Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
- 3rd side (hint)
Cholesterol - Precursor of all classes of steroid hormones. What are the classes?
|
Glucocorticoids: Cortisol
Mineralcorticoids: Aldosterone Sex Hormones: Androgens, Estrogens, Progestins Note: Glucocorticoids and Mineralcorticoids are called corticosteroids |
There are 3 of them
|
|
Location of Secretion and Synthesis of steroid hormones
|
1.) Adrenal Cortex: Cortisol, Aldosterone, and Androgens
2.) Ovaries and Placenta: Estrogens and Progestins 3.) Testes: Testosterone |
There are 3 of them
|
|
Carriers of steroid hormones - both specific and nonspecific carriers
|
1.) Albumin (non-specific carrier)
2.) Corticosteroid-binding Globulin (Transcortin): Transports cortisol 3.) Sex Hormone-binding Protein: Transports Sex Hormones |
There are 3 of them
|
|
General synthesis of steroid hormones requires?
|
Shortening of the hydrocarbon chain and hydroxylation of the steroid nucleus
|
2 steps
|
|
Cholesterol is converted to ______ by enzyme _______?
What does it require? |
Pregnenolone (Parent compound of all steroid hormones) by a cholesterol side chain cleavage enzyme complex (desmolase [RATE LIMITING!!!] - a cytochrome P450 mixed function oxidase of the INNER mitochondrial membrane)
Requires NADPH and Molecular Oxygen |
|
|
Source of cholesterol substrates for steroid hormone synthesis
|
1.) Newly synthesized
2.) Taken up from lipoproteins 3.) Released from cholesteryl esters stored in the cytosol of steroidogenic tissues Note: steroid hormone synthesis consumes little cholesterol compared to bile acid synthesis |
|
|
Hydroxylation reaction of pregnenolone occurs where?
|
ER and Mitochondria
This is following the oxidation step of pregnenolone to progesterone. |
|
|
What are the different types of congenital adrenal hyperplasias (CAH)
|
1.) 3-β-Hydroxysteroid Dehydrogenase Deficiency
2.) 17-alpha-hydroxylase deficiency 3.) 11-β-hydroxylase deficiency 4.) 21-alpha-hydroxylase deficiency 5.) 5-alpha-reductase deficiency |
There are 5 of them
|
|
Describe 3-β-Hydroxysteroid Dehydrogenase Deficiency
|
1.) No glucocorticoids, mineralocorticoids, androgens or estrogens
2.) Marked salt excretion 3.) All patients have female genitalia 4.) Total lost of all 5 steroid classes 5.) Probably terminal unless given perhaps hormone therapy 6.) All will have female characteristics because of lack of testosterone |
|
|
Describe 17-alpha-hydroxylase deficiency
|
1.) No sex hormones or cortisol are produced
2.) Increased mineralocorticoids Sodium and fluid retention, hypertension 3.) All patients have female genetalia |
|
|
Describe 11-β-hydroxylase deficiency
|
1.) Decrease in cortisol, aldosterone and corticosterone
2.) Increased deoxycorticosterone, fluid retention, low renin hypertension 3.) Masculinization 4.) Making lots of testosterone 5.) 11-deoxycorticosterone has a very strong mineralcorticoid effect. Therefore, paradoxically build up aldosterone like activity. Causes sodium retention. Renin levels drop Causes hypertension because of Sodium retention. |
|
|
Describe 21-alpha-hydroxylase deficiency
|
1.) Most common
2.) Most common CAH, > 90% of all cases 3.) Partial (non-classic) and complete (classic) deficiencies known 4.) Production of cortisol and aldosterone blocked 5.) Lose retention of sodium and retain potassium 6.) Leads to heart arrhythmias 7.) Cortisol is necessary for vascular tone leading to hypotension 8.) Precursors shunted to androgen pathway 9.) Females are born with ambiguous genitalia, males display early virility 10.) Rapid growth, prematur bone fustion short adult stature 11.) Abnormal body hair (hersitism) |
|
|
5 Classes of Steroid hormones
|
Corticosteroids -
1.) Glucocorticoids (Cortisol, adrenals) Causes upregulation of glucose 2.) Mineralcorticoids (Adolsterone, adrenals) Sodium potassium ratio Sex Hormones - 3.) Androgens (testosterone, testes; androstenedione, andrenals) 4.) Estrogens (estrodiol, ovaries) 5.) Progestins (progesterone, corpus luteum |
|
|
Desmolase Complex
|
1.) Member of the p450 family of proteins
In general p450 involved with steroids, processing of bile, and detoxification 2.) Puts hydroxy groups on to make more soluble 3.) Mitochondrial 4.) At least two separate enzyme complexes 5.) Removal of 6C from cholesterol 6.) Product is pregnenolone (C27-->C21) 7.) Requires NADPH and molecular O2 required NADPH From HMP Shunt 8.) Regulated by cAMP levels (ACTH) Increases synthesis of desmolase. Increases synthesis in cholesterol esterase 9.) Removes the esterified fatty acid on the cholesteryl ester Therefore, increases free cholesterol for steroid synthesis **** process not enough to increase substantially cholesterol homeostasis. 10.) In adrenal cortex where ACTH is made can be turned off is a growth hormone that if not turned off can cause hyperplasia (adrenohyperplasia) |
|