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51 Cards in this Set
- Front
- Back
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What are steroid hormones made from?
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Cholesterol - 27C
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What is the cholesterol derivative precursor for steroid hormones? How many carbons?
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Pregnenolone - 21C
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What are the 5 classes of steroid hormones? How many C's?
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Progestins = 21C
Glucocorticoids = 21C Mineralcorticoids = 21C Androgens = 19C Estrogens = 18C |
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How do steroid hormones differ? (2 ways)
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1. Number of Carbons
2. Extent/position of OH groups |
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What hormones are derived from:
-Amino acids -Polypeptides -Cholesterol |
AA = thyroxine
PP = insulin Cholesterol = steroids |
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What are the major steroid hormone producing organs?
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-Adrenal cortex
-Ovaries -Testes |
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Which is the more important organ? Why?
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Adrenal cortex - produces all 5 classes of steroid hormones.
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What stimulates steroid synthesis in adrenal cortex?
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ACTH - stimulates adrenal cortex, produced by Ant. pituitary.
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What is the mechanism of hormone action?
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Stimulation of organ activity via specific RECEPTORs.
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Glucocorticoids:
-Major site of synthesis -What hormones? -Primary target tissue |
Synth: Adrenal cortex
Hormones: Cortisol, cortisone, corticosterone Targets: Muscle/Liver |
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-Primary target tissue & Effects of Glucocorticoids:
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Targets: Muscle/Liver
-Protein catabolism (fasting state) -Gluconeogenesis -Anti-inflammatory |
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Mineralcorticoids:
-Major site of synthesis -What hormones? -Primary target tissue |
Synth: Adrenal cortex
Hormones: Aldosterone, 11-deoxycorticosterone |
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-Primary target tissue & Effects of Mineralcorticoids:
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Target: Kidney tubules
-Sodium retention -Potassium excretion Indirectly increases BVol+BP |
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Androgens:
-Major site of synthesis -What hormones? |
Synth: Testes
Hormones: Testosterone |
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-Primary target tissue & Effects of Androgens:
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Target: Reproductive organs and muscle.
-Spermatogenesis -2ndary male characteristics, -Bone maturation -Virilization |
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Estrogens
-Major site of synthesis -Hormones in this class |
Synth: Ovary
Hormones: Estradiol, Estrone |
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Primary target tissues and effects of Estrogens:
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Targets: Reproductive organs
Effects: -Feminization -Cyclic rythms -Maintains bone density |
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Progestins
-Major site of synthesis -Hormone in this class |
Synth: Ovary Corpus Luteum
Hormone: Progesterone |
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Primary target tissues and effects of Progestin:
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Target: Uterus
Effects: -Nidation -Cyclic rythms -Maintains pregnancy |
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Nidation is
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Preparation of uterine lining for ovum implantation
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Common use of Glucocorticoids in high doses?
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Anti-inflammatory
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How do Androgens affect muscles?
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Increase muscle mass
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What are 4 common clinical uses of steroid hormones?
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1. Topical - skin disease
2. Hormone replacement therapy (estrogen) 3. Anti-inflammatory Agents 4. Anti-rejection therapy |
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What is the common Hormone replacement therapy?
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Estrogen - for menopause and to prevent osteoporosis.
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What steroid hormone is a common anti-inflammatory agent?
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Corticosteroids - at HIGH nonphysiological doses.
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What often develops in Transplant patients on anti-rejection therapy? Why?
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Hyperlipidemia due to:
-Increased HMGCoA Reductase -Decreased LDL receptors |
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What can happen to chronic users of corticosteroids (3 effects)?
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1. Severe infection
2. Bone necrosis 3. Incr. severity of Diabetes |
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Why do athletes use anabolic steroids?
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Because it builds muscle mass
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What are bad side effects of Anabolic steroids?
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Kidney/liver disorders
Heart disease |
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What is the common Hormone replacement therapy?
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Estrogen - for menopause and to prevent osteoporosis.
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3 Zones of the Adrenal Cortex:
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-Glomerulosa (outermost)
-Fasciculata -Reticularis (medulla innermost) |
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First step in steroid hormone production:
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Convert Cholesterol to Pregnenolone
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Enzyme for Pregnenolone synthesis:
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Desmolase
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Desmolase - what kind of enzyme?
Another name? |
Monooxygenase enzyme
"Cytochrome P450scc" scc = side chain cleavage |
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Where is Desmolase located?
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on inner mitochondrial membrane, matrix side.
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What does Desmolase require for reaction?
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3 molecules of NADPH
3 molecules of O2 |
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2 types of Cytochrome P450 in the mitochondria:
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-P450scc
-P45011B (beta) |
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General reaction catalyzed by cytochrome P450's:
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RH + O2 + NADPH + H+ --> ROH + H2O + NADP+
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What pathway is especially ramped up in steroidogenic tissues?
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PPP = hmp shunt
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What is essential for the action of P450 enzymes?
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An electron transport chain
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What are the 4 electron shuttles that make up mitochondrial ETC?
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-NADPH
-Adrenodoxin reductase -Adrenodoxin -P450scc or 11B |
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What happens when electrons get to the heme group of P450scc?
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Activate O2 to hydrolyze a 6-C side chain off cholesterol, which makes Pregnenalone.
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What cofactor is used by
-Adrenodoxin reductase? -Adrenodoxin? -Cyto P450? |
Adrndxn reductase = FAD
Adrenodoxin = Iron-Sulfur group Cytochrome P450 = Heme ring |
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Which shuttler is mobile?
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Adrenodoxin
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Where are Glucocorticoids made?
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Adrnl cortex - Zona Fasciculata
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In which cell compartments are glucocorticoids made?
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-Mitochondria
-Endoplasmic reticulum |
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What are the 3 sources of Cholesterol for glucocorticoid synthesis?
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-De novo synth via AcCoA (minor)
-High LDL receptor expression -SR-B1 receptor (HDL) |
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What is the difference between ETC's used for mitochondrial versus ER P450 enzymes?
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Mito: requires 2 proteins between NADPH and P450scc
ER: only one protein needed (no adrenodoxin FeSulfur protein). |
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What is the name of the protein used in place of Adrenodoxin in the ER etc for P450?
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NADPH Cytochrome P450 Reductase
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What is the cofactor used by NADPH Cyto P450 Reductase?
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Flavin (FAD)
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So what is the first step of glucocorticoid synthesis? Where?
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Conversion of Cholesterol to Pregnenalone in Mitochondria.
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