Endo 3

Front 1

Somatotroph cells located in

Back 1

Anterior pituitary

Front 2

Somatotrotoph characteristics

Back 2

Have numerous large secretory granules 350 to 500 nm in diameter
• 40% to 50% of cells
• hGH makes up 8 to 16% of dry weight of pituitary (4-8 mg/gland)

Front 3

GH structure characteristics

Back 3

Synthesized as a larger form (proGH) then processed
• 191 amino acids (MW = 22,650)
No carbohydrate
• Two intramolecular disulfide bonds
• Sequence homology to human placental lactogen (hPL also called human chorionic somatomammotropin - hCS), human prolactin, and placental GH variant

Front 4

Human GH works in

Back 4

humans and lower species
• Only human and non-human primate GH active in humans

Front 5

GH receptor characteristics

Back 5

MW about 130 kD
Heavily glycosylated

Front 6

GH receptor is a member of

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of the cytokine receptor superfamily which includes the prolactin receptor
• Acts through JAK2 and then STAT 1, 3, and 5 or other intermediates

Front 7

Gh plasma levels are really low, so it makes it hard to

Back 7

detect it on the blood. Also it's half life is very short, so it is easily cleared out of the system.

Front 8

The plasma binding protein for GH is

Back 8

the extracellular (hormone binding) domain of the GH receptor.
• Plasma half life 6 to 20 min

Front 9

Gh higher in puberty but

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it is all throughout life. Gh is not only involved in growth is has other roles

Front 10

Meals effect in plasma levels of gh

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Levels show 1 or 2 sharp increases 3 to 4 h after meals

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Fasting ( hypoglycemia) greater than 1day associated with

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Increased gh levels

Front 12

Sleep causes in gh plasma levels

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increase 1 hr after onset of sleep.
Associated with Stage III and IV sleep
– Inhibited by REM sleep

Front 13

GH plasma levels related to age

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Levels higher at birth but fall by 2 weeks
– GH levels maintained in the elderly although at a slightly lower level

Front 14

Exercise effect on GH

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increases plasma levels

Front 15

GH sex differences

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Female levels slightly higher than males and have greater response to exercise, hypoglycemia and arginine

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Corticosteroid excess impairs responsiveness to

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hypoglycemia and the sleep related peak

Front 17

Meals increases concentration of

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aa like arginine in plasma

Front 18

Growth Hormone releasing hormone action is mediated by

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cAMP and Ca2+

Front 19

Ghrelin characterisitcs

Back 19

Preprohormone converted to 28-amino acid peptide
– Produced in the stomach and hypothalamic arcuate nucleus
– Acts through growth hormone secretagogue receptor
– Also functions to increase hunger
• Acts on hypothalamic feeding centers

Front 20

Somatostatin (growth hormone release inhibiting hormone) characteristics

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14 amino acids long
– Predominantly in anterior periventricular region of hypothalamus
– Also found in the delta cells of the pancreas and gut
– Also inhibits release of TSH, glucagon, insulin, and GI tract hormones

Front 21

IGF-1 characteristics

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Inhibits GH release from the pituitary
– Stimulates somatostatin release from hypothalamus

Front 22

PHYSIOLOGICAL EFFECTS OF GH

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Gh would act to increase plasma glucose.

Front 23

Removal of GH will cause

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Less lean body mass
– Increase in % body fat
– Decrease in skeletal growth in juvenile

Front 24

GH administration leads to

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Increases growth of heart, pancreas, liver and kidneys
– Increases relative volume of body fluids
– Causes positive nitrogen balance

Front 25

Gh specific effects regarding proteins and its constituents

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Increases amino acid transport
– Increases ribosome number
– Increases mRNA
– Increases levels of enzymes used in protein synthesis

Front 26

Gh specific effects regarding fat

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GH increases mobilization from adipose tissue

Front 27

Gh specific effects regarding glucose

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GH indirectly increases plasma glucose levels – Inhibits muscle uptake of carbohydrate

Front 28

Somatomedins's job is basically

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mediate the function of gh.

Front 29

IGF-I is the same as

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somatomedin C, basic somatomedin, NSILA-1

Front 30

IGF-II is the same as

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MSA, NSILA-II

Front 31

IGF-I has 70 amino acids and MW of

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7,650.

Front 32

GF-II has 67 amino acids and MW of

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7,470.

Front 33

IGFI homology to IGFII and insulin

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60% to IGF2
50% to insulin

Front 34

IGI is produced in the liver in response to

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to GH (mainly IGF-I).
• Some produced by many other tissues.

Front 35

IGF can be used to know if someone has taken GH because

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ong half life, it can be used to measure if a person is taken gh
HalflifeIGF2to4h

Front 36

Almost all igf in plasma is bound by

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IGF binding protein, binding which is noncovalent

Front 37

The most abundant IGF type in blood is

Back 37

IGF3
150,000 MW
– Composed of acid labile 88 kD subunit and acid stable glycosylated 40 to 46 kD (protein 28.5 kD) binding subunit
• GH increases levels
• Binds IGF-I and II the same

Front 38

IGFBP1 is

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Non-GH dependent binding protein
Non-GH dependent binding protein

Front 39

IGFBP1 binds better to

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IGFI than II

Front 40

IGFBP2 is found in

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Found in fetal serum
• Binds IGF-II better than IGF-I

Front 41

Possible Functions of IGFBPs

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Transport IGFs and control movement from vascular space
• Prolong IGFs half-life and regulate metabolic clearance
• Provide a means of tissue- and cell type- specific localization
• Directly modulate interaction of IGFs with their receptors