Term
Where is cortisol produced?
What type of hormone is it?
What are its effects? |
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Definition
Cortisol is produced in the zona fasciculata and zona reticularis of the adrenal cortex
Glucocorticoid
Cortisol increases the glucose concentration in plasma |
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Term
Where is aldosterone produced?
What type of steroid hormone is it?
What are its effects? |
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Definition
Aldosterone is produced in the zona glomerulosa of the adrenal cortex
Mineralcorticoid
Aldosterone regulates Na+, K+, and water retention by the kidneys |
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Term
| How can the cholesterol used to synthesize hormones be obtained? |
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Definition
| It can be synthesized de novo from acetate (minor source) or it can be obtained from circulating low and high density lipoproteins that transport cholestrol (major source); cholestrol is esterfied and stored in lipid droplets |
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Term
| What type of enzymes are responsible for cholestrol conversion? |
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Definition
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Term
| What is the rate limiting step in steroid biosynthesis? |
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Definition
| C27 cholestrol being cleaved to C21 pregnenolone by the cholestrol side chain cleavage complex |
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Term
| Why is 17a hydroxylase important? |
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Definition
It is important for creation of cortisol and sex hormones
Deficiency could result in lack of seconday sex characteristics and low cortisol
17a hydroxylase is not present in significant quantity in the zona glomerulosa, which is why aldosterone is produced there |
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Term
| How does cortisol travel in the circulatory system? |
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Definition
90% binds to corticosteroid-binding globulin (CBG)
6% binds albumin
4% remains unbound
CBG has a 30 fold higher affinity for cortisol than aldosterone |
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Term
| What are some of the functions of cortisol? |
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Definition
| Plays a prominent role in the conversion of protein into glycogen, supporting a catabolic metabolism; Sustains gluconeogenesis, lipolysis, ketogenesis elicited by GH and epinephrine, ensuring metabolic stability overnight; Antagonizes insulin actions |
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Term
| How does cortisol affect the kidney? |
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Definition
| Increases glomerular filtration; increases Ca2+ and phosphate excretion by decreasing reabsorption in the proximal tubule |
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Term
| How does cortisol affect trabecular bone? |
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Definition
It increases bone resorption and osteoclast differentiation while decreasing osteocyte and osteoblast differentiation
Calcium absorption in the GI tract is diminished |
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Term
| How does cortisol affect the immune system? |
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Definition
Increases the release of neutrophils into the circulatory system but prevents neutrophil extravasation; cortisol suppresses the synthesis and release of arachidonic acid by increasing lipocortin
Cortisol causes the sequestration of circulating lymphocytes in the reticuloendothelial system (spleen, thymus, bone marrow); apoptosis of eosinophils and decreased proliferation of fibroblasts; cell-mediated immunity is greatly diminished |
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Term
| What is the pathway of glucocorticoid synthesis? |
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Definition
Hypothalamus
CRH
Anterior pituitary corticotropes
ACTH
Adrenal cortex
Cortisol |
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Term
| How would ACTH deficiency affect the adrenal cortex? |
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Definition
It would cause atrophy of the zona fasciculata and zona reticularis
ACTH serves as a trophic factor for the cells in these areas |
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Term
| When is the peak release of cortisol? |
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Definition
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Term
| What limits the rate of aldosterone secretion? |
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Definition
| Its rate of synthesis; it cannot be stored |
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Term
| What increases aldosterone synthesis? |
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Definition
ACTH does so modestly
Angiotension II and extracellular K+ concentration are the major regulators |
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Term
| What is Addison's disease? |
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Definition
Primary adrenal corticol insufficiency; complete destruction of the adrenal cortex due to autoimmune disease, infection, or cancer
Addison's disease usually occurs as a slow, progressive loss of cortisol and aldosterone secretion; symptoms include fatigue, high plasma potassium, low plasma sodium, low bp, hypoglycemia, hyperpigmentation, anorexia, and dehydration |
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Term
| What is Cushing's syndrome? |
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Definition
Chronic glucocorticoid excess
Symptoms include redistribution of fat from the extremities to the trunk, face, across the shoulder blades, and the base of the neck; thinning of skin; blood vessels appear closer to the surface; hypertension, hyperglycemic, increased susceptibility to infection |
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Term
| What serves as the substrate for the production of catecholamines? |
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Definition
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Term
| What is the rate limiting enzyme in the production of catecholamines? |
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Definition
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