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20 Cards in this Set
- Front
- Back
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what causes the K channels to close in the β cells?
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increased ATP from the metabolism of glucose (glycolysis, TCA cycle, oxidative phosphorylation)
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how do amino acids affect insulin and glucagon secretion?
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increase both b/c insulin is involved in protein synthesis and amino acids are the precursors of gluconeogenesis
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where is glucagon metabolized?
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liver and kidneys
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how does glucose and insulin affect glucagon release?
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increased levels of glucose and insulin inhibit glucagon release
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how does glucagon cause signal transduction?
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G proteins activate adenylate cyclase, which increases the synthesis of cAMP, which activates protein kinase A, which phosphorylates various enzymes
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how can cAMP regulate fuel metabolism in skeletal muscle, which lacks glucagon receptors?
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epinephrine binds to β2 receptors and activates adenylate cyclase
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which kinases are used by insulin and glucagon in signal transduction?
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insulin uses a tyrosine kinase (β subunit) and glucagon uses a serine kinase (protein kinase A)
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what makes epinephrine and NE catecholamines?
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benzene ring with 2 hydroxy groups and an amine group
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how does the structure of epinephrine differ from NE?
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epinephrine has a methyl group attached to the N
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where is the β1 adrenergic receptor found and what does it bind? what is its function?
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heart, NE; increases rate of contraction
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where is the β2 adrenergic receptor found and what does it bind? what is its function?
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liver, skeletal muscle, smooth muscle; binds epinephrine; mobilization of fuels
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where is the β3 adrenergic receptor found and what is its function?
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adipose tissue and to a lesser extent in skeletal muscle; FA oxidation and thermogenesis
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what is the function of the α1 adrenergic receptor?
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mediate vascular and smooth muscle contraction
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what would you expect to occur in the liver if cAMP phosphodiesterase was inhibited?
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cAMP phosphodiesterase decreases cAMP levels by hydrolyzing it to 5'-AMP. Therefore, you would expect a prolonged response to glucagon since cAMP levels would remain high
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what is the major factor determining whether skeletal muscles will use FAs or glucose as a fuel?
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[FAs] in the blood
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what is the half-life of Hgb in the bloodstream?
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12-14 weeks
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what causes MODY?
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mutation in pancreatic glucokinase; not enough glucose is metabolized to generate enough ATP to close the K channels and cause insulin release
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which hormone (other than somatostatin) inhibits insulin release?
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epinephrine stimulates energy utilization during fasting stress, trauma, exercise and therefore insulin is not needed
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how is signal transduction carried out in β adrenergic receptors?
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adenylate cyclase - cAMP system
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how is signal transduction carried out in the α1 adrenergic receptor?
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PIP2 system
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