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15 Cards in this Set
- Front
- Back
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What are all steroid hormones synthesised from? |
Cholesterol |
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How much cholesterol is synthesized and ingested each day? |
Synthesized - 1g Ingested 500 mg |
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How is cholesterol transported? |
In serum as LDL or VLDL
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What are the three groups of steroid hormones?
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Corticosteroids Androgens Estrogens |
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Where does steroid synthesis occur? |
Adrenal cortex, ovaries, testes
Mi or ER CYP11 gene family, cytochrome P450 oxidase |
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Which enzyme expression is required for cortisol or sex hormones secretion? |
17a -hydroxylase |
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Which reaction does P450 oxidase catalyse? |
Hydroxylation
RH + O2 +NADP + H+ TO ROH + H2O + NADP+ |
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Where is cortisol secreted from?
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Zona fasciculata
Lesser extent - zona reticularis |
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How is cortisol found in blood ? |
75 % - bound in plasma to corticosteroid binding globulin
15% serum albumin 10 % free |
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How does cortisol affect cells? |
Lipid soluble, enters target cell
Binds specific receptors in cytoplasm Receptors dimerise, binds DNA OR Non-genomic effects by cell surface receptors |
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What is the effect of cortisol on metabolism? |
Adipose tissue- increases lipolysis - releases FFAs Muscle - catabolism, release of aa Inhibits glucose uptake Liver - gluconeogenesis via expression of phosphoenolpyruvate carboxykinase and glucose-phosphatase |
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Overall effect of cortisol on metabolism? |
Increase blood glucose levels
- insulin stimulation of glycogen storage and synthesis |
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Illustrate the effect of cortisol on metabolism |
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What are the effects of Cortisol on immune system? |
Anti-inflammatory responses- increases PMN leukocyes, reduces cirulating lymph, mono, eosin. Inhibits phospholipase A2- blocks prostaglandin synthesis |
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How is cortisol regulated? |
Adrenocorticotrophic hormone from anterior pituitary The 7-TM ACTH receptor activates adenylyl cyclase- rise in cAMP, activates PKA, activates cholesterol ester hydrolase- releases cholesterol from esterified stores in cells |
