endocrine system Flashcards
endocrine
targets a distant cell throughout bloodstream
exocrine
secretes enzymes into ducts
paracrine
targets nearby cell
autocrine
targets itself
peptide hormones
bind to surface cell membrane receptor –> receptors start cell signaling pathways via secondary messengers
steroids
diffuse plasma membrane and bind receptor in cytoplasm –> hormone + receptor is transported into nucleus to act transcriptionally
tyrosine derivatives
thyroid hormones : lipid-solube, bind to receptors in nucleus, and require protein carrier in blood
catecholamines: water-soluble, bind receptors on target tissue, and mainly act via secondary messenger cAMP
secondary messengers
- small molecules that pass along signals
- initiated by ligand-receptor binding
- amplify signal strength to target molecules in the cytoplasm or nucleus
examples: IP3, cAMP, calcium, DAG
hypothalamus
- secretes releasing hormones to anterior pituitary gland
- APG responds by secreting hormones
- hypothalamus secretes ADH and oxytocin to be stored in the posterior pituitary gland
- PPG stores ADH and oxytocin for release
ADH ——> kidneys
oxytocin ——> uterus/mammary gland
ACTH
stimulates adrenal cortex –> releases glucocorticoids
TSH
stimulates thyroid gland to release thyroid hormones
LH
- stimulates corpus luteum formation in girls
- stimulates interstitial cells of tests to produce testosterone
FSH
in women: stimulates maturation of ovarian follicles to secrete estrogen
in men: stimulates seminiferous tubule maturation and sperm production
hGH (somatropin)
stimulates bone and muscle growth
prolactin
stimulates milk production