Adrenal cortex (dave's notes only so far)

Question 1

What does the adrenal cortex secrete?

Answer 1

Glucocorticoids, mineralocorticoids, and ANP

Question 2

Where are glucocorticoids secreted from?

Answer 2

From the zone fasciculata and reticularis of the adrenal cortex, C21, primary glucocorticoid is cortisol

Question 3

What is cortisol synthesised from? What controls this?

Answer 3

Cortisol is synthesised from cholesterol de novo on an as needed basis. Under the control of ACTH

Question 4

What pathway leads to ACTH release?

Answer 4

CRH from the hypothalamus stimulates corticotrophs to release ACTH from the anterior pituitary

Question 5

What stimulates ACTH release?

Answer 5

Stress, hypoglycaemia

Question 6

What inhibits ACTH release?

Answer 6

Cortisol (negative feedback)

Question 7

What is the action of ACTH?

Answer 7

ACTH binds a specific receptor, couples a g-Protein which increases cAMP, this provides cholesterol as a substrate. ACTH also has a trophic action on the adrenal cortex

Question 8

Describe cortisol transport and give half life of cortisol

Answer 8

Cortisol is bound to CBG (transcortin) (75%), and albumin (15%), and 10% is free. Half life is approximately 90mins.

Question 9

What is glucocorticoids/cortisol metabolised into? How is it excreted?

Answer 9

Cortisol is metabolised into cortisone. It is inactivated in the liver, conjugated, and excreted by the liver.

Question 10

What is the action of glucocorticoids (mainly cortisol)

Answer 10

Cortisol acts via a receptor to the nucleus, stimulates transcription and increases synthesis of mRNAs

Question 11

What is the effect of cortisol /?glucocorticoids?

Answer 11

Increased protein catabolism, increased gluconeogenesis, anti-insulin effect, increases blood glucose

Question 12

What does cortisol suppress?

Answer 12

ACTH via negative feedback

Question 13

What requires cortisol to be able to work?

Answer 13

Other hormones e.g. adrenaline, glucagon, catecholamines ->bronchodilatation?

Question 14

Give four other effects of cortisol

Answer 14

Anti-inflammatory, anti allergy, increases platelets, neutrophils and erythrocytes, and increases Hcl and pepsin secretion

Question 15

How does cortisol have an anti-inflammatory and anti-allergic effect?

Answer 15

It decreases eosinophils, decreases antibody production and ?? decreases ?lymphoid organs.

Question 16

What is the primary mineralocorticoid?

Answer 16

Aldosterone - most important

Question 17

Where is aldosterone secreted from?

Answer 17

Aldosterone is secreted from the zone glomerulosa, ???C21 wtf,

Question 18

What stimulates aldosterone secretion?

Answer 18

Decreased ECF volume, Angiotensin II, and ACTH and K+ also have small effects on aldosterone secretion

Question 19

How does a decrease in ECF volume lead to aldosterone secretion?

Answer 19

Decreased ECF -> JG cells -> renin release->lysis ??angiotensinogen ->ANGT 1 ->ACE (lung) ->ANGT II

Question 20

How does angiotensin II lead to aldosterone secretion?

Answer 20

ANGT II -> stimulates adrenal to produce aldosterone ??via g-protein ->PpC

Question 21

What is the transport and metabolism of aldosterone?

Answer 21

Aldosterone is loosely bound to albumin, and is inactivated by conjugation and reduction

Question 22

What are the effects of aldosterone?

Answer 22

Aldosterone binds the aldosterone receptor causing synthesis of new mRNA leading to ?Na/K+ ATP-ase

Question 23

What are the effects of aldosterone on the kidney?

Answer 23

Aldosterone increases distal tubule reabsorption of Na in exchange for K+ and H+, therefore causes Na retention and K+/H+ loss

Question 24

What are the effects of aldosterone on the large bowel?

Answer 24

Similar to its effects on the kidney?

Question 25

What is ANP?

Answer 25

Atrial natriuretic peptide, a 28 amino acid protein found in the atria

Question 26

What increases secretion of ANP?

Answer 26

Increased CVP (and vice versa). Short half life.

Question 27

What is associated with a fall in aldosterone?

Answer 27

A rise in ANP

Question 28

What are the actions of ANP?

Answer 28

• ANP causes natriuresis? through mesangial cells affecting the GF area, or through tubular Na handling
• Lowers the BP by inhibiting several vasoactive substances
• decreases release of vasopressin
• decreases release of renin

Question 29

What are two congenital adrenal defects?

Answer 29

21 hydroxylase deficiency, 11 hydroxylase deficiency

Question 30

What does 21 hydroxylase deficiency cause?

Answer 30

Sodium loss

Question 31

What does 11 hydroxylase deficiency lead to?

Answer 31

Hypertension and increased sodium