Adrenal, Thyroid, Parathyroid Glands Flashcards
Endocrine Cells and Two types of Target Cells
endocrine cells = secrete products in circulation
target cells = distant acted by receptor-mediated signal
1 – require intracellular secondary messenger (transmembrane receptor)
2 – hormone bind to nuclear receptor after gene transcription (intracellular receptor)
Adrenal Gland Secretions
- mineralocorticoid hormones (cortex)
- glucocorticoid hormones (cortex)
- gonadocorticoid androgens (cortex)
- catecholamine nor/epinephrine (medulla)
Adrenal Gland Structure Out to In
capsule
cortex (zona glomerulosa, fasciculata, reticularis)
medulla
Blood supply of adrenal gland out to in
suprarenal artery
zona glomerulosa capillary bed
zona fasiciculata (adeno-cortical sinusoid)
zona reticularis
medulla (medullary arteriole - direct link)
central adreno-medullary vein
Structures of Adrenal Gland secrete and regulated by
zona glomerulosa = aldosterone (angiotension II)
– lipid, mito, “acini”
zona fasiciculata = cortisol (ACTH)
– lipid, mito, SER
– promote glucose secrete, suppress inflammatory
zona reticularis = androgens (ACTH)
– lipid, mito, SER
Adrenal medulla cells
chromaffin cells contain granules
- norepinephrine + epinephrine (sympathetic neurons)
- glucocorticoids –> PNMT –> NE to E
- E binds to chromogranins to be released
Thyroid gland shape and location
- under larynx, on top of trachea
- vascular with butterfly shape (2 lobes)
Thyroid structure
- follicles filled with colloid (store inactive thyroxin - T4)
- follicular epithelium (simple cuboidal)
- capillaries
Production of Thyroid Hormones
- pumps transport iodide across basal
- secrete thyroglobulin + thyroid peroxidase into colloid
- thyroid peroxidase oxidizes iodide, binds thyroglobulin
- uptake colloid droplet, proteolysis of iodothyroglobulin
- fuse with lysosome and release T3/T4 into blood
Thyroid Hormone Production Regulation
- pituitary release TSH = ↑colloid broken down to T3/T4
- T3/T4 inhibit release of TSH
- anti-TSH receptor antibody activates TSH receptor
- more T3/T4 made for metabolism = Graves’ disease
Role of Parafollicular Cells
- found between thyroid follicles
- secrete calcitonin = lower blood calcium levels, inhibit bone resorption (no osteoclasts)
Parathyroid Gland Cells and Their Roles
Chief cells (basophillic nuclei) = PTH
Oxyphil cells (dense nuceli, eosin cyto, mito) = ?
Role of PTH
increase calcium levels in serum (calcium homeostasis)
- bone (osteoclast differentiation)
- kidney (calcium re-absorption)
- gut (synthesis vitamin D = calcium uptake)
