8 - The adrenals and their hormones

Question 1

Where are the adrenals glands?

Answer 1

on the superior poles of each of the 2 kidneys

Question 2

Describe the blood supply and drainage of the adrenal glands?

Answer 2

have many arteries BUT ONLY ONE VEIN

Question 3

Where do the right and left adrenal veins drain into?

Answer 3

right - into IVC

left - into renal vein —> IVC

Question 4

What are the layers of the adrenal gland?

Answer 4

cortex (outer part) consists of 3 zones
- zona glomerulosa
- zona fasciculata
- zona reticularis 
adrenal medulla (centre)

Question 5

What is produced in the different layers of the adrenal glands?

Answer 5

cortex - produces corticosteroids
- zona glomerulosa - aldostérone
- zona fasciculata - cortisol
- zona reticularis - sex hormones
adrenal medulla - catecholamines

Question 6

What is the pattern of cells in the different zones of the cortex?

Answer 6

zona fasciculata - cells line up as strings

zona reticularis - doesn’t have a pattern

Question 7

What are the 2 ways that blood passes through the cells?

Answer 7

• most of it passes through the cells (diffusion)

- there are some vessels which go through the cortex to get to the medulla

Question 8

What is the medulla of the adrenals made up of?

Answer 8

chromaffin cells (specialised post-ganglionic nerve fibres in a specialised form)

this means there is a part of the sympathetic NS where the cells innervated by the pre-ganglionic fibres will release their hormones (as hormones) into the general circulation

Question 9

What hormones are produced by the adrenal medulla?

Answer 9

CATECHOLAMINES:

• adrenaline (80%)
• noradrenaline (20%)
• dopamine (very low concs)

Question 10

What types of hormones are produced by the cortex? Give examples

Answer 10

CORTICOSTEROIDS
- mineralocorticoids e.g. aldosterone
GLUCOCORTICOIDS
- cortisol
SEX STEROIDS
- androgen
- oestrogens

Question 11

What hormones are produced from the gonads?

Answer 11

progestogens
androgens
oestrogens

Question 12

In the synthesis of adrenal cortisol hormones, what is the first conversion step?

Answer 12

cholesterol —–> pregnelonone

Question 13

What is progesterone a precursor of?

Answer 13

aldosterone

Question 14

What is the precursor of oestrogens?

Answer 14

androgens

Question 15

Compare the percentage of corticosteroids that are bounds to plasma proteins

Answer 15

a lot more aldosterone is unbound in the blood compared to cortisol
cortisol is a lot more more selective for CBG (corticosteroid binding globulin)

CORTISOL:
75% - bound to CBG
15% - albumin
10% - unbound
ALDOSTERONE:
60% - bound to CBG
40% - free/unbound

Question 16

What are the receptors for the different corticosteroids?

Answer 16

cortisol —-> glucocorticoid receptor
aldosterone —–> mineralocorticoid

HOWEVER, cortisol can also bind to mineralocorticoid receptors

Question 17

If cortisol binds to both kinds of receptors, why is aldosterone needed?

Answer 17

there are tissues within the body that exclude cortisol - aldosterone is required here

NOTE: the enzyme 11hsd2 metabolises cortisol and is present in these tissues (kidney and tissue_, therefore, aldosterone had major impacts here

Question 18

What part of the kidney nephron does aldosterone act on?

Answer 18

DCT and cortisol collecting duct

Question 19

What effect does aldosterone have on osmolality?

What effect does this have?

Answer 19

increases osmolality

this simulates the release of vasopressin, which works on the collecting duct to increase water reabsorption

(overall, the effect of aldosterone is an expansion of extracellular fluid volume)

Question 20

What condition usually has aldosterone as its most important clinical correlate?

Answer 20

hypertension

Question 21

What stimulus do macula dense respond to?

Answer 21

changes in the sodium ion concentration

Question 22

What do the juxta-glomerula cells produce?

Answer 22

Renin - an enzyme (important in the production of aldosterone)

Question 23

What does angiotensin II do?

Answer 23

• stimulates the zona glomerulosa to produce aldosterone

- a vasoconstrictor

Question 24

What is the main stimulus for cortisol?

Answer 24

stresssssssssss