Adrenal Glands

Adrenal Glands

Dr. KennedyThe adrenal glands are a pair of small glands, each of which sits on top of one of the kidneys. The adrenal is made up of an outer wall (the cortex) and an inner portion (the medulla). The adrenal glands produce hormones that help control the heart rate, blood pressure, the way the body uses food, and other vital functions. The adrenal cortex secretes steroid (cortisone-related) hormones and mineralocorticoids that regulate the levels of minerals such as sodium and potassium in the blood. The adrenal medulla makes adrenaline (epinephrine) noradrenaline (norepinephrine). Adrenaline is secreted in response to low blood levels of glucose as well as exercise and stress; it causes the breakdown of the storage product glycogen to the sugar glucose in the liver, facilitates the release of fatty acids from adipose (fat) tissue, causes dilation (widening) of the small arteries within muscle and increases the output of the heart. Noradrenaline is a neurotransmitter for the sympathetic nervous system. In addition adrenaline is a sympathomimetic catecholamine, i.e. it causes quickening of the heart beat, strengthens the force of the heart contraction, opens up the bronchioles in the lungs and has numerous other effects. The secretion of adrenaline by the adrenal is part of the “fight-or-flight” reaction that we have in response to being upset or frightened.

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