endocrine 3 Flashcards
___ pituitary secretes 7 hormones, synthesis and release of each of the 7 is under control of…
anterior
1 of 7 releasing factors synthesized in hypothalamus
the ___ is where all the releasing factors from hypothalamus are released into
median eminence
the anterior lobe of pituitary contains ___ cells, so it is called ___
classical endocrine secretory cells (no neuro)
endohypophysis (pars distalis)
what is a unique feature of anterior pituitary structure with hypothalamus?
they are directly connected by set of modified blood vessels called the portal vessels/system –>special set of capillaries at bottom of hypothalamus that are the receiving point for all the receiving factors, they are dumped right into the capillaries –> the capillaries do not have the typical blood-brain barrier b/w CSF and blood, so very permeable, which allows releasing factors to diffuse right into blood –> capillary beds then form a portal vein, goes down hypothalamic hypophysial –> 2nd cap bed, releases all releasing factors
releasing factors can be synthesized and secreted in very…
small concentrations –> directly transported from hypothalamus to anterior pituitary where they have their effect –> then released into general circulatory system & diluted below their effective concentrations, effects are stopped
how are the circulations between anterior & posterior pituitary related?
completely separate - 2 separate capillary beds & circulations
hypothalamus produces 7 releasing factors & dumps into median eminence, what are their classifications?
6 peptides & 1 amine
4 stimulatory peptides
3 inhibitory (2 peptides & 1 amine)
what are the 2 major cell types in anterior pituitary?
acidophils - stain orange/red in response to dyes, acid-loving (secrete GH & prolactin)
basophils - stain blue with basic dyes, secrete ACTH, TSH, MSH, LH & FSH
how are glucocorticoids regulated? give example
by negative feedback short & long loops
endocrine gland A is hypothalamus, target tissue B is anterior pituitary –> endocrine gland A’s signal/hormone is 1 of the 7 releasing factors –> hits target tissue B(anterior pituitary) when then releases one of the 7 hormones –> downstream target of anterior pituitary is one of the 7 targets that the hormone effects
short loop: hormone from pituitary goes back to hypothalamus and shuts off releasing factor
long loop: hormone from other gland in body goes to hypothalamus and shuts off releasing factor
what is the precursor of glucocorticoids? and name a few
steroid hormones all derived from cholesterol
3 major glucocorticoids: cortisol, cortisone, corticosterone - helps regulate glucose metabolism in the body
what is the signal for production of glucocorticoids?
long-term stress or starvation (long-term depletion of carbohydrate stores)
describe the feedback loop and the RF & hormones involved in making glucocorticoids
glucose is primary metabolic fuel and is readily available from glycogen…when glycogen levels are depleted, have to call on alternate sources for glucose
signal of starvation/stress received by hypothalamus –> synthesizes & secretes releasing factor CRH –> CRH released to portal system and travels to anterior pituitary where it has stimulatory effect and causes synthesis & release of ACTH (tropic hormone- effects another gland) –> ACTH target tissue is adrenal cortex –> stimulatory, synthesis & secretion of glucocorticoids –> ACTH also feeds back to hypothalamus and cuts off production of CRH (short feedback loop) –> glucocorticoids have multiple target tissues, also circulate & feed back to hypothalamus to cut production of CRH (long feedback loop)
glucocorticoids are steroids so…
they dissolve thru target tissue membrane and bind to receptor in cytoplasm & form glucocorticoid-receptor complex –> migrates to nucleus and binds to glucocorticoid-receptor elements (GREs), can be positive and active a gene or can be negative and turn off gene
what is glucocorticoids major function in regulating glucose production?
they active enzymes that will synthesize glucose from non-carbohydrate sources
keep your body running thru other metabolic sources of fuel
what is the first non-carbohydrate source that glucocorticoids help produce?
lipids/fats – convert fats to glucose & ATP
glucocorticoids upregulate genes that result in production of enzymes, lipases –> lipases act on lipids, resulting in glycerol & phospholipids –> they run thru metabolic pathways to continue making ATP thru TCA cycle –> glycerol can be used to also make more glucose
