptive device):  A device inserted into the uterus (womb) to prevent conception (pregnancy). The IUD can be a coil, loop, triangle, or T-shape. It can be plastic or metal. An IUD is inserted into the uterus by a health-care professional. Of two types of IUDs approved in the U.S., one can remain in place for 10 years, while the other must be replaced every year. How IUDs prevent pregnancy is not entirely clear. They seem to prevent sperm and eggs from meeting by either immobilizing the sperm on their way to the fallopian tubes or by changing the uterine lining so the fertilized egg cannot implant in it. UDs have one of the lowest failure rates of any contraceptive method. " In the population for which the IUD is appropriate -- for those in a mutually monogamous, stable relationship who are not at a high risk of infection -- the IUD is considered a safe and effective method of contraception.
IV (intravenous):  Within a vein. IV is the abbreviation for "intravenous." The word "intravenous" is quite properly an adjective meaning, according to Merriam Webster's Collegiate Dictionary, "situated, performed, or occurring within or entering by way of a vein." In recent years, the word "intravenous" has taken on a second role: as a noun. Thus, "an intravenous" refers to an intravenous fluid drip, a solution (usually a balanced electrolyte solution) administered directly into the venous circulation. Also called a drip.
IVF (In vitro fertilization):  a laboratory procedure in which sperm are placed with an unfertilized egg in a Petri dish to achieve fertilization. The embryo is then transferred into the uterus to begin a pregnancy or cryopreserved (frozen) for future use.



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