Lecture 18 - Adrenal Glands I Flashcards
Jan 28, 2019 - Murray
From superficial to deep, what are the layers of the adrenal gland?
1) Capsule
2) Zona glomerulosa
3) Zona fasciculata
4) Zona reticulata
5) Medulla
What hormone does the zona glomerulosa respond to?
Angiotensin II
What hormones do the zona reticulata and fasciculata respond to?
ACTH and CRH
Which arteries supply the adrenal glands?
Suprarenal arteries
Which hormones do the adrenal medulla produce?
epinephrine and norepinephrine
What type of cells are in the adrenal medulla and from where do they come from?
1) chromaffin cells
2) modified post-ganglionic sympathetic fibers
What innervates the adrenal medulla?
preganglionic sympathetic
Where is CRH made in the hypothalamus?
paraventricular nucleus
Which second messenger does CRH work through?
cAMP
Which corticosteroids are activated by CRH?
all of them
Which corticosteroids exert negative feedback on the hypothalamus?
cortisol
Which corticosteroids exert negative feedback on the anterior pituitary?
cortisol
What type of release does ACTH follow?
diurnal and pulsatile
Which protein is ACTH derived from?
POMC
When ACTH is chronically elevated, what morphological change to the adrenal gland happens?
hypertrophy of adrenal cortex
Hypertrophy of the adrenal cortex leads to what biochemical change?
Increase in LDL-Rs and increased transcription of steroid hormone synthesis enzymes
What is a side effect of chronically elevated ACTH?
increased melanin synthesis due to alpha-MSH
What is the purpose of StAR protein?
Shuttles cholesterol from the cytosol to the mitochondria
Adrenocortical cells have which type of receptor?
lipoprotein receptors
Where does most cholesterol for the synthesis for steroid hormones come from?
circulating cholesterol
What is the first metabolite for steroid hormone synthesis that cholesterol turns into?
pregnenolone
What are the two main physiologic consequences of aldosterone release?
Increased sodium resorption and increased potassium secretion
Aldosterone also controls fluid balance, how?
Through sodium resorption, leading to water retention
What is the major physiologic regulator of aldosterone?
angiotensin II
Other than Ang II, what else stimulates aldosterone?
hyperkalemia
What stimulates angiotensin II production?
Decrease in blood volume
What second messengers do angiotensin II work through? What about hyperkalemia?
IP3/DAG/Ca
Hyperkalemia works through calcium
What are the two main functions of aldosterone?
1) maintain blood volume
2) regulate hydrogen and potassium secretion
Which cells are acted upon by aldosterone?
principal cells of the distal tubule and collecting duct
The hydrogen-potassium exchanger functions mostly where?
collecting duct
What controls the rate of aldosterone production?
renin release from the kidney
What is primary hyperaldosteronism also called?
Conn’s syndrome
What physiological symptoms is NOT present in hyperaldosteronism that you would expect to be present? Why?
EDEMA, because of an “aldosterone escape mechanism”
What is the difference between primary and secondary hyperaldosteronism?
Primary: high aldosterone, low renin
Secondary: high aldosterone, high renin
What is the cause of primary hyperaldosteronism? Secondary hyperaldosteronism?
Primary: adrenal adenoma, idiopathic hyperplasia
Secondary: renovascular HTN, juxtaglomerular cell tumor
What are the four main symptoms of hyperaldosteronism?
1) hypertension
2) hypokalemia
3) alkalosis
4) decreased renin secretion
What causes the hypertension in hyperaldosteronism? How about the hypokalemia?
HTN: increase in ECF volume due to increase sodium reabsorption
Hypokalemia: increased potassium secretion in urine
What are the three main symptoms of hypoaldosteronism?
1) hyperkalemia
2) metabolic acidosis
3) hyponatremia
