Endocrine System Flashcards
endocrine system
made of organs which secrete hormones into blood
hormone
a chemical messenger transported to target cells, where it binds to specific hormone receptors
what increases a hormone’s effect
larger amount binding
hormone characteristics
- stability- larger/more complex=more stable
- communication- interaction w/ specific target tissue
- distribution- binding proteins help the hormones travel thru blood to target tissue
steroid hormone
lipid soluble +nonpolar (diffuse thru membrane), chem structure originates from cholesterol, secreted by adrenal, ovary, testes, placenta
examples of steroid
enzymes, structural proteins for growth/repair, regulatory proteins that alter enzyme function
non steroid hormone
non lipid-soluble, polar (can’t diffuse), travel in blood to targets, 2000-10000 receptors per cell
examples of nonsteroid
adenylate cyclase (produces cyclic amp, activates protein kinase)
acute hormone secretion
concentration changes suddenly/irregularly, water soluble/nonsteroid hormones (ex: epinephrine due to stress)
chronic hormone secretion
maintenance of constant hormone concentration, lipid soluble/steroid hormones (ex: thyroid hormones)
episodic hormone secretion
secreted at predictable intervals and concentrations, lipid soluble/ steroid hormones (ex: menstruation)
what are the 3 methods most hormones are controlled by?
- humoral
- neural
- hormonal
humoral control
action of a substance other than a hormone on an endocrine gland
neural control
control by nervous system (ex: stress stimulates the adrenal gland)
up regulation
increase in number of cell receptors, more hormones become available and activity becomes easier
hormonal control
control of one gland by hormones of another (ex: inhibiting hormones)
down regulation
the desensitization of a cell to the effects of a hormone, decreases the number of receptors and decreases hormone’s effect
how is the posterior pituitary regulated?
the hypothalamus uses a specialized neural pathway- cell bodies of neurons of the hyp. extend to the post. pit.
how is the anterior pituitary regulated?
thru specialized blood vessels- portal system of capillary networks connects the hypothalamus to the ant. pit., neurohormones release or inhibit hormones
hormones of the posterior pituitary
Antidiuretic hormone (ADH) and Oxytocin
Antidiuretic hormone
- reduces water loss to maintain plasma volume
- stimulated by high plasma osmolality and low plasma volume due to sweating
plasma osmolality
increased concentration of dissolved substances (electrolytes)
oxytocin
(post pit) reproductive hormone which induces labor by stimulating uterine contraction, causes milk expulsion, cramps, unclear function in men
hormones of the anterior pituitary
(post pit) growth hormone, prolactin, thyroid stimulating, adrenocorticotropic, LH + FSH
Growth hormone
(ant pit)
anabolic (bone/muscle growth), stimulates lipolysis, levels elevated during exercise, regulates blood levels of nutrients after exercise/during fasting
prolactin
(ant pit) primary role= milk production, enhances progesterone secretion by ovaries, regulated by prolactin inhibiting/releasing hormones
thyroid stimulating hormone (TSH)
(ant pit) increases phospholipase activity, opens Ca2+ channels and increases concentration of CA2+ in thyroid gland, release of TSH causes secretion of T3 and T4
Adrenocorticotropic (ACTH)
(ant pit) causes cortisol and aldosterone release from adrenal cortex, increases melanin production, derived from same molecule as MSH, endorphins, and lipotropins
hormones of the thyroid
T3, T4, Calcitonin, parathyroid hormone
LH and FSH
(ant pit) stimulated by GnRH from hypothalamus, gonadotropins promote growth and function of gonads, regulate production of gametes/reproductive hormones
T3 and T4
(thyroid) controlled by release of TSH, stimulated by exercise. Low levels lead to obesity: increase fatty acid oxidation, enhances glycolysis
calcitonin
(thyroid) regulates plasma Ca2+, promotes bone strength in kids
Parathyroid hormone
plasma Ca2+ regulation in bone, kidneys, small intestine, Ca2+ reabsorption in kidneys so less Ca2+ leaves the body in urine
adrenal medulla
inner portion of adrenal gland, modified SNS ganglion
adrenal cortex
outer portion of adrenal gland, secretes steroid hormones
catecholamines
epinephrine +norepinephrine, prepare the body for fight/flight, increase HR, BP, respiration, decrease kidney/digestive function
alpha and beta receptors
both combine with the catecholamines, alpha opens ca2+ channels, beta opens cyclic amp channels
adrenal medulla hormones
epinephrine+ norepinephrine
adrenal cortex hormones
mineral corticoids, gonadicocorticoids, glucocorticoids
mineralocorticoids
(adrenal cortex) regulate Ka and Na balance in blood, increase Na absorption by kidneys, eventually increases bp
gonadicocorticoids
(adrenal cortex) androgen hormones that lead to development of male secondary sex characteristics , mostly secreted by reproductive system
glucocorticoids
stimulated by exercise/fasting, promotes lipid breakdown, reduces glucose uptake, stimulates gluconeogensis, reduces intensity of inflammatory response
hormones of the pancreas
insulin and glucagon
pancreas
both exocrine (produces pancreatic juice) and endocrine (islets of langerhans secrete alpha cells- glucagon, beta cells-insulin, and delta cells- somatostatin)
insulin
(B cells of pancreas) secreted during hyperglycemia, promotes glucose uptake into cells, reduces circulating glucose
glucagon
(alpha cells of pancreas) opposite function of insulin: secreted during hypoglycemia, promotes glycogenolysis in liver, mobilizes fatty acids, increases circulating glucose
factors that increase insulin secretion
hyperglycemia, parasympathetic stimulation with food intake, GI hormones that regulate digestion (gastrin, secretine, cholecystokinin)
factors that decrease insulin secretion
hypoglycemia, activation of SNS, somatostatin (released during food intake), glucagon regulation (increased BG inhibits, decreased BG stimulates)
testosterone
(testes) anabolic properties, androgenic properties
inhibin
released by ovaries and testes, increases FSH secretion from the anterior pituitary
estrogen and progesterone
secreted by the ovaries, repairs mammary glands, leads to fatty tissue buildup
Erythropoietin
released by kidney, increases O2 carrying capacity of red blood cells
