endocrine system Flashcards
Peptide hormones
derived from large polypeptides, charged and can’t pass through plasma membrane, so bind extracellular receptor; hormone is first messenger and triggers second messenger transmission (cAMP, IP3, and DAG); activates a G protein coupled receptor; has rapid for short lived response, quick to turn on response
steroid hormones
derived from cholesterol, can easily cross membrane-intracellular receptors; upon binding, steroid-receptor complex undergo conformational change that allows to bind to dna and change transcription; slower response but longer lived; not water-soluble, must be carried by proteins (albumin)
amino acid derived hormones
derived from one or two amino acids; includes catecholamines such as E and NE
direct hormones
secreted and act directly on target tissue
tropic hormones
require an intermediary to act; ex. when a hormone stimulates production of another hormone which then acts on target tissue
hypophyseal portal system
hypothalamus exerts control on anterior pituitary through paracrine release of hormones into portal system that connects the two
hypothalamus-posterior pituitary interaction
neurons in hypothalamus sends axons directly to posterior pituitary, which can release oxytocin and vasopressin (antidiuretic hormone-ADH)
prolactin
released by anterior pituitary, stimulates milk production; dopamine release from hypothalamus decreases its secretion
endorphins
decrease perception of pain; direct hormone released from anterior pituitary
growth hormone
direct hormone released from anterior pituitary; promotes growth of bone and muscle, which requires lots of glucose; prevents glucose uptake in certain tissues that are not growing to allow muscle and bone to use it; GH release stimulated by GHRH from hypothal.
ADH/AVP
secreted from posterior pituitary in response to low blood volume or increased blood osmolarity; increases permeability of collecting duct to water, which leads to greater reabsorption or water from nephron; leads to increased blood pressure
oxytocin
released during childbirth, allows for contraction of uterus; also stimulated by suckling since it promotes milk ejection; positive feedback loop:oxy release leads to greater contractions which leads to more oxy release
TSH
released from pituitary in response to TRH from hypothal.; stimulates thyroid to release T3 and T4
Thyroid hormones
triiodothyronine (T3) and thyroxine (T4); have 3 and 4 iodine atoms respectively; increased amounts lead to increased cellular respiration, stimulatate metabolic activity; negative feedback leads to decreased TRH and TSH
hypothyroidism
insufficient amounts of thyroid hormones as result of iodine deficiency or inflamed thyroid gland; causes decreased body temp, slowed respiratory and heart rate, and weight gain
hyperthyroidism
excess of thyroid hormone, may result from tumor or thyroid overstimulation; can cause heightened activity, increased body temp, increased respiratory and heart rate, weight loss
calcitonin
acts to decrease plasma calcium; increases calcium excretion from kidneys, decreased calcium reabsorption from gut, increased storage of calcium in bone
parathyroid hormone (PTH)
raises blood calcium levels by decreasing excretion through kidneys, increasing reabsorption from gut, and breaking down bone to free up Ca; activates Vitamin D-increased absorption from gut
glucocorticoids
secreted from adrenal cortex; steroid hormones, such as cortisol; stress hormones that increased blood glucose; under control of CRF and ACTH
aldosterone
secreted by adrenal cortex; increased sodium reabsorption in convoluted tubule and collecting duct, which increases water reabsorption; increases blood pressure, but does not change plasma osmolarity
adrenal medulla
releases catecholamines, NE and E to activate sympathetic nervous system; increases glycogenolysis (breakdown of glycogen), increases heart rate, dilates bronchi, alters blood flow to supply skeletal muscle, heart, lungs, and brain needed for response to stressor; short-term fast stress response
pancreas
has exocrine and endocrine functions; has islets of Langerhans- groups of hormone-producing cells- contain either alpha, beta, or delta cells, which each produce different hormone
glucagon
secreted when fasting as result of low glucose in blood; stimulates degradation of protein and fat, conversion of glycogen to glucose in order to increase glucose levels
insulin
secreted when blood glucose levels are high, after a meal; induces muscle and liver cells to take up glucose and store as glycogen, stimulates anabolic processes
hypoglycemia
too much insulin will result in low blood glucose levels
hyperglycermia
insufficient insulin or insensitivity to insulin results in high blood glucose and leads to diabetes mellitus; causes excessive glucose in kidney (because too much in blood for it to reabsorb), leading to increased excretion of water
somatostatin
released by hypothalamus; inhibitor of insulin and glucagon secretion; stimulated by high blood glucose and amino acid concentrations; also inhibits growth hormone secretion
melatonin
secreted by pineal gland; involved in maintaining circadian rhythms; responds to decreased light from retina
erythropoietin
stimulates bone marrow to produce red blood cells in response to decreased oxygen levels
atrial natriuretic peptide (ANP)
in response to excess blood volume, promotes excretion of sodium, which increases urine volume
substance P
involved with perception of pain
