Term
| What are the three layers of the adrenal cortex and what does each produce? |
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Definition
1. Zona glomerulosa - Aldosterone (mineralcorticoid)
2. Zona fasciculata - Cortisol (glucocorticoid)
3. Zona reticularis - cortisol |
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Term
| What type of cells are found in the adrenal medulla, and what do they produce? |
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Definition
| Chromaffin cells are in the adrenal medulla, and they produce epinephrine and norepinephrine |
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Term
| What are glucocorticoids and what do they do? |
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Definition
| 1. Glucocorticoids - Cortisol increases glucose concentration in plasma by stimulating hepatic gluconeogenesis. Cortisol mmodulates the functioniing of glucose-regulated tissues (liver, fat, and muscle) as well as most tissues in the body, including the CNS |
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Term
| What are mineralocorticoids and what do they do? |
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Definition
| Aldosterone regulates Na and K and water retention in the kidneys |
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Term
| What are sex steroids and what do they do? |
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Definition
| Androgens from the cortex are important for the development of secondary sex characteristics |
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Term
| What are the steps involved in glucocorticoid synthesis? |
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Definition
1. C27 cholesterol is converted to C21 Pregnenolone
2. Pregnenolone is converted to progesterone.
3. blah blah blah |
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Term
| What is the rate limiting step in glucocorticoid synthesis? |
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Definition
| Conversion of C27 cholesterol to C21 pregnenelone |
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Term
| What does cortisol do? Liver, muscle, adipose tissue, kidney, connective tissue, trabecular bone, GI tract? |
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Definition
Plays a role in teh conversion of protein into glycogen, supporting catabolic metabolism.
Liver - increaes glycogenesis
Muscle - increases muscle catabolism for the breakdown of protein to amino acids
Adipose tissue - enhances the conversion of fat to fatty acids
Kidney - increases GFR and is essential for excretion of water load
Connective tissue - inhibits collagen synthesis, resulting in thinning of the skin
Trabecular bone - increases bone resorption. Also causes a decrease in the synthesis of new bone
GI tract - absorption of calcium is diminished by cortisol
Immune system - causes increased release of neutrophils into the circulatory system |
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Term
| What happens to the kidney in the absence of cortisol? |
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Definition
| More ADH is synthesized, enhancing the effecdt of ADH on the renal tubules. Cortisol increases Ca+2 and phosphate excretion by decreasing reabsorption in the proximal tubule. |
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Term
| How is glucocorticoid synthesis and secretin regulated? |
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Definition
By the hypothalamic-pituitary-adrenocortical axis
CRH is synthesized by the hypothalamus and is released at the median emminence, carried through the long portal vein to the ant. pituitary.
Once bound to CRH, adenylyl cyclase activates to produce cAMP. Results in increased Ca+2 which elicits release of ACTH.
ACTH binds to the melanocortin 2 receptor on the surface of the adrenal cortex. ACTH only binds to cells in the zonula fasciculata and reticularis.
Once bound to ACTH, these cells produce cortisol |
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Term
| What is the common precursor between mineralocorticoids and glucocorticoids? |
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Definition
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Term
| What is the action of aldosterone on the kidney? |
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Definition
| It increases the expression of the Na, K pump, Na channels and the Na, K, Cl cotransporter. These cause increased Na reabsorption and increased K secretion |
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Term
| What are the three mediators of aldosterone production? |
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Definition
1. angiotensin II
2. increased concentration of extracellular K
3. ACTH |
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Term
| What is the cellular action of angiotensin II? |
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Definition
It stimulates aldosterone synthesis as well as vasoconstrict. Angiotensin II binds to the AT receptor on glomerulosa cells. This receptor activates PLC, resulting in DAG, IP3, and increased Ca+2. Ca influx causes synthesis of aldosterone through the increasing availability of pregnenolone.
Ang II and aldosterone both feedback inhibit renin release |
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Term
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Definition
complete destruction of the adrenal cortex
low Na, hi K, low BP; muscle weakness, vomiting, dehydration, anorexia, hypoglycemia, hyperpigmentation |
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Term
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Definition
Chronic glucocorticoid excess.
Excess ACTH
Adrenal hyperplasia
Thin arms, legs due to protein catabolism. Fat in the extremities, face, across the shoulder blades and the base of neck.
Hypertension, hyperglycemia - can lead to diabetes |
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Term
| How are chromaffin cells stimulated? |
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Definition
Release of acetylcholine by the preganglionic neurons of the splanchnic nerves causes depolarization of chromaffin cell plasma membrane.
Activation of Ca+2 channels increases the intracellular Ca concentration and stimulates the exocytosis of the chromaffin granules |
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Term
| How is catecholamine degradation mediated? |
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Definition
| By catecholamine O methyltransferase and monoamine oxidase |
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Term
| How are catecholamines synthesized? |
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Definition
| Tyrosine -> Dopa -> Dopamine -> Norepinephrine -> Epinephrine |
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