Adrenal Gland Physiology Flashcards
Zones of adrenal cortex
anatomically in 3 zones but functionally as 2
- Zona Glomerulosa
- Zona fasciculata
- Zona reticularis
- latter two function more as a unit
what does zona glomerulosa produce
mineralcorticoids –aldosterone
hormone produced by zona fasciculata
glucocorticoids– most importantly cortisol
hormone produced by zona reticularis
sex steroids– androgens (DHEA-S)
Is the adrenal gland proportionally larger in fetus or adult
fetus
what is different about fetal adrenal gland
larger and has additional region/fetal zone– large inner zone
- important source of precursor for estrogen synthesis by placenta
- 3 zones (glomerulosa, fasciculata, reticularis) found in subcapsular area
precursor of adrenal hormones
cholesterol
from what is adrenal hormone precursor mostly
circulating LDL that bind plasma membrane receptors – internalized
- once in cell, cholesterol is removed, esterified, and stored in lipid droplets
How does cortex get cholesterol
endocytosis of circulating LDL; also can make it from acetyl Co-A (not major source)
In women what is main source of female androgens
adrenal gland vs testis in men
synthetic path of closterol
cholesterol—-pregenolone– 17 hydroxypregenolone- dihydroepiandosterone
- pregnenolone – mineralcorticoids (aldosterone)
- 17-hydroxypregenolone – glucocorticoids (cortisol)
- Dihydroepiandosterone (DHEA)– Sex steroids (Androgens)
how are cortex zones functionally specialized
each make different hormones by controlling levels of various enzymes
-i.e. glomerulosa doesn’t contain 17hydrozylase
immediate stress response due to what hormones
norepinephrine/epi
longer stress response due to what hormone
cortisol
metabolic fxns of cortisol
- glucose - increase in glucose via gluconeogenesis; antagonizes nsulin action (counterregulatory hormone)
- Proteins: proteolysis of skeletal muscle
- Lipids- increases FFA; mobilizes fat to central areas – centripetal distribution of fat (Mood facies; Buffalo Hump)
Actions of cortisol on heart/blood
polycythemia and increased beta adrenergic effects due to increased adrenergic receptors and release of adrenaline(aka permissive effects)
permissive effects
when facilitating action of another hormone
action of cortisol on bone
vitamin D antagonist– leads to decreased calcium and mobilization from bone to cause osteoporosis
action of cortisol on fibroblasts
decreases fibroblast number and decreased collagen synthesis– leads to easy bruisability and skin thinning
cortisol effects on inflammation
- anti-inflammatory
- inhibits phospholipase A2 – decreasing arachidonic acid and thus production of proxaglandins, thromboxanes, and leukotrienes
- inhibits vascular permeability changes and inhibiting fibroblast proliferation and thus sealing of wound
phospholipase A2 action
enzyme that breaks down membrane phospholipids to provide second messenger arachidonic acid, which is precursor for prostaglandins, thromboxanes, leukotrienes
is cortisol helpful in internal inflammation or external injury
internal inflammation–external injury would prevent wound healing
cortisol action on immune system
immunosuppression
- decrease T cell proliferation and activation
- inhibits IL-2 (T cell growth factor)
- inhibits histamine release
when might you use cortisol for its immune system effects
transplant of organs to decrease rejection
