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31 Cards in this Set
- Front
- Back
Obj.
Indicate the specific sites of insulin and glucagon synthesis |
insulin:
synthesized by beta cell in pancreas glucagon: synthesized by alpha cells in pancreas |
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What 4 organs play a major role in metabolism?
How do they communicate? |
liver
adipose muscle brain -communicate via nervous system, availability of substrates, & variation in plasma hormone levels |
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Obj.
List the effects of insulin rise in patients blood |
decreases blood glucose
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The energy metabolism is controlled by what (5/6) hormones?
These hormones induce storage when food is available & degradation of storage when it is not |
1. insulin
2. glucagon 3. epinephrine 4. norepinephrine 5. cortisol (chronic stress) & GH |
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Insulin affects the anabolism (building) of what (3)?
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glycogen
triacylglycerols protein |
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Obj.
Cite the regulators of insulin secretion |
Stimulated by-
1. glucose (strongest stimuli, more secreted) 2. AAs (Arg) 3 GI hormones Inhibited by- 1. low dietary fuel (glucose, ATP) 2. stress, trauma, extreme exercise (presence of epinephrine) |
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Active insulin results from posttranslational cleavage of what two precursors?
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preporinsulin
proinsulin |
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Obj.
Predict the metabolic effects of insulin on: carbohydrates triacylglycerides protein synthesis |
carbohydrates:
-increases glycogen synthesis & glucose uptake -inhibits gluconeogenesis & glycogenolysis triacylglycerides: -inhibits hormone-sensitive lipase, decreasing release of FAs (decrease degradation in ADIPOSE) -increases glucose uptake by adipose, increasing G-3-P -activates lipoprotein lipase (LPL), increasing free FAs protein synthesis: -stimulates AA uptake & protein synthesis |
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Insulin secretion is measured using the plasma concentration of what?
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C-peptide
(concentrations are directly proportional) -has longer half life, is degraded in kidney |
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Effects of Insulin
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*insulin is stored in granules & secreted by exocytosis when needed, has a 6 min half life
Inhibits: gluconeogenesis (liver) glycogenolysis (liver) Activates: glycogen synthesis (muscle & liver) glucose uptake (muscle & adipose)(NOT RBCs, brain, or liver!!!!) =decreased blood glucose |
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What is insulin degraded by?
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insulinase
*degraded in liver and kineys |
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Obj.
General consequences of hypoglycemia |
-confusion
-aberrant behavior -blood glucose < or = 40 mg/dL -coma |
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Beta cells sense glucose via ___________ activity, and secrete insulin in response.
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glucokinase
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Obj.
What are the two types of hypoglycemia symptoms/onset? |
1. sudden lowering of glucose (Adrenergic)
-symptoms due to epinephrine release 2. gradual decrease of brain glucose (Neuroglycopenic) -symptoms due to brain malfunction |
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Obj.
What are the symptoms of each type |
Andrenergic:
-anxiety -palpitations -tremors -sweating Neuroglycopenic: -headache -confusion -slurred speech -seizures -coma -death |
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The absorption of a carbohydrate rich meal results in:
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insulin secretion
glucagon inhibition --> overall increase in glucose an insulin |
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T/F
Insulin stimulates the synthesis of enzymes necessary for protein sythesis |
TRUE
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Obj
what hormonal changes accompany hypoglycemia |
-decreased (low) insulin*
-increased (high) glucagon* -increased (high) epinephrine* -increased cortisol -increased growth hormone |
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Glucagon & epinephrine are important for (short/long) term regulation of blood glucose
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short term
**cortisol and growth hormone are important for long term** |
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Obj.
Why is hypoglycemia a medical emergency? How can it be corrected? |
CNS requires continuous supply of glucose
Severe prolonged hypoglycemia causes brain death *treated w/ glucose administration! |
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Epinephrine induces:
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glycogenolysis
lipolysis *epinephrine OVERRIDES normal glucose-stimulated release of insulin= even if glucose is present, if epinephrine is there, insulin will not be secreted |
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Obj.
Cite different types of hypoglycemia |
Insulin-induced hypoglycemia:
-caused by diabetic (type 1) ppl taking insulin -treated w/ carb/glucose, eaten/injected depending on consciousness Postprandial hypoglycemia: -caused by high insulin release after meal -transient, recovers after eating -avoided by eating frequent small meals |
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Obj.
Explain insulin's mechanism of action |
1. Receptor tyrosine kinase phosphorylates Insulin receptor Substrates (IRS)
2. Phosphorylated IRS promotes activation of other protein kinases & phosphatases 3. Activation of enzymes leads to biological effects of insulin: increase: glucose uptake glycogen synthesis protein synthesis fat synthesis decrease: gluconeogenesis glycogenolysis lipolysis --altered gene expression |
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Obj
what are the effects of hypoglycemia and alcohol intoxication? |
-Degradation of ethanol leads to increased cystolic NADH
^reduction of pyruvate to lactate (lactic acidosis) ^conversion of OAA to malate -Decrease in pyruvate & OAA leads to decreased gluconeogenesis (bc precursors unavailable) ^leads to hypoglycemia |
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Formation of NADH can be decreased by taking ___________
This intake will result in what? |
Disulfram (aldehyde dehydrogenase inhibitor, halts ethanol metabolism)
Results in: flushing tachycardia hyperventilation nausea |
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T/F
glucagon and GLP-1 ("glucagon-like" incretin) are secreted by the same cells |
FALSE
glucagon is secreted by alpha cells in pancreas, GLP-1 secreted by neuroendocrine (L cells) in gut! -have similar function |
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Glucagon w/ epinephrine, cortisol, and growth hormone has (same/opposite) effect of insulin
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opposite
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In the liver, what does glucagon increase?
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glycogenolysis
gluconeogenesis FA oxidation (forming ketone bodies & acetyl CoA) AA uptake (for gluconeogenesis) (= opposite effect of insulin!!!) (glucagon + epi also activate ketogenesis, where insulin inhibits) |
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Stimulation/inhibition of glucagon secretion
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Stimulation:
low blood glucose (hypoglycemia) high AA (hypoglycemia caused by insulin) epinephrine (increase glucose use) Inhibition: high blood glucose high insulin |
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Obj
Fasting hypoglycemia is rare but can occur under what conditions? If untreated what may occur? |
-hepatocellular damage (low glucose production)
-adrenal insufficiency -fasting + large alcohol intake -overuse of glucose by body in presence of pancreatic beta tumor (elevated insulin) pt may: lost consciousness have convulsions slip into coma |
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alcohol consumption should be avoided in individuals that are ___________, _____________, or _______________
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fasting, engaged in prolonged strenuous exercise, or taking insulin
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