Flashcards in The Adrenal Gland Deck (107)
What is the adrenal gland?
a hybrid gland consisting of a cortex and a medulla
What is important about the hormones of the adrenal gland?
regulators of metabolism and adaptation to stress
What is cortisol?
glucocorticoid which increases plasma glucose levels
What is aldosterone?
mineralocorticoid promotes salt and water retention by the kidney
What else is secreted by the adrenal cortex?
weak androgens which can be converted to testosterone
What are the products of chromaffin cells?
epinephrine but also produces small amounts of norepinephrine
What are steroid hormones derived from?
cholesterol - different ring structures and side chains
What is the common features of steroid hormones?
lipid soluble so are freely permeable
How are steroid hormones are carried in the blood ?
complexed to binding globulins - corticosteroid binding globulin binds cortisol
Where are the enzymes that produce steroids from cholesterol?
in the mitochondria and smER
What are the sources of free cholesterol in the cell is maintained relatively constant?
cellular synthesis of cholesterol from acetate
LDL -> esterified cholesterol from LDL droplets inside the cell
What is the rate limiting step in steroidogenesis?
the transport of free cholesterol from the cytoplasm to the mitochodria
How is cholesterol carried into the mitochondria?
Steroidgenic Acute Regulatory Protein (StAR)
What is cholesterol converted to in the inner membrane?
pregnenolone by CYP450scc -side chain cleavage aka desmolase
Where does cholesterol conversion occur?
in the adrenal, ovary and testis
What converts pregnenolone to 17a-hydroxypregnenolone?
What converts pregnenolone and pregesterone to mineralocorticoids?
Where is CYP17 found?
not in glomerulosa
Where is CYP11B2 found?
only in the glomerulosa
What is synthesised in the fasiculata?
Which enzyme esterifies free cholesterol?
acyl coA cholesterol transferase
Which enzyme turns lipid droplets back into cholesterol?
hormone sensitive lipase
What increases the activity of hormone sensitive lipase?
How many reactions modify cholesterol to cortisol?
What is the first enzyme in the modification of cholesterol to cortisol and where is it located?
inner mitochondrial membrane
How is the activity of StAR increased?
ACTH stimulates Gs -> cAMP-> PKA which phosphorylates StAR
How is cortisol predominantly transported in the blood?
CBG - 90%
albumin - 5-7%
What does the unbound form of cortisol do?
exerts its effects on tissues and feedsback on the pituitary and hypothalamus
What does the liver conjugate cortisol with?
gluconoride or sulfate