Week 3- The Adrenal Gland Flashcards
Where are the adrenal glands found?
Just above the kidneys
How many adrenal arteries are there?
Lots (57)
How many adrenal veins are there?
1
Where do left adrenal veins drain?
Rénal vein
Where do right adrenal veins drain?
Inferior vena cava
What makes up the adrenal cortex?
Zona glomerulosa (outermost layer), fasciculata (middle layer) and reticularis (inner layer)
What does the adrenal cortex do?
Secretes corticosteroids
What does the adrenal medulla do?
Secretes catecholamines eg adrenaline/noradrenaline
What does the zona glomerulosa synthesize?
Aldosterone
What do the zona fasciculata and reticularis synthesize together?
Cortisol (androgens & œstogen)
What molecule do steroids come from?
Cholesterol
What are the 3 classes of corticosteroids?
Mineralocortocoids (aldosterone ) Glucocorticoids (cortisol) Sex steroids (androgens, œstrogens)
What is the essential characteristic a steroid must have?
It must come from cholesterol
Describe how aldosterone is synthesized
The side chain of cholesterol is cleaved creating pregnenolone
Pregnenolone is oxidized to progesterone via 3 beta hydroxylation steroid dehydrogenase
An OH group is added at position 21 (11 deoxy corticosterone)
An OH group is added at position 11 (corticosterone)
An OH group is added at position 18 (aldosterone)
How is aldosterone output controlled?
By regulating the enzymes that hydroxylate progesterone to produce aldosterone
What is the enzyme that converts pregnenolone to progesterone?
3 beta hydroxy steroid dehydrogenase
What is a main role of aldosterone?
Control of blood pressure
What stimulates production of renin?
A drop in blood pressure
What is the effect of angiotensin II on the adrenals?
Causes activation of 3 hydroxysteroid dehydrogenase, 21/11/18 hydroxylase and side chain cleavage enzymes so aldosterone is produced