9. Biochemical Synthesis of Steroid Hormones Flashcards
(23 cards)
Classify steroid hormones
Glucocorticoids Mineralocorticoids Androgens Estrogens Progestogens
What are the 3 zones without the cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
What is produced in the zona glomerulosa?
Mineralocorticoids
What is produced in the zona fasciculata?
Glucocorticoids
What is produced in the zona reticularis?
Sex hormones
What is produced in the medulla?
Catecholamines
What hormones are involved in the regulation of adrenal gland hormones?
CRH
ACTH
What protein controls the uptake of cholesterol into mitochondria?
StAR protein
How is cholesterol converted to pregnenolone?
Side-chains are cleaved
Catalysed by cytochrome P450
Requires NADPH and O2
What enzyme converts pregnenolone to progesterone?
3beta-OH dehydrogenase
Which enzymes convert progesterone to cortisol?
17,21,11 alpha-hydroxylase
Which enzymes convert progesterone to aldosterone?
21,11 alpha-hydroxylase
Aldosterone synthase
What are the metabolic functions of glucocorticoids?
- Stimulates gluconeogenesis
- Increases glycogen in the liver
- Acts against insulin
- Decreases AA uptake and protein synthesis outside of the liver
- Breaks down protein in muscle, skin, bone
- Increased uptake of AA by liver for gluconeogenesis
- Mobilisation of FAs
- Stimulates lypolysis in adipose
- Increased fat deposition on face and trunk
What are the actions of mineralocorticoids?
Na+/K+ ATPase
Facilitates uptake of Na+ and H2O from tubular lumen
What is Congenital Adrenal Hyperplasia?
Autosomal Recessive disorders of cortisol biosynthesis
No negative feedback to HPA axis
What does a deficiency in 3beta-OH dehydrogenase result in?
No glucocorticoids, mineralocorticoids, active androgens or oestrogens
Salt excretion in urine
Female-like genitalia
What does a deficiency in 17-a-hydroxylase result in?
No sex hormones or cortisol
All progesterone is converted to aldosterone
Hypertension (Na+ and water retained)
Female-like genitalia
What does a deficiency in 21-a-hydroxylase result in?
Can be partial or complete absence of mineralocorticoids and glucocorticoid absence
Overproduction of androgens
Masculinisation of external genitalia in females
Early virulisation in males
What does a deficiency in 11-B-hydroxylase result in?
Decreased serum cortisol, aldosterone, corticosterone
Increased production deoxy-corticosterone
Fluid retention leading to hypertension
Over-production of androgens
Masculinisation of external genitalia in females
Early virulisation in males
What are the effects of a cortisol deficiency?
Poor response to stress
Hypoglycaemia
Hyperpigmentation
What are the effects of an aldosterone deficiency?
Hyperkalaemia
Hyponatraemia
Disturbs cardiac rhythm
Hypotension
What are the effects of combined cortisol and aldosterone deficiency?
Vascular collapse
Shock
Death
Overproduction of ACTH leading to adrenal hyperplasia
How are CAHs treated?
Daily glucocorticoid and mineralocorticoid replacement
Restore volume, electrolyte and glucose imbalances
