Lecture 21 - Adrenal Hormones

Question 1

What are the different regions of the adrenal gland and their functions?

L21 S4

Answer 1

Medulla:

• secretes epinephrine and norepinephrine
• related to sympathetic nervous system

Cortex:
-secretes corticosteroids

Question 2

What is the rate limiting step for corticosteroid synthesis?

L21 S5

Answer 2

Cholesterol desmolase

Question 3

What are the characteristics of aldosterone, where is it secreted, and what does it do?

L21 S8

Answer 3

Major mineralcorticoid

Half-life of 20 minutes

Secreted by zona glomerulosa and is controlled by angiotensin II and K+

Affects electrolytes (mostly Na+ and K+):

• sodium reabsorption in principal cells of late distal tubule
• potassium secretion in principal cells of late distal tubule
• hydrogen secretion in intercalated cells of late distal tubule

Question 4

What are the characteristics of cortisol, where is it secreted, and what does it do?

L21 S10

Answer 4

Major glucocorticoid

Essential in stress response

Secreted by zona fasciculata and controlled by ACTH

Negative feedback response to CRH and ACTH

Highest before waking and lowest in the evening (circadian)

Question 5

What are the characteristics of androgenic hormones, where are they secreted, and what do they do?

L21 S11

Answer 5

19 carbon steroids and precursors to estrogens (18 C steroids)

Secreted as ketosteroids in urine

Produced in the zona reticularis

Question 6

What occurs in the lack and excess of aldosterone?

L21 S12

Answer 6

Lack:

• massive increase in K+ but massive decrease in Na+ and Cl-
• blood volume greatly reduced leading to decreased cardiac output

Excess:

• increase ECF and arterial pressure
• little change in Na+ but significant reduction in K+
• alkalosis due to H+ exchange for Na+

Question 7

What is ENaC?

L21 S15-16

Answer 7

Epithelial sodium channel

Stimulated by aldosterone

Question 8

What are the functions of glucocorticoids?

L21 S19-20

Answer 8

Stimulates gluconeogenesis:

• increases protein catabolism
• mobilizes AA’s
• increases lipolysis

Resists stress

Resists inflammation::
-inhibits IL-2

Inhibits immune response

Maintains response to catecholamines

Question 9

What is Addison’s disease?

L21 S23-26

Answer 9

Primary hypoadrenalism resulting from damage to adrenal cortex

Can result in:
-mineralocorticoid deficiency
—hyponatremia, hyperkalemia
—decrease cardiac output and BP
-glucocorticoid deficiency
—reduction of glucose, protein, and fat
—susceptibility to stress
-melanin disturbance

Question 10

What is Cushing’s disease?

L21 S27-28

Answer 10

Caused by excess ACTH or adenomas of adrenal cortex

Characteristics:

• increased cortisol and androgen levels
• buffalo torso
• moon face
• HTN
• increased blood glucose
• increased protein catabolism and muscle wasting