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32 Cards in this Set
- Front
- Back
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Anabolism vs Catabolism:
General Tissue Involved in Storage/Use Insulin Levels Regulators |
Anabolism: Fed-state, build-up
Store Glycogen (Liver, Muscle), Fat (Liver, Adipose), Protein (Muscle) Insulin HIGH (inhibits catabolism) Regulated by Insulin Catabolism: Fasting, break down Use Glycogen (Liver, Muscle), Fat (Adipose), Protein (Muscle) Insulin LOW Breakdown regulated by Glucagon, Stress Hormones |
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These cells synthesize prepro-insulin which is cleaved to ______, which then is _______ to produce insulin.
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Pancreatic BETA cells synth prepro-insulin, cleaved to proinsulin (then cleaved to insulin by cleaving C peptide)
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50% insulin is removed by _____ during the first pass.
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Liver
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Role of amylin.
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Suppress postprandial (post-meal) glucagon and slow gastric emptying, having the effect of slowly increasing blood sugar
It is released along with insulin |
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Describe how a pancreas cell releases insulin. Begin with glucose entering the cell.
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GLUT2 allows for entry of glucose
Glucose-->G6P-->Glycolysis, TCA-->ATP ATP increase depolarizes K+ channel (closes), forces Ca2+ channel to open (influx) INSULIN RELEASE (via secretory vesicles exocytosed) |
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Insulin secretion is related to the concentration of _______.
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Glucose
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Why is insulin secretion faster at breakfast than at lunch and dinner?
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Breakfast tends to be carb heavy, large increase in insulin
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Why is insulin biphasic?
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First: Glucose ready to go (orange juice), immediate spike in insulin
Second: Glucose released more slowly (like from carbs), delayed insulin release More insulin for carbs than proteins! |
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What is basal insulin?
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Baseline insulin in fasting state (night time).
Always need insulin! |
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Describe the molecular events that proceed insulin binding insulin receptor.
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Insulin Receptor = Tyrosine Receptor Kinase
Phosphylates Insulin Receptor Substrate (IRS) IRS proteins stimulate downstream effects Sends Glut-# (active glucose transporter) to cell membrane Glut-4# imports glucose |
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Describe the 4 glucose transporter proteins.
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GLUT-1: all tissues; high glucose affinity; mediates basal uptake esp in brain
GLUT-2: glucose sensor in beta cells; also in L, GI, kidney (lower affinity for glucose) GLUT-3: ALL TISSUES; high affinity in neurons GLUT-4: insulin regulated; found in skeletal muscle and adipose tissue |
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What is the effect of insulin on the liver?
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Inhibits ketogenesis
Inhibits gluconeogenesis (don't need to make glucose if you've just eaten) Stimulates glycogenesis Stimulates FA synthesis |
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What is the effect of insulin on muscle?
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Stimulates glucose uptake via GLUT-4
Stimulates glycogenesis (Exercise promotes glucose transporter via diff transporter!) Increase Prot Synth |
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What is the effect of insulin on adipose tissue?
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Stimulates glucose uptake via GLUT-4
FA uptake via lipoprotein lipase for TG storage (lipogenesis) |
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What is the effect of insulin on the brain?
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BRAIN IS NOT INSULIN DEPENDENT FOR GLUCOSE
But it will inhibit your appetite (it promotes satiety) |
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Brain uses ______ readily for energy.
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Ketones
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What energy reserves are tapped when the body enters a catabolic state?
Which organs can use which sources of energy? What are insulin levels like in this state? |
Glucose from liver glycogen, then GN (brain prefers glucose)
Fatty acids: from TG in adipose, lipase release FA (used by all tissues EXCEPT Brain) Ketone bodies made in liver from FA (production depends on FA delivery)--used by all tissues EXCEPT liver INSULIN IS LOW |
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Glucagon:
Cells that make it Effect Regulation |
Large polypep made in islet ALPHA cells
Inhibited by GLUCOSE Effect = counter-regulatory to insulin, mainly in LIVER: Breaks down glycogen within minutes (GLYCOGENOLYSIS) Gluconeogenesis within hours (substrates are lactate, alanine; require energy) Ketogenesis Summ: GLUCAGON stimulates BREAKDOWN of glycogen (**opposite of insuline!***) |
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Glucagon-like peptides are cleaved from ______ by _____.
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Proglucagon by prohormone convertase
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GLP-1 vs GLP-2:
Effects |
GLP-1:
Secreted from intestinal L cells in response to meals Increase insulin, inhibit glucagon release--(this is why you have a better insulin response when you eat food, instead of injecting insulin) (Also targets stomach, brain (satiety)) GLP-2: Secreted with GLP-1 Acts on intestine to increase absorption, decrease motility |
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Function of Dipeptidyl Peptidase IV (DPP-IV)?
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Inactivates Circulating GLP-1
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Somatostatin is synthesized by _______.
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Hypothal
Pancreatic DELTA cell GI tract |
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SMS-14 vs SMS-28
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SMS = SOMATOSTATIN
SMS-14: Pancreas SMS-28: Gut Both inhibit GH, insulin release Both inhibit glucagon |
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Which SMS is better at inhibiting GH?
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SMS-28
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Which SMS is better at inhibiting glucagon?
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SMS-14
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Which SMS is better at inhibiting insulin?
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SMS-28
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How does NE, E act as a counter-regulatory hormone?
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Catecholamine = Stress Hormone
Stimulate glycogenolysis, GN in liver, lipolysis (via Hormone Sensitive Lipase) It's sensitive to [glucose], even a small drop |
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How does cortisol act as a counter-regulatory hormone?
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Proteolysis, Gluconeogenesis in liver, insulin resistance (blunts insulin's actions so minimize glucose uptake--keeps more in the blood).
DAWN PHENOM STRESS RESPONSE |
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How does GH act as a counter-regulatory hormone?
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Lipolysis, insulin resistance
DAWN PHENOM STRESS RESPONSE |
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What is the dawn phenomenon?
Which counter-regulatory hormones exhibit this effect? |
5-6AM, insulin and glucose low
Cortisol and GH peak to maintain normal catabolism |
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Insulin deficiency and ______ lead to hyperglycemia.
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Counterregulatory hormone excess
(decreased glucose disposal bc of low insulin; inc'd hepatic glucose production bc of counterreg hormone excess) |
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Insulin deficiency and ______ lead to ketosis.
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Counterregulatory excess
(insulin deficiency leads to inc'd lipolysis; inc'd hepatic ketogensis due to inc'd counterreg hormones) |
