1/5/15 Chapters 7 and 8: Aerobic and Anaerobic Metabolism Chapters 7 and 8: Aerobic and Anaerobic Metabolism 1.  Produc=on of ATP 2.  Use of ATP during exercise 3.  Animal adapta=ons to reduced oxygen All movements require ATP •  ATP not transferred between cells •  Physiological work is ATP-­‐limited –  We can only work as fast as cells produce ATP at any given =me •  Survival depends on individual’s ability to synthesize all required ATP ATP produced: ADP + phosphates + food energy à ATP ATP used: ATP à ADP + phosphates + Energy for cell func=ons Aerobic catabolism •  More efficient than anaerobic –  Greater ATP yield per mol glucose •  Primary mode of ATP synthesis •  Brain cells can only func=on via aerobic pathways Aerobic and Anaerobic pathways •  Aerobic catabolism (cellular respira=on): reac=on that converts sugars into ATP –  ATP produced in presence of oxygen C6H12O6 + 6O2 à 6CO2 + 6H2O + ATP –  O2 can come from stored sources (myoglobin) •  Anaerobic glycolysis: series of reac=ons that converts glucose to lac=c acid –  ATP produced in absence of oxygen C6H12O6 à 2 C3H6O3 + ATP Aerobic catabolism •  Four biochemical ‘sets’ of reac=ons: 1.  Glycolysis: glucose à pyruvic acid +NADH Krebs cycle: pyruvic acid is oxidized in mitochondria 2.  Electron transport chain (ETC): movement of electrons creates energy 3.  Oxida>ve phosphoryla>on: ADP à ATP from energy out of ETC 1 1/5/15 Anaerobic glycolysis: Lac=c acid Anaerobic glycolysis: Lac=c acid •  Energy dense molecule can be used as fuel •  Longer glycolysis con=nues, more LA builds up •  Energy dense molecule can be used as fuel •  Longer glycolysis con=nues, more LA builds up –  Longer reten=on and greater buildup in cells has harmful affects –  Longer reten=on and greater buildup in cells has harmful affects •  Gluconeogenesis: conversion of LA à glucose C6H12O6 à 2 C3H6O3 + ATP •  Requires ATP AND O2 •  Can be done in different cells than where synthesized VIDEO Aerobic and Anaerobic pathways Aerobic Fuel
Aerobic and Anaerobic pathways Anaerobic Aerobic Fuel
Anaerobic Any food Only glucose (carbohydrates) All cells Muscles, Lungs Where in body Where in body Where in cell Where in cell Mitochondria Cytosol NET yield NET yield 2 mol ATP / mol glucose End products End products CO2 and H2O Lac=c acid -­‐ Can’t be used for energy -­‐ Used as energy source Chapters 7 and 8: Aerobic and Anaerobic Metabolism 1.  Produc=on of ATP 2.  Use of ATP during exercise 3.  Animal adapta=ons to reduced oxygen 38 mol ATP / mol glucose All movements require ATP •  Method of ATP produc=on (pathway) varies by type of movement 1.  Burst exercise => sprints, salmon leaping waterfalls 2.  Sustained exercise => running, migratory flight 2 1/5/15 Sustained movements need LOTS of ATP Sustained movements need LOTS of ATP •  Glycolysis goes on for a long =me •  Implica=ons of long-­‐term glycolysis? •  Where does all the glucose come from? –  Depends on =me 1.  Large buildup of lac=c acid 2.  Causes muscle fa=gue: reduc=on in muscle’s ability to generate power 3.  Need lots of glucose •  Where does the glucose come from? Sustained movements need LOTS of ATP •  Where does all the glucose come from? –  Depends on =me –  Depends on type of muscle fibers used Slow oxida>ve (SO) •  ATP from aerobic catabolism •  More mitochondria •  More Succinic DH (aerobic-­‐
catalyzing enzyme) •  More myglobin •  Used for sustained exercise Fast glycoly>c (FG) •  ATP from anaerobic glycolysis •  Few mitochondria •  More LDH (glycolysis-­‐
catalyzing enzyme) •  Low myglobin content •  Used for sprints, bursts Sustained movements need Where does all the glucose come from? –  Depends on =me –  Depends on type of muscle fibers used –  Depends on rela=ve amounts of each fiber type in muscles –  Single muscle can have both muscle fiber types –  Depends on dura=on of exercise Organisms switch between aerobic and anaerobic pathways during exercise ATP source depends on exercise dura=on •  Exercise pace slows with increasing dura=on –  Due to biochemistry of ATP produc=on •  Short dura=on – ATP produced mainly via glycolysis •  Longer races – ATP produced via aerobic catabolism Metabolic transi=on phases 1.  Oxygen deficit –  Exercise starts abruptly, but delivery of O2 to cells starts gradually –  ATP demand met by anaerobic glycolysis, using O2 stored in =ssues 1. 3 1/5/15 Metabolic transi=on phases 2.  Pay-­‐as-­‐you-­‐go phase –  Pulmonary and circulatory systems increase rate of O2 delivery –  ATP produced in cells from respired air à aerobic catabolism Metabolic transi=on phases 3.  Excess post-­‐exercise consump=on (EPOC) –  Rate of O2 uptake slows gradually, even though cells no longer need as much –  “Breathing heavy” –  Reasons are poorly understood 2. 3. How do we determine MR during exercise? •  Treadmills and wind tunnels: measure O2 consump=on during running/flight How do we determine MR during exercise? •  Radio telemetry: some radio collars can transmit physiological data! How do we determine MR during exercise? •  Time-­‐energy budgets: categorize behaviors and record average =me spent in each over day Chapters 7 and 8: Aerobic and Anaerobic Metabolism 1.  Produc=on of ATP 2.  Use of ATP during exercise 3.  Animal adapta>ons to reduced oxygen 4 1/5/15 Anoxic and hypoxic environments Anoxic and hypoxic environments •  Most vertebrates can’t live long in reduced O2 environments •  Metabolic depression: extreme lowering of MR –  Hypoxia: low O2 –  Anoxia: NO O2 –  S=ll must use more carbohydrates overall because glycolysis is less efficient •  But, some do... HOW?!?!? Anoxic and hypoxic environments •  Metabolic depression: extreme lowering of MR –  S=ll must use more carbohydrates overall because glycolysis is less efficient •  Shim to anaerobic glycolysis •  Some have greater O2 stores in other =ssues Oxygen regula=on and conformity 1.  Regula>on: maintain aerobic catabolism at steady rate, regardless of available O2 2.  Conformity: reduc=on in O2 consump=on as environmental availability decreases –  More myoglobin Oxygen regula=on and conformity •  Low-­‐oxygen dwellers can regulate at a much larger range –  Greater capacity to adapt to fluctua=ng O2 –  Low O2 environments are omen fatal to conformer species All organisms limited by VO2 Max •  VO2 Max: Individual’s peak rate of O2 consump=on –  é VO2 max = é longer pay-­‐as-­‐you-­‐go phase because ATP produced faster –  Declines with age 5 1/5/15 All organisms limited by VO2 Max •  Smaller animals tend to have higher VO2 max All organisms limited by VO2 Max •  Individual varia=on due to gene=cs AND training intensity and dura=on 6