lec 6

endocrine

ductless glands that secrete hormones into the blood

exocrine

secrete product into ducts which go into lumen of another organ

three classes of hormones

amine, peptides, and steroids

amines structure, receptor, how it travels in blood, and examples

derived from tyrosine, plasma membrane, diffuses freely, ex. epi and noepi, dopamine, TH

peptides structure, receptor, how it travels in blood, and examples

string of AAs, plasma membrane, diffuses freely, ex. insulin, glucagon

steroids structure, receptor, how it travels in blood, and examples

derived from cholesterol, can enter cell membrane/intracellular, needs a binding protein, ex. testosterone, estrogen, cortisol, and aldosterone

3 types of input hormone secretion is controlled by

changes in plasma concentration of ion/nutrients, neurotransmitters released, other hormones

pituitary gland (hypophysis)

lies at the base of hypothalamus in brain

anterior pituitary gland

connected to hypothalamus via portal system, 2/3 gland

difference between anterior and posterior pit gland

ant synthesizes, stores and secretes hormones while the posterior glands have hormones synthesized by hypothalamus and then it stores and secretes them

ant pit gland is inhibited and stimulated by?

hypothalamus hormones

six hormones secreted by anterior pit gland

FSH, LH, TSH, GH, Prolactin, ACTH

what hypothalamus hormone stimulates FSH and LH

GnRH

what hypothalamus hormone stimulates/inhibits GH

GhRH stims GH and SST (somatostatin) inhibits GH

what hypothalamus hormone stimulates TSH

TRH

what hypothalamus hormone inhibts Pro

DA (dopamine)

what hypothalamus hormone stimulates ACTH

CRH (corticotropin release hormone)

posterior pit gland

connected to hypothalamus thru neurons, 1/3 of gland

post pit gland hormones

oxytocin, ADH (vassopressin)

what does ADH (anti diuretic hormone) do

water retention, and has 2ndary effect (high BP)

what are the two TH

T3 (triiodothyronine) and T4 (thyroxine)

TH actions

control how every cell and organ in your body uses energy and manages → metabolism, body temp, growth and development

permissive effects of TH

TH allow another hormones to do its job better ex. epi/norepi receptors and GH

TH is necessary for?

proper growth and development

negative feedback - when there’s enough T3 and T4

T3/T4 shuts down TSH activity (inc TH and dec TSH)

negative feedback - when there’s low T3 and T4

T3/T4 increases TSH activity (dec TH and inc TSH)

hypothyroidism

decreased TH, increased TSH

hypothyroidism sequence

decrease in iodine → thyroid fails and cant make TH → released hypothalamus/AP gland from negative feedback inhibition → increase in TRH → increase in TSH to force thyroid to work harder

what causes hypothyroidism

Hashimotos thyroiditis

hypothyroidism symptoms

cold intolerance, weight gain, fatigue, depression

hyperthyroidism

increased TH, decreased TSH (strong neg feedback on TSH)

what causes hyperthyroidism

Graves disease - the production of antibodies mimicking TSH bind and activate TSH receptors in thy gland → chronic stimulation of thy gland

hyperthyroidism symptoms

heat intolerance, weight loss, protein catabolism, weakness, fatigue, increased appetite, tremors, signs of sympathetic drive