Ch. 574 - Physiology of the Adrenal Gland Flashcards
Adrenal cortex vs medulla: Chromaffin cells
Medulla
Adrenal cortex vs medulla: Derived from mesoderm
Cortex
Adrenal cortex vs medulla: Derived from ectoderm
Medulla, neuroectoderm
Adrenal cortex: outermost to innermost layers
Glomerulosa, fasciculata, reticularis
Most potent natural mineralocorticoid in humans
Aldosterone
Most potent natural glucocorticoid in humans
Cortisol
Adrenal cortex vs medulla: Sustentacular cells
Medulla
Hormone essential for fetal adrenal growth and maturation
ACTH
Starting substrate for all steroid biosynthesis
Cholesterol
Adrenal cortex can synthesize cholesterol de novo from
Acetate
Provide most of the cholesterol for adrenal cortex hormone formation
Circulating plasma lipoproteins
Rate-limiting step of adrenal steroidogenesis
Importation of cholesterol across the mitochondrial outer and inner membrane
Glucocorticoid secretion is regulated mainly by
ACTH
Pulses of ACTH and cortisol occur every ___
30-120 mins
Pulses of ACTH and cortisol are highest when
At about the time of waking
Pulses of ACTH and cortisol are low when
In the afternoon and evening
Pulses of ACTH and cortisol reach their lowest when
1-2 hrs after sleep begins
Most important stimulus for ACTH secretion
CRH
Rate of aldosterone synthesis is regulated mainly by
RAAS and K levels
Primary action of glucocorticoids on carb metab
Increases glucose by gluconeougenesis; OTHER mechanism - insulin resistance > decrease glucose entry into cells
Glucocorticoids: Effect on fatty acid metab
Increasee free fatty acids
Glucocorticoids: Protein metab
Catabolic or antianabolic
Glucocorticoids: Cardiac function
Positive inotrope > increase in LV work index
Glucocorticoids: Immune system
Generally an inhibitor; increases circulating PMNs mostly by preventing their egress from the circulation
Most significant effect of long-term glucocorticoid excess on Ca and bone metab
Osteoporosis
Major function of mineralocorticoids
Maintain intravascular volume by conserving Na and eliminating K and H+
Where mineralocorticoids exert most important actions
DCT and cortical collecting ducts (reabsorption of Na and excretion of K
In men ___% of biologically important androgens are derived from adrenal production, while in women ___% of androgens are adrenal in origin
2, 50
Principal hormones of the adrenal medulla
Dopa, Epi, NE
Measured to detect pheochromocytomas of the adrenal medulla and sympathetic NS
Urinary metanephrines and catecholamines
Epi vs NE: Increases MAP
Both
Epi vs NE: Increases CO
Epi
Epi vs NE: Increases SBP and DBP (by increasing peripheral vascular resistance) with only a slight reduction in pulse rate
NE
Epi vs NE: Decreases pulse rate and DBP (by decreasing peripheral vascular resistance)
Epi
