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48 Cards in this Set
- Front
- Back
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Principal mineralcorticoid
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Aldosterone
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Principal glucocorticoid
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Cortisol
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Secretion of zona glomerulosa is controlled mainly by?
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ECF concentrations of Angiotension II and K+...stimulates aldosterone synthase to make aldosterone.
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Middle and largest layer of adrenal cortex
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Zona fasciculata:
Cortisol and corticosterone...as well as small amounts of adrenal androgens and estrogens |
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Control of zona fasciculata secretions is mainly from?
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ACTH
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Deep layer of cortex secretes? Regulated By?
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Zona reticularis:
Secretes DHEA and androstenedione ACTH |
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Most cholesterol used for steroid synthesis is derived from?
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LDL
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How are LDL's brought into the adrenal cortex?
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They bind to coated pits on the adrenocortical cell membranes. The coated pits are then endocytosed, and form vesicles that fuse with cell lysosomes and release cholesterol
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Increases the the number of adrenocortical cell receptors for LDL, as well as the activity of enzymes that liberate cholesterol from LDL
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ACTH
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What happens once cholesterol enters zona fasciculata cells?
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It is deleverd to mitochondria, where it is cleaved by cholesterol desmolase to pregnenolone.
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Rate-limiting step in steroid synthesis of all 3 zones of adrenal cortex
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Cholesterol to pregnenolone via cholesterol desmolase. This occurs in all 3 zones, thus both ACTH and angiotensin II increase production of pregnenolone
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Increases productions of pregnenolone
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ACTH
Angiotensin II |
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Accounts for 90% of mineralcorticoid activity
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Aldosterone
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Aldosterone synthesis
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1. Cholesterol to pregnenolone via cholesterol desmolase
2. Pregenolone to progesterone 3. Progesterone to 11-deoxycorticosterone via 21B-Hydroxylase 4. 11-Deoxycorticosterone to corticosterone via 11B-hydroxylase 5. Aldosterone via aldosterone synthase |
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Cortisol synthesis
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Cholesterol
Pregnenolone Progesterone----17a-hydroxylase 17-Hydroxyprogesterone---->21B-hydroxylase 11-deoxycortisol--->11Bhydroxylase Cortisol |
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Function of 21b-hydroxylase
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1. Progesterone---->11-deoxycorticosterone
2. 17a-hydroxyprogesterone----> 11-deoxycortisol |
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An absence of 21b-hydroxylase would cause excess production of?
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Androstendione via concersion of Progesterone to 17-alphahydroxylase to andro(17,20 Lyase)
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Function of 11b-hydroxylase
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1. 11-deoxycorticosterone to corticosterone
2. 11-deoxycortisol to cortisol |
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Androstenedione synthesis
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Pregnenolone to 17-hydroxypregnenolone to DHEA to andro
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Synthetic potent glucocorticoids
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Cortisone
Predisone Methylprednisone Dexamethasone(extremely potent) |
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Metabolism of adrenal steroids? Fate?
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Conjugated in the liver to glucuronic acid...most are not excreted in the bile, but rather are excreted in the urine.
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Does cortisol have mineralcorticoid activity?
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Yes, thus in excess, it may have potent mineralcorticoid effects.
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Most cortisol in the plasma is in what form
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Bound to transcortin, cortisol bining globulin
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transcortin
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cortisol binding globulin
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Best-known metabolic effect of cortisol? How?
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stimulates gluconeogenesis by the liver:
1. Activates DNA transcription in the liver nuclei, with formation of RNA proteins that form enzymes required for gluconeogenesis. 2. Causes mobilization of AA's from muscle, which enter into gluconeogenesis |
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Cortisols effect on glucose utilization?
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Decreased:
Due to decreased NAD+, which is needed for glycolysis |
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Glucocorticoids affects on insulin? Most influence where? How?
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Increases the secretion of insulin, but decreases its effectiveness.
Skeletal muscle and adipose tissue High levels of fatty acids, from mobilization of fats, cause impaired insulin effectiveness. |
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Where within the body does cortisol increase proteins?
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Liver and plasma proteins:
Cortisol enhances AA transport into liver cells and enhances liver enzymes required for protein synthesis. |
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Cortisols effect on protein. Affects on AA transport. How?
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Reduction of protein stores in all cells of the body except the liver:
Results from decreased AA transport into extrahepatic tissues, causing decreased protein synthesis. Further, cortisol continues to mobilize AA's from tissues for enhanced protein synthesis and gluconeogenesis. Cortisol also depresses formation of RNA. |
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Many of the effects of cortisol on the metabolic systems of the body result mainly from?
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The ability of cortisol to mobilize AA's from the peripheral tissues while at the same time increasing liver enzymes.
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Cortisol's effects on Fatty acids
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Increases fatty acid mobilization from adipose tissue. This increases the free fatty acid concentration. This is due to diminished transport of glucose into cells, which reduces alpha-glycerolphosphate, needed for deposition and maintenance of triglycerides.
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Types of stress that increase ACTH secretion from the ant pituitary
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Trauma
Infection hypothermia Injection of Norepi Surgery Injection of necrotizing substances Debilitating disease |
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Why is ACTH increased during stress?
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Increases energy supplies and supplies for synthesis of other compounds...such as proteins, purines, pyrimidines...
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Inflammation causes what type of edema
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Non-pitting:
Leakage of large quantities of plasma out of the capillaries, into the damaged area because of increased capillary permeability, then clotting of the tissue fluid. |
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Increase in blood flow to an area caused by released inflammatory products from damaged tissue
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erythema
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One of the most important effects of cortisol on inflammation?
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Stabilization of lysosomal membranes. Therefore, proteolytic enzymes that are released by damaged cells are reduced.
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Other effects of cortisol on inflammation, besides lysosomal membrane stabilization
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1. Decreases the permeability of the capillaries
2. Decreases migration of WBC's and phagocytosis. 3. Suppresses T lymphocyte production 4. Attenuates fever by reducing IL-1 release. This also decreases the degree of vasodilation. |
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How does cortisol effect the rate of healing?
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Enhances it:
Mobilization of AA's, and glucose and FA's for energy and production of cellular products to repair damaged tissues. |
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Cortisol may be used to treat what inflammatory diseases?
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Rheumatoid arthritis
rheumatic fever glomerulonephritis |
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How may cortisol attenuate allergic rxns
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Does not affect the basic rxn between antigen and antibody, but it blocks the serious inflammatory affects that may cause anaphylaxis.
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Secretion of cortisol is controlled by?
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ACTH from the anterior pituitary
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Controls ACTH secretion. Pathway?
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CRF from the hypothalamus. Secreted into the primary capillary plexus of the hypophysial portal system in the median eminence of the hypothalamus and then carried to anterior pituitary.
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Principal affect of ACTH on adrenocortical cells to produce steroids is?
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Activate adenylyl cyclase to produce cAMP
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Important diagnostic criteria for overproduction of cortisol
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Lymphocytopenia and eosinopenia due to decreased production.
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What are the functions of the zona pellucida? (4)
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Prevents polyspermy
prevents premature implantation prevents two zygotes from sticking together keeps blastomeres together until compaction |
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Most important of all the ACTH-stimulated steps for controlling adrenocortical secretion is?
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Activation of protein kinase A, which causes conversion of cholesterol to pregnenolone. The rate-limiting step.
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How does mental stress increase cortisol prodction?
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Stimulates the limbic system, especially the amygdala and hippocampus, to transmit signals to the posterior medial hypothalamus
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Pain stimuli stimulate what portion of the hypothalamus
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median eminence
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