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54 Cards in this Set
- Front
- Back
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what produces growth hormone
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somatotropes in the anterior pituitary in response to GHRH
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where does GHRH come from
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the cell bodies in the hypothalamus
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what receptors are similar to GH
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prolactin
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what is the steps in which GH is secreted
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hypothalamus secretes GHRH which acts on the anterior pituitary
the anterior pituitary releases GH which acts on the liver the liver produces IGF-1 which goes to all the tissues that need to grow |
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how does IGF-1 regulate GH secretions
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IGF-1 binds to somatotropes (anterior pituitary) supressing further release of GH
IGF-1 goes to hypothalamus stimulating somatostatin which inhibits GH release from the anterior pituitary |
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how does ghrelin control GH secretion
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positively stimulates production and secretion of GH from anterior pituitary
acts on the hypothalamus stimulating the secretiong of GHRH |
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when is ghrelin made
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in response to stimuli (food)
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how does GH control GH secretion
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by working on the hypothalamus and inhibiting the secretion of GHRH
GH also works on the anterior pituitary suppressing its own production |
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how does GHRH control GH secretion
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GHRH is secreted from the hypothalamus and acts on the anterior pituitary (binds to somatotropes) causing it to secrete GH
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what are all the negative regulators of the GH secretion
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IGF-1
GH Somatostatin Beta-adrenoceptor agonist |
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what are all the positive regulators of GH secretion
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ghrelin
GHRH alpha-adrenoceptor agonists 5-HT |
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what carries out all the activities of GH
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IGF-1
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how does dopamine PASSIVELY regulate GH secretion
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by increasing the GHRH production
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what are the stimuli for GH release that are used for diagnosis
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arginine
glucagon insulin induced hypoglycemia GH secretion in response to GHRH |
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what kind of hormone is glucagon
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pancreatic
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what is insulin induced hypoglycemia
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treat patient with insulin to cause hypoglycemia and hypoglycemia induces GH release
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what is the preferred test by the GH research society
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insulin induced hypoglycemia
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what are some of the GH activities carried out by IGF-1
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growth in open epiphyses (bone growth plates) - IGF-1 causes bone growth in open bone plates
muscle proliferation (myoblast proliferation/differentiation stimulates protein synthesis) |
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what increases GHRH production
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dopamine
ghrelin |
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why are other provocative stimuli for GH release used
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because GH spikes occur early in the morning/night and it is inconvienient to keep the patient over night to get those results
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what closes the bone plates
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estrogen
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what is the principle mediator of GH activity
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IGF1/IGF2
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what was done to see how IGF effected GH function
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mutation analysis (took out mice IGF-1 gene and gave them GH and nothing happened)
change IGF receptor (w/o IGF receptor no growth can occur) |
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how is the IGF receptor composed
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2alpha chains
2beta chains extracellular and intracellular domain (intracellular domain has a tyrosine kinase attached) |
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how does GH circulate in the blood and how does IGF circulate in the blood
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GH circulates in blood unbound to protein
IGF is protein bound in blood BEING PROTEIN BOUND EXTENDS YOUR HALF LIFE |
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what are the effects of GH as children grow
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increase AA uptake in tissue
stimulates increase in transcription/translation decrease protein catabolism (want to use protein instead of excrete it) increase cell division |
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how do GH effect lipids
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GH directly cause lipolysis (liberation of FFA from adipose tissue)
GH blocks lipid storage/uptake FFA will be converted by the liver to acetyl CoA to be used as fuel |
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how do GH effect carbohydrates
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GH reduces uptake of GH into the muscles (keep glucose in the blood, because some organs (heart/brain) prefer using glucose for energy instead of fat (acteyl CoA)
GH increases insulin GH increases gluconeogenesis in the liver (make glucose using FFA) |
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why is GH called a diabetogenic hormone
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b/c it makes it look like you have diabetes due to high glucose in blood and high insulin as well
you appear INSULIN RESISTANCE AND MAY HAVE GLUCOSE IN URINE |
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what are the GH levels in children vs adults
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high GH levels in kids
decrease in GH production in adults GH released in pulses |
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what is dwarfism
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due to GH defect (GHRH, GH, GH receptor, IGF, IGF receptor) long bones don't grow therefore has short stature
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what are some of the defects that cause dwarfism
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hypothalmic
pituitary gland peripheral defect |
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what causes a hypothalmic defect and how is it treated
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don't make GHRH
treat by giving GH or GHRH |
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what causes pituitary gland defect and how is it treated
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don't make GH in reasponse to GHRH eventhough have enough GHRH
treat by giving GH |
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what causes a peripheral defect and how is it treated
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defect in GH receptor, IGF production, or IGF receptor
if defect in IGF1 production, you are making GH but you have functional GH receptor tehrefore won't make IGF. TREAT BY GIVING IGF if defect in IGF receptor, NO TREATMENT |
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what occurs in Adult GH deficiency
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unhealthy fat distribution (buffalo hump/fat stomach)
loss of muscle mass (due to GH is needed for myoblast proliferation and w/o it there will be no myoblast proliferation which is needed to protein synthesis) |
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what are may result as due to Adult GH deficiency
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if not addressed increased mortality to cardiovascular disease (due to the increased deposition of lipids, GH STIMULATES LIPOLYSIS AND USE OF LIPIDS AS FUEL)
impairment of psychosocial function |
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what is seen in adults with excess GH
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increase glucose in blood (due to gluconeogenesis in liver)
increase lipid in blood (due to lypolisis of adipose tissue) increase insulin |
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how does GIANTISM OCCUR
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occurs due to GH excess before bone growth plates close
bones will continue to grow |
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what occurs in ACROMEGALLY
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GH excess after bone growth plates have closed
soft bones thicken (brow, jaw, knuckles, digit bones) these people will have a different appearance |
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what will be seen in a blood sample from people who have Acromegally and Giantism
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elevated GH and IGF
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what will increase prolactin plasma levels
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hypoglycemia
Thyrotropin releasing hormone (TRH) |
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where is the prolactin receptor found and how can it be stimulated
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found in ovaries, testes, prostate, liver, mammary gland, t cells
prolactin receptor is similar to GH receptor and YOU CAN USE GH TO ACTIVATE THE PROLACTIN RECEPTOR |
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what is the function of prolactin
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important in development of ductal lobuloalveolar epithelium in mammary gland (responsible for making milk)
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what occurs in milk production
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prolactin is secreted in the anterior pituitary by LACTOTROPES
prolactin is secreted in response to suckling *suckling induces expression of casseins (milk proteins) |
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how is prolactin secretion regulated
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dopamine is the brake that prevents prolactin release
dopamine regulates prolactin via negative control |
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what is the prolactin inhibitory factor
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dopamine
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what is another name for dopamine
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prolactin inhibitory factor
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what is hyperprolactinemia
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too much prolactin in the blood
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what happens to women w/ hyperprolactinemia
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amenorhea (no period) and infertility in women
galactorhea (produce milk w/o baby) loss of lobido |
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what happens to men w/ hyperprolactinemia
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impotence and infertility
loss of lobido |
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what are the causes of hyperprolactinemia
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pituitary tumors
disease that interfers w/ dopamine hypothyroidism treatment w/ dopamin ANTAGONIST |
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how is hyperprolactinemia treated
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dopamine AGONISTS
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how does prolactin prepare the breast for lactation
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it works with estrogen and progesterone
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