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The Pancreas
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The Pancreas
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Functions of the Pancreas
1. Exocrine Gland – Digestive System Pancreatic juices released into small intestine for chemical digestion (catabolism). Amylase (pancreatic) - enzyme that digests starch. Lipase - enzyme that digests lipids. Protease - enzyme that digests proteins.
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Also in pancreatic juices:
Sodium Bicarbonate - neutralizes HCl. Additional Digestive Enzymes Trypsinogen trypsin digests protein (zymogens) Ribonuclease digests RNA. Deoxyribonuclease digests DNA.
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-cells site of insulin synthesis.
2. Endocrine Gland – Regulates Metabolism The islets of Langerhans (Pancreatic islets) are clusters of endocrine cells in the pancreas. -cells site of insulin synthesis. -cells site of glucagon synthesis. *Ghrelin – also from pancreas (and fundus of stomach), triggers hunger. delta-cells site of somatostatin synthesis.
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The Glycemic Index (GI)
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Insulin and Glucagon Insulin: peptide hormone made by cells
If blood glucose rises (e.g. after a meal) insulin is released. Insulin causes cells in body to take up glucose (e.g. ↓ blood glucose). Also causes liver to synthesize glycogen and other anabolic activities.
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Glucagon: peptide hormone made by cells
If blood glucose falls (e.g. in between meals) glucagon is released. Causes liver to hydrolyze glycogen into glucose (e.g. ↑ blood glucose) Also causes fats and proteins to be converted into glucose (called gluconeogenisis) and other catabolic activities.
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When blood Glucose is high Insulin is released to make
blood Glucose lower (normal) Cells in your body up-take the glucose
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When blood Glucose is low Glucagon is released to make
blood Glucose higher (normal) Liver is key site: Hepatocytes liberate Glucose stores (glycogen) and use fats & proteins to make more glucose * *Glycogenolysis
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Diabetes Mellitus Type I – “Juvenile Onset” (IDDM)
Type II – “Adult Onset” (NIDDM)
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Neurons can only use glucose!
and don’t require insulin (use Glut-2-trans). Low blood glucose, e.g., hypoglycemia, can impair CNS resulting in dizziness, speech problems and loss of consciousness. Unconsciousness => “hypoglycemic coma" often resulting from "insulin shock”.
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Insulin Levels
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The Glycemic Index (GI)
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Comparison of Molecules (120 Kcal each)
Glucose Sucrose Ethanol 2 slices of bread. 1 glass of orange juice. 1 shot of bourbon.
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Glucose Sucrose Ethanol ↑ Aldehydes ↑ Aldehydes 2 slices of bread
1 glass of orange juice 1 shot of bourbon 60 kcal glucose + 60 kcal fructose Starch => glucose CNS Depressant ~96 kcal used by all cells in body ~48 kcal used by all cells in body ~24 kcal used by all cells in body ~24 kcal hits Liver for Metabolism ~72 kcal hits Liver for Metabolism ~96 kcal hits Liver for Metabolism Glucose-6-℗ Glucose-6-℗ ↑ Aldehydes ↑ Acetate ↑ Citrate ↑ VLDL ↑ Aldehydes ↑ Uric acid ↑ VLDL + ↓NO = ↑BP Makes Glycogen ~0.5 kcal used for de novo Lipogenesis ↑ de novo Lipogenesis ↑ de novo Lipogenesis ↑ Insulin Dislipidemia Inhibits Ghrelin No effect on Ghrelin ↑Insulin resistance
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Metabolic Syndrome Numerous metabolic risk factors in one individual, including: High Blood Pressure Abdominal Fat High blood Triglyceride levels High Uric Acid levels Insulin resistance State of chronic Inflammation Risks - cardiovascular disease and Type II diabetes mellitus. Est. over 50 million Americans have this condition. Hypothesized link to over consumption of high-fructose corn syrup (HFCS) and metabolic syndrome.
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