peripheral endocrine system

2 cells of the thyroid glands

follicular cells and C-cells

function of the follicular cells

produce thyroid hormone (T4 and T3)

function of C-cells

produce calcitonin peptide hormone

synthesis of TH

follicular cells synthesize thyroglobulin which is exocytosed in the colloid, where iodione gets attached to it by enzyme peroxidase and becomes DIT and MIT

storage of TH

DIT and MIT are stored in the colloid until secretion. usually a months worth supply of TH is stored

secretion of TH

MIT and DIT re-enter the follicular cell via pinocytosis and T4 and T3 split from the thyroglublin by lysozyme enzymes and diffuse across the membranes

most produced form of TH

T4

most active form of TH

T3

adrenal cortex

outermost layer of the adrenal gland that secretes steroid hormoness

steroid homrones secreted by the adrenal glands

mineralcorticoids (aldosterone)

glucocorticoids (cortisol)

sex hormones

function of mineralcorticoids (aldosterone)

Na+/K+ balance

function of glucocorticoids (cortisol)

stimulate glucose metabolism as well as lipid and protein metabolism

outermost layer of the adrenal cortex

zona glomerulosa

function of the zona glomerulosa

secretes aldosterone

middle layer of the adrenal cortex

zona fasciculata

function of the zona fasciculata

secrete corisol and DHEA and is the largest portion of the cortex

inner most layer of the adrenal cortex

zona reticularis

function of the zona reticularis

secrete cortisol and DHEA

adrenal medulla

inner portion of the adrenal glands that secretes catecolamines

the adrenal medulla is a modified …

modified version of the post-ganglionic neuron s

stimulus for the adrenal medulla

SNS activated by stress

hormones that the adrenal medulla secretes

epinephrine and norepinephrine

cells of the endocrine pancreas

islets of langerhans

beta cells

secrete insulin

alpha cells

secrete glucagon

delta cells

secrete somatostatin

F cells

secrete pancreatic polypeptide hormone

sigma cells

secrete ghrelin

3 hormones that control calcium (and PO4) metabolism

parathyroid hormone (PH), vitamin D, and calcitonin

parathyroid hormone function

rasies concentration of calcium plasma by promoting Ca movement from bones, increasing Ca reabsorption from kidneys, and activating vitamin D

Ca movement from bones

PH promotes osteoclast activity, which is responsible for mobilizing bone Ca

osteoblast regulation of osteoclasts

osteoblasts secrete hormones, RANKL (+) and osteoproteogerin (-)

vitamin D function

stimulates reabsorption of Ca and HPO4 from the intestines

vitamin D synthesis

synthesized from cholesterol-derived pre-hormone in epidermal cells when skin is exposed to the sun. needs to be activated by the liver and then the kidney first

function of calcitonin

inhibits activity of bone osteoclasts when levels of calcium in plasma is too high