Physiology Of The Adrenal Gland

Question 1

What is the rate limiting step in the synthesis of all corticosteroids

Answer 1

Cholesterol → pregnelolone via P-450ssc

Question 2

Name the 4 main hormones produced in the adrenal cortex and state which layer their are produced in

Answer 2

1. Aldosterone in the zona glomerulosa
2. Cortisol in the zona fasciculata
3. DHEA and androstendione in the zona reticularis

Question 3

What is DHEA & androstendione converted to in the peripheral tissues & what enzymes allows this

Answer 3

Testosterone & dihydrotestosterone
In peripheral tissue by 5⍺ reductase

Question 4

Describe the HPA axis

Answer 4

Hypothalamus secretes corticotropin releasing hormone
Anterior pituitary secretes ACTH
Adrenal cortex secretes cortisol (& androgens)

Question 5

Describe the control of the HPA axis

Answer 5

Negative feedback control by cortisol on anterior pituitary & hypothalamus
But also CRH secretion influence by stress, illness & time of day

Question 6

What regulates aldosterone secretion

Answer 6

The RAAS system
High AII & low K+

Question 7

Briefly describe the RAAS system

Answer 7

Drop in blood pressure →
Kidneys release renin →
Angiotensinogen converted to angiotensin I →
Angiotensin I converted to angiotensin II by ACE →
Aldosterone secreted by adrenal cortex →
Salt retention & Increase in BP

Question 8

What is secreted by the adrenal medulla

Answer 8

Adrenaline & noradrenaline

Question 9

What is adrenaline & noradrenaline produced from

Answer 9

Tyrosine that forms dopamine that then forms NA or A