The adrenal gland Flashcards
Where are the adrenal glands?
On the top of the kidneys
see diagram 4/58
What does the left adrenal vein drain into?
the renal vein
What does the right adrenal vein drain into?
IVC
How many veins do both adrenal glands have?
only one vein
but have many arteries
(see diagram 10/58)
Describe the microanatomy of the adrenal glands
Split into adrenal cortex + adrenal medulla
adrenal cortex:
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis (seems to be disappearing in humans)
What does the adrenal cortex secrete?
corticosteroids (e.g. cortisol)
mineralocorticoids (aldosterone) --> controls minerals [Na+ & K+] glucocorticoids (cortisol) sex steroids (androgens, oestrogens)
What does the adrenal medulla secrete?
catecholamines (e.g. adrenaline)
adrenaline/epinephrine (80%)
noradrenaline/norepinephrine (20%) [dopamine]
secreted by neuroendocrine/chromaffin cells
Which part of the adrenal cortex secretes aldosterone?
Zona glomerulosa
Which part of the adrenal cortex secretes cortisol (androgens, oestrogens)?
Zona fasciculata
Zona reticularis
Describe the microanatomy of the adrenal cortex.
Capsule Zona glomerulosa Zona fasciculata Zona reticularis -- medulla
(see diagram 17-18/58)
What is a steroid?
biologically active organic compound with four rinds arranged in a specific molecular configrations.
have 2 principal biological functions:
- membrane fluidity
- signalling molecules
What is the precursor for adrenal gland secretions?
cholesterol
27 carbons
What is an enzyme?
protein that catalyses a specific reaction
there are various enzymes present in cells
specific enzymes catalyse the synthesis of particular alterations to the molecule
How is aldosterone formed from Cholesterol?
cholesterol -> pregnenolone -> progesterone -> [21 Hydroxylase] 11 deoxycorticosterone -> [11 hydroxylase] corticosterone -> [18 hydroxylase] aldosterone
How is cortisol formed from Cholesterol?
cholesterol -> pregnenolone -> progesterone -> [17 hydroxylase] 17 hydroxy-progesterone -> [21 hydroxylase] 11 deoxy-cortisol -> [11 hydroxylase] cortisol
How is oestrogen formed from cholesterol?
cholesterol -> pregnenolone -> progesterone -> [17 hydroxylase] 17 hydroxy-progesterone -> sex steroids -> (androgens) -> (oestrogen)
What is the role of aldosterone?
Controls blood pressure, sodium and lowers potassium.
- Stimulates Na+ reabsorption in distal convoluted tubule and cortical collecting duct in kidney (and in sweat glands, gastric glands, colon)
- Stimulates K+ and H+ secretion, also in distal convoluted tubule and cortical collecting duct
increased sodium reabsorption + water reabsorption -> raising blood volume
major net effect: conserve body sodium by stimulating its reabsorption
(See diagrams 27-28/58)