The Adrenal glands, each weighing about four grams, sit at the top of the kidneys a bit like lopsided pyramids. They consist of an outer layer, called the cortex, around a middle layer called the medulla. The cortex is responsible for the production of a number of different hormones: aldosterone, produced by the action of renin from the kidney and responsible for the maintenance of our salt balance, cortisol which is produced in response to stress under the influence of a hormone from the pituitary called ACTH (adreno-cortico trophic hormone) and which has effects on glucose, protein and fat metabolism, and small amounts of sex hormones which have similar effects to testosterone. The medulla, in the middle, manufactures adrenalin and noradrenaline which are secreted into the bloodstream when the gland is stimulated by nerves of the sympathetic nervous system.
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