Steroid Biosynthesis Flashcards
(30 cards)
What is the significance of progesterone?
Supports pregnancy and embryogenesis. It prepares the uterus for implantation and relaxes smooth muscle and decreases the maternal immune response
What happens to levels of progesterone before menstruation labor and lactation?
It decreases
What is desmolase?
enzyme that produces pregnenolone from cholesterol
What hormone regulates desmolase activity?
ACTH, it stimulates production of pregnenolone from cholesterol
Where is Desmolase found and what type of enzyme is it?
Found in steroid producing tissues and it is also known as Cytochrome P450
What is the most important biochemical intermediate that is used as a substrate to produce other steroid hormones?
Pregnenolone
What hormones can pregnenolone be used to make?
Progesterone Aldosterone Cortisol Testosterone Estradiol
What specific carrier protein carries most of the plasma glucocorticoid hormones and progesterone?
Corticosteroid binding globulin, it belongs to the serine inhibitor family of proteins
What releases renin?
Kidneys when low blood volume is detected
What does Renin do?
cleaves angiotensinogen from the liver into angiotensin I
What enzyme converts angiotensin I into angiotensin II?
ACE
What does aldosterone do and what triggers its release?
Angiotensin II stimulates release of vasopressin from pituitary and aldosterone from adrenal cortex. It acts on kidneys to cause an increase in Na and water resorption to increase BP
What receptor does aldosterone bind & activate?
Mineralocorticoid receptor, a nuclear receptor superfamily member
What two hormones binds with the highest efficacy to MR?
Highest is aldosterone and next highest is 11-deoxycorticosterone
What hormones can increase Na retention therefore increasing blood pressure?
Aldosterone 11-Deoxycorticosterone Testosterone Hydrocortisone Corrtisone
Primary aldosteronism?
Excessive levels of aldosterone from the adrenal glands, leads to conn syndrome. This leads to high blood pressure and can causes a loss of K and retention of Na
4 hallmarks of Conn syndrome?
Excessive secretion of aldosterone Retention of Na Loss of K Produces Htn
What causes adrenal hyperplasia?
Classic and non classic forms, both caused by deficiencies in adrenal enzymes used to synthesize glucocorticoids. Results in increased [production from adrenal gland of cortisol precursors and androgens
Mild congenital adrenal hyperplasia can result in:
life threatening sinus infections Life threatening pulmonary infections shortened stature orthostatic syncope Severe acne
How will a woman with mild congenital adrenal hyperplasia present?
- Hirsutism, excessive body hair on parts of body where hair is normally absent or minimal
- General oligomenorrhea, infrequent or light menstruation
- Infertility
How do you tell if a fetus is at risk for congenital adrenal hyperplasia?
You can use HLA haplotype or test amniotic fluid for excess cortisol precursors
How do you treat congenital adrenal hyperplasia?
Hormone replacement therapy
What accumulates if you have a deficiency of 21-hydroxylase?
Progesterone and 17-Hydroxyprogesterone build up
- 21-hydroxylase will convert progesterone and 17OH-progesterone into Aldosterone and Cortisol down the road
What happens if you have a deficiency of 11-B Hydroxylase?
Build up of 11-deoxycorticosterone and 11-deoxycortisol and lack of aldosterone and cortisol
- 11B hydroxylase will convert deoxycorticosterone and 11-deoxycortisol into aldosterone and cortisol
