Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
87 Cards in this Set
- Front
- Back
|
classification of adenohypophyseal hormones
|
somato-lactogen group
two-subunit group proopiomelanocortin |
|
|
somato-lactogen group
|
prolactin/leuteotropin
growth hormone/somatotropin placental lactogen |
|
|
placental lactogen
|
not a pituitary hormone but structurally similar to PRL & GH
synthesized in placenta only during pregnancy |
|
|
two-subunit group
|
leuteinizing hormone
follicle stimulating hormone thyroid stimulating hormone |
|
|
proopiomelanocortin
|
large precursor protein broken down into ACTH
|
|
|
chemistry of GH
|
190 aas
20 kDA = effectively filtered by the kidneys 4 a-helices |
|
|
hypothalamic control of GH
|
mediated by regulation of cyclic-AMP at median eminence
GH-RH GH-RIH/somatostatin |
|
|
negative feedback regulation of GH
inhibition of GH-RH |
increased blood GH levels
IGF-I inhibits GH-RH and stimulated GH-RIH |
|
|
physiological down regulation of GH
|
glucose
stress |
|
|
physiological up regulation of GH
|
aas
exercise sleep ADH ghrelin ( secreted from gut after meal ) |
|
|
Transportation of GH in plasma
|
released in short bursts, bind to carrier protein to stabilize conc of GH according to equilibrium
only free GH is released from blood |
|
|
GH Mechanism of Action
|
1)direct effects on target tissues
2)indirect effects on target tissues |
|
|
GH direct effects on target tissues
|
stimulated target tissues synthesize and release IGF-I
liver-synthesized IGF-I acts on pituitary gland in negative feedback loop |
|
|
GH indirect effects on target tissues
|
via IGF-I produced by direct target tissues
ie. bone growth |
|
|
GH biochemical mechanism of action
|
GH binds two plasma membrane GH-receptors activing the JAK/STAT pathway
regulates expression of GH-specific genes |
|
|
biological actions of growth hormone
ie. What does Growth Hormone do to the body? |
effects on:
bone growth carbohydrate metabolism lipid metabolism protein metabolism mammary gland matabolism |
|
|
growth hormone effects on bone growth
|
classically mediated by IGF-I
|
|
|
growth hormone effects on protein metabolism
|
growth hormone promotes uptake and synthesis of proteins
"protein-sparing" effect increased protein = increased nitrogen content |
|
|
growth hormone effects on carbohydrate metabolism
|
glucose-sparing, antagonizing the use and uptake of glucose
|
|
|
growth hormone effect on lipid metabolism
|
releases lipid from adipocytes to be metabolized
|
|
|
growth hormone effects on mammary gland metabolism
|
auguments/stimulates lactation
indirectly mediated by IGF-I BST= recombinant bovine somatotropin given to dairy herds, controversial |
|
|
chemistry of prolactin
|
200 aas
22 kDa similar structure to GH, 4 a-helices |
|
|
placental prolactin
|
produced by placenta only during pregnancy
shuts down pituitary production of PRL |
|
|
pituitary synthesis of PRL
|
majority of synthesis of PRL
other sources are not significant contributors |
|
|
hypothalamic regulation of PRL
|
dopamine "prolactin release-inhibiting hormone"
thyrotropin-releasing hormone |
|
|
effect of dopamine on PRL production
|
"brake" or suppress
PRL in constant state of suppression via Prolactin Release-Inhibiting Hormone |
|
|
effect of thyrotropin-releasing hormone on PRL production
|
"accelerator" or simulator
|
|
|
feedback regulation of PRL
|
PRL inhibits synthesis
acting on hypothalamus and adenohypophysis |
|
|
physiological regulation of PRL
|
steroids
suckling response pregnancy |
|
|
effect of steroids on PRL production
|
estrogen stimulates pituitary synthesis & secretion considerably
|
|
|
effect of suckling response on PRL production
|
stimulates brain to increase prolactin levels
increases amount of food for baby and maintain breast function |
|
|
effect of pregnancy on PRL production
|
placental prolacting feedbacks to hypothalamus and adenohyphophysis to suppress pituitary prolactin production
|
|
|
transportion of PRL in blood
|
no carrier protein
low circulating levels in males, higher in females highest during pregnancy and lactation |
|
|
PRL mechanism of action
|
binds a pair of prolactin-receptors at plasma membrane, activating JAK/STAT pathways
increase in prolactin gene expression |
|
|
biological actions of prolactin
|
mammary growth and lactation
rodent corpus luteum male reproductive system |
|
|
effect of PRL on mammary growth and lactation
|
stimulate initiation of lactation
stimulate maintenance of lactation in some species |
|
|
effect of PRL on rodent corpus luteum
|
stimulates corpus luteum to produce progesterone
"luteotropic hormone" |
|
|
effect of PRL on male reproductive system
|
maintains accessory sex glands
|
|
|
effect of PRL in birds
|
maintains crop sac biology
crop: where crop milk is made |
|
|
effect of PRL in fish
|
high concentration of PRL-receptors in fish kdiney cell membranes
alters function of kidney when transitioning between fresh and salt water to adjust to new saltity |
|
|
placental lactogens
|
species specific
biological activities more similar to GH in some species and PRL in other species NOT a pituitary hormones; produced by placenta during pregnancy |
|
|
chemistry of thyroid stimulating hormone
|
a-subunit = 89aa
b-subunit = 112 aas 29 kDa glycoprotein 1% sialic acid |
|
|
hypothalamic control of TSH
|
thyrotropin-releasing hormone
somatostatin |
|
|
effect of thyrotropin-releasing hormone on thyroid stimulating hormone production
|
acts from hypothalamus on adenohypophysis to increase production and secretion of thyroid-stimulating hormone
(also stimulates PRL release) |
|
|
effect of somatostatin on thyroid stimulating hormone production
|
decreases TSH release from adenohypophysis
(also decreases GH release) |
|
|
feedback regulation of TSH
|
T3 & T4 act on hypothalamus to diminish TRH production, thus diminishing TSH production
|
|
|
physiological up regulation of TSH
|
cold stress
estrogens |
|
|
physiological down regulation of TSH
|
glucocorticoids
GH |
|
|
transportation of TSH in blood
|
NO carrier protein
half life = 75 min |
|
|
TSH mechanism of action
|
binds 1 plasma membrane receptor, activing G-protein, which activates adenylate cyclase
ATP converts it to cyclic-AMP, activing a protein kinase to modulate TSH gene expression |
|
|
biological effects of TSH
|
stimulate synthesis and secretion of thyroid hormones (multi-step process)
|
|
|
chemistry of FSH
|
a-subunit = 89 aas
b-subunit = 115 aas 29 kDa glycoprotein 5% sialic acid (longer 1/2 life) |
|
|
hypothalamic control of FSH
|
gondadotropin releasing hormone (GnRH)
|
|
|
effect of inhibin on FSH production
|
produced by gonadal tissues in both males and females for the purpose of reducing pituitary response to gonadotropin-releasing hormone
|
|
|
effect of estrogen on FSH production
|
in females, can stimulate or depress FSH secretion via hypothalamus
|
|
|
physiological regulation of FSH
|
closely regulated by neural input:
females: cyclic activity males: noncyclic activity |
|
|
transport of FSH in blood
|
NO carrier protein
half life = 3 - 4 hours |
|
|
FSH mechanism of action
|
bind and activate FSH-receptor, activating G-protein, stimulating ATP conversion of adenylate cyclase into cyclic-AMP, stimulating a protein kinase and gene transcriptions
|
|
|
biological effect of FSH
|
effects on ovary
effects on testis |
|
|
effect of FSH on ovaries
|
stimualate development of primary follicle
|
|
|
effect of FSH on testis
|
stimulate spermatogenesis and growth of the seminiferous tubules
stimulates production of angroden-binding protein from sertoli cells |
|
|
feedback regulation of FSH
|
inhibin
estrogen |
|
|
chemistry of luteinizing hormone
|
29 kDa
a-subunit = 89 aas b-subunit = 115 aas 1% sialic acid (shorter 1/2 life) |
|
|
hypothalamic control of LH
|
gonadotropin-releasing hormone (GnRH)
|
|
|
molecules which feedback regulate LH in males
|
testerone inhibits LH secretion
|
|
|
molecules which feedback regulate LH in females
|
during follicular phase:
estrogen stimulates LH secretion during luteal phase: estrogen and progesterone inhibit LH secretion |
|
|
physiological regulation of LH
|
neural inputs
(temp, light, environment, etc.) cyclic in females noncyclic in males |
|
|
transportation of LH in blood
|
no carrier protein
cyclic range in females can be an order of magnitude |
|
|
how does LH act on cell?
|
binds and activates LH-receptor, activing G protein, stimulating conversion of adenylate cyclase in cyclic-AMP by ATP, stimulating protein kinases, controlling gene transcription
|
|
|
effects of luteinizing hormone on ovary
|
1) corpus luteum development
2)progesterone synthesis and secretion by corpus luteum |
|
|
effects of luteinizing hormone on testis
|
stimulate testosterone synthesis and secretion
|
|
|
non-pituitary gonadotropins
|
pregnant mare serum gonadotropin
human chorionic gonadotropin |
|
|
proopiomelanocortin is a precursor for...
|
ACTH
MSH LPH |
|
|
chemistry of POMC
|
29 kDa
|
|
|
chemistry of ACTH
|
31 aas
|
|
|
chemistry of MSH
|
13 aas
cleaved in pars intermedia |
|
|
chemistry of Beta Lipotropin (LPH)
|
91 aas
|
|
|
hypothalamic regulation of POMC
|
corticotropin-releasing hormone (CRH)
melanocyte-stimulating hormone-releasing factor (MSH-RF) melanocyte-stimulating hormone release-inhibiting hormone |
|
|
feedback regulation of POMC
|
ACTH stimulates adrenal steroids
adrenal steroids feedback regulate hypothalamus to dec. CRH production adrenal steroids feedback regulate adenohypophysis to dec. ACTH production |
|
|
physiologic regulation of POMC
|
neural input
ie. stress, cold exposure, pain, emotion, diurnal cycle, hemorrhage, exercise, hypoglycemia, infection, trauma, toxins, etc. |
|
|
transport of ACTH in blood
|
no carrier protein
half life = 6-9 min therefore, released in bursts easily filtered by kidneys b/c so small |
|
|
ACTH mechanism of action
|
ACTH-bound receptor activates G protein, stimulating c-AMP,
activing side chain cleavage enzyme, converting cholesterol to pregnenolone |
|
|
MSH mechanism of action
|
MEESH-bound receptor activates G protein, activing c-AMP
activates side chain cleavage enzyme converts cholesterol to pregnenolone |
|
|
biological actions of POMC molecules
|
ACTH acts on adrenal gland
B-LPH acts on adipose tissue MSH acts on melanocytes |
|
|
effect of ACTH on adrenal gland
|
stimulates synthesis and secretion of glucocorticoids
glucocorticoids are at highest concentration around time of wakening and bottom out at 3-4 PM in nonnoctural species |
|
|
effects of beta lipotropin hormone on adipose tissues
|
stimulates lipolysis from triglycerides
|
|
|
effect of MSH on melanocytes
|
stimulates melanocytes in skin to synthesis and secrete pigment
|
