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Chapter

Chapter notes - the adrenal glands


Department
Biology
Course Code
BIO220H1
Professor
Matthews

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The Adrenal Glands
primary endocrine gland located above the kidneys; divided into an outer cortex (80% of
glands total mass) and an inner medulla
Adrenal Cortex - outer portion of the adrenal gland; secretes adrenocorticosteroids
Zona glomerulosa – outer later
Zona fasciculate middle layer
Zona reticularisinner layer
Adrenocorticoids - steroid hormones secreted from the adrenal cortex
Includes 3 types :
1. Mineralocorticoids - regulate sodium reabsorption and potassium secretion by the
kidneys (aldosterone) secreted by zona glomerulosa
2. Glucocorticoids - regulate the bodys response to stress, regulate protein, carbohydrate,
and lipid metabolism in a variety of tissues, and regulate blood glucose levels (Cortisol)
– zona fasciculata and reticularis
3. Sex Hormones - including estrogens, progesterone, and androgens secreted from the
adrenal cortex and gonads that regulate reproductive function, promote gametogenesis,
growth and maintenance of reproductive organs, and the development of secondary sex
characteristics (androgens) – zona reticularis and fasciculata
Adrenal medulla - inner portion of the adrenal gland; secretes catecholamines . 80 % =
epinephrine (adrenaline); 20% = nor epinephrine; 1% = Dopamine
Secretion of Glucocorticoids
Adrenocorticotropic hormone (ACTH) - tropic hormone secreted from the anterior pituitary
that stimulates secretion of glucocorticoids from the adrenal cortex
Corticotropin releasing hormone (CRH) - tropic hormone released by the hypothalamus that
stimulates secretion of ACTH from the anterior pituitary
Glucocorticoid are steroids, Lipophilic and diffuse immediately in adrenal cortex to
bloodstream after synthesis.
Plasma glucocorticoids levels are reg. by negative feedback on hypothalamus and ant.pit.
w/c limits CRH and ACTH sec.
Cortisolglucocorticoids released fr. Adrenal cortex; ties up with circadian rhythm
sleep- wake cycle.
Stress – stimulus for cortisol sec.
Aldosterone Actions
The effects of Aldosterone (Fig.19.14)
Aldosterone - a steroid hormone released from the adrenal cortex that regulates the reabsorption
of sodium and secretion of potassium. Role in Na+ reabsorption.
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