Adrenal Physiology

Question 1

What does each section of adrenal secrete?

Answer 1

G: Aldosterone
F: Glucocorticoids (cortisol)
R: DHEA
Medulla: NE/Epinephrine

Question 2

Adrenocorticoids are synthesized from ____ by _____

Answer 2

Adrenocorticoids are synthesized from cholesterol by cytochrome P450

Question 3

What are steps

Answer 3

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Question 4

Which hormone can only be made in one area of adrenal gland? Why?

Answer 4

Aldosterone can only be made in zona glomerulosa because only those cells have aldosterone synthetase

Question 5

What is the function of Aldosterone? (2) What are stimulants for Aldosterone release? (3)

Answer 5

Function of aldosterone: regulate blood volume, salt/water homeostasis

Stimulators: Angiotensin II, [K], ACTH (to lesser degree)

Question 6

What is the function of cortisol? (2) What are stimulants for cortisol release? (2)

Answer 6

Functions of cortisol: energy balance, CV/metabolic/immune homeostasis
Stimulators: ACTH, Arginine vasopressin (lesser stimulus)

Question 7

What is function of androgens? (1) What is stimulant for androgen release? (1)

Answer 7

Function: Regulate pubarche
Stimulator: ACTH

Question 8

What are functions of NE/epinephrine (2)

Answer 8

Regulate CV effects

Regulate bronchial dilation

Question 9

What is mechanism of Aldosterone?

Answer 9

Aldosterone binds mineralocorticoid receptor in distal collecting duct of principal cell
Moves to nucleus to stimulate transcription of Na/K channels–>More Na reabsorption, K/H+ secretion

Question 10

What are stimulants of CRH? (2)

Answer 10

Circadian rhythm, physical stressors

Question 11

What are stimulants of ACTH (3)?

Answer 11

CRH, inflammation, arginine vasopressin

Question 12

What are functions of ACTH? (2) Explain its melanogenic properties

Answer 12

Functions: Increase LDL receptors to bring in more cholesterol as precursor for steroidogenesis
Activate CYP11A1 enzyme for steroid cleavage

Functions as melanocortin by activating melanocortin 1 receptor on melanocyte (leads to skin pigmentation)

Question 13

Explain cortisol secretion pattern. When is it highest/lowest?

Answer 13

Circadian rhythm with pulsatility.

Highest 6-8 hours after sleeping and declines after awakening
Lowest at midnight

Question 14

What are cortisol actions?

Liver, skeletal muscle, adipose, Heart, vascular smooth muscle, immune, bone, medulla

Answer 14

Lots and lots…know list

Question 15

Explain cortisol-cortisone shunt

Answer 15

Mineralocorticoid receptor has higher affinity for cortisol than aldosterone
In kidney (aldosterone sensitive tissue), shunt cortisol to cortison

Question 16

Explain how cortisone is converted back to cortisol

Answer 16

Cortisone in liver (GCR rich tissue) is converted back to cortisol

Question 17

Explain pseudohyperaldosteronism and licorice

Answer 17

Licorice prevents inactivation of cortisol in kidney

Cortisol activates MCR–>hypertension and hypokalemia

Question 18

What are functions of DHEA and androstenedione?

Answer 18

DHEA: stimulates pubarche

Androstenedione: converted to testosterone and estrone in peripheral tissues

Question 19

Explain catecholamine synthesis

Answer 19

Tyrosine enters chromatin cells and is converted by TH to dopa. Dopa then converted to NE/epinephrine

Question 20

What is rate limiting step of catecholamine synthesis?

Answer 20

Tyrosin to DOPA via tyrosine hydroxylation

Question 21

What promotes NE to epinephrine conversion? How does it work?

Answer 21

Cortisol upregulates PNMT enzyme which converts NE–>Epinephrine

Question 22

How much of catecholamines does medulla secrete?

Answer 22

20% NE

80%epinephrine

Question 23

What do catecholamines bind? What are the locations and effects?

Answer 23

Bind adrenergic receptors (a1/a2/ß1/ß2)

Too many locations and effects to list

Question 24

Describe fight or flight response (7)

Answer 24

Mobilize fuels, redistribute blood flow, decrease urinary output/GI, increase HR/BP, increase activity of sweat glands, increase ventilation, dilation of pupils