Adrenocortical Hormones Flashcards
Adrenal medulla secrete
Epinephrine
Norepinephrine
Adrenal cortex secretes
Corticosteroids:
Mineralocorticoids
Glucocorticoids
Androgen
Principal mineralocorticoid
Aldosterone
Principal glucocorticoid
Cortisol
The zona glomerulosa secretes
via ensyme
Aldosterone
Aldosterone synthase
Aldosterone control is mainly by
ECF concentration of angiotensin II
ECF concentration of K
The zona fasciculata with widest layer spanning 75% of cortex secretes
Cortisol
Corticosterone
Adrenal androgen (small) and estrogen
Control of cortisol, corticosterone is through
ACTH
Deep layer of cortex zona reticularis secretes
Dehydroepiandrosterone DHEA
androstenedione
Estrogen
Control of DHEA and androstenedione is by
ACTH
Cortical androgen-stimulating hormone
Adrenocortical hormones are derived from
cholesterol provided by LDL 80%
In the mitochondria, cholesterol is cleaved by the enzyme
To form
Cholesterol desmolase
pregnenolone
*rate limiting step of all adrenal steroid formation
90-95% of cortisol is bound to proteins called
cortisol-binding globulin
transcortin
ACH are metabolized in the
Conjugated with
and excreted in the kidneys
Liver
glucoronic acid and sulfate
Kidney
Loss of aldosterone and mineralocorticoid secretion lead to severe
renal NaCl wasting
Hyperkalemia
Death from shock
Cortisol does not normally exert significant mineralocorticoid effect despite avidly binding to renal epithelial cells bec of the enzyme that converts cortisol to cortisone
11B hydroxysteroid dehydrogenase type 2
Blockage or loss of 11B hydroxysteroid dehy type 2 manifest witth substantial mineralocorticoid effect bec of excess aldosterone like effect despite low levels of latter
Apparent mineralocorticoid excess AME
AME tx
Licorice with glycyrrhetinic acid blocking 11B
Return to normal of salt and water excretion by kidneys as result of pressure natriuresis and diuresis despite rise in atrial pressure by aldosterone
Aldosterone escape
Excess aldosterone drives
K into cell causing hypokalemia
severe muscle weakness
Aldosterone also acts on sweat, salivary glands and colon by
Inc Na reabsorption and promoting K and H ion secretion
Spironolactone antagonizes activity of thhe complex
Aldosterone-MR
Amiloride targets protein inserted into luminal membrane of tubular cell by aldosterone
Epithelial sodium ch (ENaC)
Cortisol promotes gluconeogenesis by
1 inc enzymes req to convert AA to glucose in liver
2 mobilization of AA from extrahepatic tissues from muscle
Cortisol has this effect on glucose utilization bec of
Decreased
Depression of oxidation of NADH to NAD
Cortisol can also cause this effect on glucose conc
Hyperglycemia due to inc FA leading to insulin resistance
Adrenal diabetes
Cortisol has this effect on protein
Reduction of protein stores
Except in liver
Muscle wasting
but inc liver and plasma protein
Cortisol prevents inflammation by
1 stabilizing lysosomal membrane
2 dec permeability of capillary
3 dec migration of WBC into inflamed area and phagocytosis of damaged cell
4 supression of immune system causing dec T cell reproduction
5 attenuation of fever IL1
Cortisol exerts its effect by
Binding with receptor in cytoplasm and HRC then interacts with regulatory DNA sequence called glucocorticoid response elements to induce or repress gene transcription
ACTH acts on adrenal cells by
activating adenylate cyclase
Inc cAMP in cytoplasm
Activates intracellular enzyme causing formation of adrenocortical hormones
Activation of Protein Kinase A causing initial conversion of cholesterol to pregnenolone
ACTH also participates in the regulation of skin color as MSH does bec
they originate from a larger precursor Proopiomelanocortin POMC
