Physiology Week 3 Lecture 5
Physiology Week 3 Lecture 5 IPHY 3470
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This 4 page Class Notes was uploaded by Sydney Lazzell on Tuesday September 6, 2016. The Class Notes belongs to IPHY 3470 at University of Colorado at Boulder taught by Christopher DeSouza in Fall 2016. Since its upload, it has received 18 views. For similar materials see Human Physiology 1 in integrated physiology at University of Colorado at Boulder.
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Date Created: 09/06/16
IPHY 3470: Human Physiology 1 Week 3 – Lecture 5 Chalk-Talk Cell Death o Necrosis: trauma, lack of oxygen, toxins o Apoptosis: programmed cell death o Highly regulated/conserved o Protects cell growth/cell death (keeps balance) § Caspase 3 Stem Cells 1. Totipotent: any cell type à any tissue à any organ a. 4 days to start differentiating 2. Pluripotent: many but not all cell types/tissues/organs 3. Multipotent: main source is bone marrow a. Most narrow in scope b. E.g. EPC’s Cell Metabolism 1. ATP: 1-3 seconds a. In cytosol 2. Creatine Phosphate: 5-15 seconds a. In cytosol 3. CHO metabolism a. Anaerobic glycolysis: 30sec-3minutes b. Aerobic glycolysis: <40 minutes c. Both in cytosol 4. Fat metabolism: >40 minutes a. In mitochondria 5. Protein metabolism: no time line a. In mitochondria Lecture Slides – Cell Metabolism Continued Breakdown of Carbohydrates o Glycolysis happens in the cytosol o Normal glucose levels: fasting: 70-100 mg/dL o Anaerobic = pyruvate à lactate o Aerobic = pyruvate is moved into mitochondria à Acetyl-CoA o More ATP from fat than glucose but takes longer o High intensity = glucose for ATP o Most highly regulated substance = glucose Breakdown of Fat o Adipose tissue à blood à cytoplasm à mitochondria o 1 glucose = 34 ATP o High intensity o 1 fatty acid = 122 ATP o Long duration Glycolysis o Uptake of glucose from cells depends on several factors: o Type of tissue o Levels of glucose in the blood & tissue o Presence of insulin (triggers glucose transporters) o Physiological status of the tissue (e.g. muscle) o Most tissue require insulin except contracting muscle o Can take in more glucose à metabolism is increasing o Nerve & brain tissue consume large amounts of glucose o Muscle primary glucose disposal unit; largest tissue containing enzyme for glycolysis o Only monosaccarides (1) are broken down o Glucose à 2 ATP à 2 Pyruvate/2 Lactate Homo. Fermentation o Anaerobic glycolysis o NAD must be recycled after reduction to NADH o When ATP demand is high & O2 is depleted, lactate dehydrogenase catalyzes the reduction of NADH by pyruvate to yield lactate and NAD (needed for Step 6) Lactate Dehydrogenase (anaerobic) o NADH + H NAD o o Pyruvate à Lactate o Enzyme = LDH o Exists as isozymes (> 1 form) o NAD goes back to Step 6 to keep system going o All forms occur in most tissues o M type = muscle & liver ; H type = heart Glycolytic Pathway (10 steps) Step 1: ATP ADP + H Glucose Glucose 6 Phosphate (G-6-P) o Enzyme = hexokinase (1 rate limiting step) Step 2: G-6-P Fructose 6 Phosphate o Enzyme = phosphohexoisomerase Step 3: ATP ADP + H F-6-P F1,6DP o Enzyme = PFK (2 rate limiting enzyme) Step 4: F1,6DP G3P & Dihydroxyacetone phosphate o Enzyme = aldolase Step 5: G3P Dihydroxyacetone phosphate o Enzyme = triose isomerase Step 6: NAD + Pi NADH + H2O G3P 1,3 –DPG o Enzyme = GAPDH o First “high energy” intermediate formation (NADH) o Used for lactate production or shuttles electrons o No NAD = glycolysis shuts down Step 7: ADP + H ATP 1,3- DPG 3-PG o Enzyme = phosphoglycerate kinase o First ATP generation Step 8: 3-PG 2-PG o Enzyme = phosphoglyceromutase Step 9: H2O 2-PG PEP o Enzyme = enolase Step 10: ADP + Pi ATP PEP Pyruvate rd o Enzyme = pyruvate kinase (3 rate limiting enzyme) o End of glycolysis *All enzymes are in the cytosol *Net ATP generated = 2