Adrenals and their Hormones 8

Question 1

Describe the rough anatomy of the Adrenals

Answer 1

They are located at the superior pole of the kidneys. They each have their own capsules and have many arteries supplying them but only one vein each. The right adrenal vein drains into the IVC and the left adrenal vein drains into the renal vein.

Question 2

Describe Specific anatomy of the Adrenals

Answer 2

Comprised of a medulla and a cortex. The cortex produces corticosteroids while the medulla produces catecholamines

Question 3

What are the sections of the cortex (from medulla out)?

Answer 3

Zona Reticularis
Zona Fasciculata
Zona Glomerulosa

Question 4

How does blood get to the various zones?

Answer 4

• Flows through the cells in each zones from the exterior of the gland
• There are some vessels which flow through the cortex to get to the medulla

Question 5

What is the medulla made of?

Answer 5

CHROMAFFIN CELLS and therefore associated to the produced catecholamines

Question 6

What type of hormone does the cortex produce?

Answer 6

Steroids (therefore they are corticosteroids)

Question 7

What does the medulla produce?

Answer 7

Catecholamines:

• Adrenaline (80%)
• Noradrenaline (20%)
• Dopamine (V.small amounts)

Question 8

What does the cortex produce?

Answer 8

Cortiocsteroids:

• Mineralocorticoids = aldosterone
• Glucocorticoids = Cortisol
• Sex Steroids = androgens/oestrogens

Question 9

Where is aldosterone produced?

Answer 9

Zona Glomerulosa

Question 10

What are Cortisol and androgens/oestrogens produced?

Answer 10

Zona Fasciculata and Reticularis

Question 11

What are adrenal cortical hormones synthesised from?

Answer 11

Cholesterol

Question 12

Describe Cortisol Synthesis

Answer 12

1) Cholesterol
2) Pregnenolone
3) 17alpha-pregnenolone
4) 17alpha-progesterone
5) 11-deoxycortisol
6) Cortisol

Question 13

Describe Aldosterone Synthesis

Answer 13

1) Cholesterol
2) Pregnenolone
3) Progesterone
4) 11-deoxycorticosterone
5) Corticosterone
6) Aldosterone

Question 14

Describe Sex hormone Sythesis

Answer 14

1) Cholesterol
2) Pregnenolone
3) 17alpha-pregnenolone
4) Dehydroepiandrosterone
5) Androstenedione
6) Testosterone

Then either:

• Oestrodiol
• Dihydrotestosterone

Question 15

What is the precursor to oestrogens?

Answer 15

Androgens

Question 16

Describe Cortisol Transport

Answer 16

• Corticosteroid Binding Globulin (CBG) (80%)
• Albumin (10%)
• Bioactive (10%)

Question 17

Describe Aldosterone Transport

Answer 17

• CBG (15%)
• Albumin (45%)
• Bioactive (40%)

Question 18

When is cortisol released?

Answer 18

It is released at different times of the day (more in the morning). It is also released in pulses (pulsatile rhythm) on top of circadian rhythm

Question 19

What receptor does aldosterone act on?

Answer 19

Mineralocorticoid receptor

Question 20

What does Cortisol act on?

Answer 20

Mineralocorticoid and Glucocorticoid Receptors

Question 21

How do tissues prevent Cortisol acting on Mineralocorticoid Receptors?

Answer 21

Some tissues have enzymes (kidney) that converts bioactive Cortisol to Cortisone (inactive). This enzyme is 11b-hydroxysteroid dehydrodgenase 2 (11bhsb2). This enzyme is present in the kidneys and the placenta

Question 22

What is the action of Aldosterone?

Answer 22

• STIMULATE NA+ RE-ABSORPTION in the distal convuluted tubule and cortical collecting duct.
• STIMULATES K+ AND H+ SECRETION in the distal convuluted tubule and the collecting duct. This is for pH regulation of blood.

Question 23

What is Aldosterone the end product of ?

Answer 23

Renin-Angiotensin System

Question 24

Where is Renin released?

Answer 24

In the nephron, Macula Densa cells on the distal convuluted tubule sense Na+ concentration. These are in close proximity to the granular cells that line the afferent arteriole. These cells communicate and cause the granular cells to release the renin.

Question 25

What causes Renin to be released from the granular cells?

Answer 25

• a decrease in perfusion pressure (detected by the granular cells)
• Renal sympathetic activity (the juxta-glomerular apparatus is innervated)
• Low Na+ detected by the Macula Densa which communicate to the Granular cells

Question 26

Process of the Renin-Angiotensin-Aldosterone system

Answer 26

1) Liver produces angiotensinogen
2) Renin (from the juxta-glomerulus apparatus) cleaves this to Angiotensin 1
3) ACE (high conc in lungs) cleaves this to Angiotensin 2
4) Angiotensin 2 stimulates the zona glomerulosa to produce aldosterone
5) Angiotensin 2 also stimulates vasoconstriction and regulates ions.
6) Corticotrophin enhances the system (has a permissive effect)

Question 27

Which two proteins does Aldosterone upregulate on the distal convuluted tubule and the collecting duct?

Answer 27

• Na+ channels in the tubule lumen membrane

- Na-k+ ase which is inserted into the interstitial membrane

Question 28

What are the metabolic effects of Cortisol?

Answer 28

Overall increase in blood glucose:

• increased hepatic gluconeogenesis
• stimulates glycogen turnover
• fat metabolism
• enhances glucagon and catecholamines
• some mineralocorticoid effects
• some renal and cardiovascular effects

Question 29

What are the physiological effects of Cortisol?

Answer 29

• reduces blood flow to skeletal muscle and fat tissue

- reduces entry of glucose into these tissues

Question 30

Whats another effect of Cortisol?

Answer 30

• enhances memory within the hippocampus

- it works with serotonin to proliferate granular cells in the hippocampus (more branches = better memory)

Question 31

Pharmacological effect of Large amounts of Cortisol?

Answer 31

• Anti-inflammatory
• Anti-allergic
• Immunosuppresive
  Increased by caffeine and alcohol levels

Question 32

Describe Cortisol control

Answer 32

The cortiocotrophs are controlled by hypothalamic neurones. Cortisol has a negative feedback affect on the pituitary and indirectly on the hypothalamus.

ACTH has an auto-negative feedback to the hypothalamus.

The circadian clock also control release