Term
| Where does somatotropin (GH) originate? What its role in young animals vs adults? |
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Definition
-originates from anterior pituitary
-promotes tissue & body growth in young animals
-regulates lipid & protein metabolism in adults |
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Term
| Which hormones stimulate growth during fetal life? |
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Definition
IGF1 & IGF2
(Insulin-like Growth Factors) |
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Term
True or False
Growth hormones are not species specific, so it is common to use animal-sourced GH in humans with growth deficiencies |
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Definition
False
The protein sequence of GH is different between species, not compatible |
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Term
| Which hypothalamic neurohormones stimlate/inhibit GH? |
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Definition
stimulate: GHRH
inhibit: GHIH |
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Term
| How does GH regulate growth? |
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Definition
-stimulates production of IGF1 in liver
-IGF1 then stimulates cartilage & bone growth, milk production |
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Term
| Which type of receptor does GH use? |
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Definition
| cytokine (interleukin) family |
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Term
| How is GH secretion regulated? What might increase secetion? (4) What inhibits secretion? (1) |
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Definition
-hypothalamus receives info from external stimuli & nutrients in blood
-increases during sleep (circadian rhythm)
-high AA low glucose in blood will increase GH secretion
-exercise & stress increase GH secretion
-sex hormones increase GH secretion (growth spurt at puberty)
-IGF1 causes negative feedback on GH secretion |
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Term
| Describe the direct effects of Growth Hormone (4) |
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Definition
Anabolic: promotes protein synthesis
Catabolic: stimulates lipolyses & reduces lipogenesis
-lipolysis increase production of FA's
-also decreases glucose use in most tissues, increasing blood [glucose] |
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Term
| Describe the indirect role of GH via IGFs (4) |
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Definition
-stimulates synthesis of IGF1 & its binding proteins in liver
-IGF1 stimulates proliferation of cartilage cells (chondrocytes) increasing bone growth
-stimulates satellite cells (muscle fibre growth)
-stimulates AA uptake & protein synthesis |
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Term
| Describe the structure of IGF1 & what type of receptor it uses |
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Definition
-polypeptide chain, usually bound to carrier proteins
-acts via its one tyrosine kinase receptors |
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Term
| Which has a longer half-life, GH or IGF1? |
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Definition
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Term
True or False
GH plays a major role in mammary gland development |
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Definition
false
It is involved with milk production, but not the growth of epithelial/secretory cells |
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Term
| Describe the effects GH has on lactation |
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Definition
| GH directs nutrients towards mammary gland for milk production rather than allow insulin divert them to lipogenesis for storage |
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Term
| Why would bovine GH be used in milking cows? What is the human concern? |
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Definition
-can increase milk production 10% in early lactation, 40% in late lactation
Concern: bovine & human IGF1 have similar sequences, infants can absorb GH & IGF in the gut, this would alter their growth/development |
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Term
| Describe some of the pathologies associated with GH |
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Definition
Overproduction of GH
-causes gigantism if it occurs before puberty
-causes acromegaly, increased bone width & density, diabetes after puberty
Lack of GH Production
-causes dwarfism
-mainly due to defects of GH or the GH receptor genes |
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Term
True or False
Dwarfism due to genetic defects of the genes responsible for GH production & GH receptors is an untreatable disease |
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Definition
False
Injections of recombinant GH and IGF1 can treat the issue |
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Term
| Is the pancreas an endocrine or exocrine gland? |
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Definition
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Term
| What is the term for the endocrine regions of the pancreas? |
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Definition
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Term
| What types of cells are found in the islets of Langerhans and what do they secrete? |
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Definition
beta cells: secrete insulin
alpha cells: secrete glucagon |
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Term
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Definition
| the initial product of translation, will need to undergo processing to be converted to a functional hormone |
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Term
| Describe the synthesis & secretion of insulin |
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Definition
-produced as preprohormone, converted to insulin by removing a connecting (C)-peptide
-secreted, circulates free and is then degraded in target cells or in liver |
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Term
| Describe the synthesis & secretion of glucagon |
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Definition
-29AA peptide produce as a preoprohormone which is converted to glucagon
-secreted, circulates free and is then metabolized in liver & kidneys |
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Term
| Describe the actions of insulin (3) |
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Definition
-upregulates membrane glucose transporters, stimulating cellular uptake of glucose
-stimulates storage of glucose as glycogen in liver & muscle, TG's in adipose tissue
-stimulates AA uptake
Overall effects: decrease blood glucose & AA levels |
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Term
| What is the major anabolic hormone of the body |
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Definition
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Term
| Describe the actions of glucagon (3) |
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Definition
-activates the enzyme responsible for glyocogenolysis in liver, triggering release of glucose
-stimulates gluconeogenesis in liver
-stimulates release of FAs from TGs in adipose tissue |
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Term
| What regulates the release of insulin & glucagon? (4 points) |
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Definition
-primarily the concentration of glucose in blood
-AA concentration in blood to a small extent
-PNS activates insulin secretion during meals
-SNS inhibits insulin secretion & stimulates glucagon release when glucose levels drop |
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Term
| What is diabetes mellitus? What is the difference between Type 1 and Type 2 diabetes? |
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Definition
hyperglycemia with increase glucose in urine
-blood glucose levels greater than ability of kidneys to reabsorb it
Type 1: insulin dependent
-insulin secretion is impaired
Type 2: insulin independent
-tissues are insensitive to secreted insulin |
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