Kinesiology 203 Lecture 15 - Metabolism I - University of Calgary PDF

KINESIOLOGY 203 Activity: Health, Fitness and Performance Metabolism I: Anaerobic and aerobic energy pathways Jenny Zhang Faculty of Kinesiology October 29, 2024 Objectives By the end of this lecture, you should be able to: Understand factors controlling the rate of energy production Know the...

KINESIOLOGY 203 Activity: Health, Fitness and Performance Metabolism I: Anaerobic and aerobic energy pathways Jenny Zhang Faculty of Kinesiology October 29, 2024 Objectives By the end of this lecture, you should be able to: Understand factors controlling the rate of energy production Know the contribution of each energy pathway during different exercise intensity-durations Describe the main energy pathways: Immediate system Anaerobic glycolytic system Aerobic/oxidative system (aerobic glycolysis, oxidative phosphorylation, and fat oxidation) 2  Recap: Energy transfer in our body The chemical bonds in macronutrients (CHO, lipids, proteins) in our food are a form of potential energy But they are not usable in our body Also, the chemical bonds that hold these elements together are relatively weak Our body needs to convert these to high-energy compounds (ATP) Growth and repair, Cellular and nerve potential functions Intake Human body output energy Kinetic energy (motion) 3 https://quizlet.com/329809035/chapter-8-bild1-diagram/  www.perspectivesinmedicine.org Summary: Metabolic energy pathways Advanced Online Article. Cite this article as Cold Spring Harb Perspect Med doi: 10.1101/cshperspect.a029744 Albumin FFA (Blood flow x concn) HbO2 Glucose O2 Blood (FABPpm; FAT/CD36; FATP) (GLUT1; GLUT4) PM Cytosol Glucose Glycogen ATG lipase HS lipase HK Glycogen MG lipase phosphorylase FFA FABPc G-6-P G-1-P ATPase TG Fatty acyl-CoA ATP CK ADP + Pi Glycerol synthase PFK phosphate NAD+ acyltransferase Fatty Cr mtCK PCr (GPAT-1; GPAT-2) acyl-CoA ATP NADH Diacylglycerol ATP ADP acyltransferase (DGAT) Pyruvate Lactate LDH CPT-I mtOM (ACT) (FAT/CD36) (MCT) (ANT) Pi mtIM CPT-II NAD+ PDH ADP ATP Pi Matrix NADH CO2 + Pi transporter β-Oxidation H+ Fatty Acetyl-CoA F0-F1 ATPase acyl-CoA NAD+ NAD+ NADH TCA cycle E T Exercise Metabolism NADH C ATP H+ H+ CO2 H2O O2 Hargreaves and Spriet. 2018. Cold Spring Harb Perspect Med. 8(8). pii: a029744. Figure 1. (Legend continues on following page.) 3 4  Lipolysis Glycolysis Immediate FFA Glucose FABP Blood GLUT 4 Cytosol ATP TG Fatty Acyl- CoA Glucose 6 - P Glycogen ATP à ADP + Pi 2s ATP Cr + Pi ß PCr 15 s Pyruvate Lactate ATP à Pi + ADP Mitochondria Fatty Acyl- CoA TCA cycle ATP ß Pi + ADP Acetyl- Produces: Β – Oxidation CoA ATP ETC Produces: Produces: NADH NAD+ Acetyl-CoA FADH2 FAD CO2 H2 O 5 Contribution of energy systems Exercise duration Exercise intensity 10,000 m 1,500 m 400 m 100 m Sprint Immediate Glycolysis (lactate) Immediate Glycolysis (lac) Immediate Immediate Glycolysis (aer.) Glycolysis (aer.) Glycolysis (lac) Glycolysis (lactate) Glycolysis (aerobic) Glycolysis (aer.) Lipolysis Lipolysis Lipolysis Lipolysis 6 ATP turnover during a 30-s all-out cycling sprint test Parolin et al. (1999) AJP Endocrinol Metab 7 Immediate system  Lipolysis Glycolysis Immediate FFA Glucose FABP Blood GLUT 4 Cytosol ATP TG Fatty Acyl- CoA Glucose 6 - P Glycogen ATP à ADP + Pi 2s ATP Cr + Pi ß PCr 15 s Pyruvate Lactate ATP à Pi + ADP Mitochondria Fatty Acyl- CoA TCA cycle ATP ß Pi + ADP Acetyl- Produces: Β – Oxidation CoA ATP ETC Produces: Produces: NADH NAD+ Acetyl-CoA FADH2 FAD CO2 H2O 9 Immediate system (ATP-PCr system) Stored ATP ATP ATP → ADP + Pi + H+ Phosphocreatine PCr + ADP + H+ → ATP + Cr CK Fastest and simplest energy system Substrate-level metabolism, does not need oxygen PCr breakdown releases 10.3 kcal/per mol This is more than needed to reconstitute ATP PCr storage enough for only ~8-13 s of maximal effort 10  PCr breakdown depends on exercise intensity and ATP is protected in the immediate system 100 ATP Resting value (%) Exhaustion 50 PCr 0 0 2 4 6 8 10 12 14 Howlett et al. (1998) AJP-RICP Time (s) 11 Anaerobic glycolytic system  Lipolysis Glycolysis Immediate FFA Glucose FABP Blood GLUT 4 Cytosol ATP TG Fatty Acyl- CoA Glucose 6 - P Glycogen ATP à ADP + Pi 2s ATP Cr + Pi ß PCr 15 s Pyruvate Lactate ATP à Pi + ADP Mitochondria Fatty Acyl- CoA TCA cycle ATP ß Pi + ADP Acetyl- Produces: Β – Oxidation CoA ATP ETC Produces: Produces: NADH NAD+ Acetyl-CoA FADH2 FAD CO2 H2O 13 Anaerobic glycolytic pathway Involves breakdown of glucose or glycogen End product of anaerobic is lactate Glycolysis produces 2 ATPs and Glycogenolysis produces 3 ATPs Glucose Blood GLUT 4 ATP Cytosol Glycogen Glucose 6 - P ATP 4 x ATP Pyruvate Lactate Mitochondria 14 Lactate and exercise intensity Howlett et al. (1998) AJP-RICP 15 Glycolysis 16 Anaerobic glycolytic pathway Predominates during early stages (e.g., 1-2 minutes) of high-intensity exercise Does not require oxygen Carbohydrate is the only macronutrient that can generate ATP anaerobically Blood ~5 g Muscle ~500 g Liver ~80 g Limitations: Does not produce a large amount of ATP Produces H+ ions H+ reduces blood and muscle pH and results in muscle (peripheral) fatigue Lactate is a fuel – it can convert to glucose (gluconeogenesis) and produce energy 17 Aerobic/Oxidative system  Lipolysis Glycolysis Immediate FFA Glucose FABP Blood GLUT 4 Cytosol ATP TG Fatty Acyl- CoA Glucose 6 - P Glycogen ATP à ADP + Pi 2s ATP Cr + Pi ß PCr 15 s Pyruvate Lactate ATP à Pi + ADP Mitochondria Fatty Acyl- CoA TCA cycle ATP ß Pi + ADP Acetyl- Produces: Β – Oxidation CoA ATP ETC Produces: Produces: NADH NAD+ Acetyl-CoA FADH2 FAD CO2 H2O 19 Mitochondria! 20 Aerobic system Involves 3 main processes: Aerobic glycolysis Krebs cycle (TCA/Citric acid cycle) Electron transport chain Involves cellular respiration because oxygen is required Occurs inside the mitochondria Number and density of mitochondria determine the aerobic capacity of that muscle Denser near capillaries to optimize O2 delivery Aerobic pathway has a large energy production capacity 21 Aerobic glycolysis Pyruvate Lactate mt membrane acetyl-CoA Krebs cycle Pyruvate gets converted to acetyl-CoA in the mitochondria Irreversible step Acetyl-CoA will enter the Krebs cycle Combined with NAD+ and FAD will produce ATP, NADH, and FADH2 22 Krebs cycle schematic Products: 2 ATP 6 NADH 2 FADH2 💵 NADH 💵 FADH2 23 Electron transport chain Oxidative phosphorylation: consists of ETC and ATP synthase reaction NADH and FADH2 carry electrons to ETC As electrons are passed along, ATP synthase converts ADP to ATP 💵 FADH2 💵 NADH 24 ATP yield from aerobic glycolysis 1 NADH + H+ is worth 2.5 ATP 1 FADH2 is worth 1.5 ATP Glycolysis (before entering mitochondria): 2 ATP 4 NADH = 10 ATP Total yield: Krebs cycle: 4 ATP 2 ATP 10 NADH (25 ATP) 2 FADH2 (3 ATP) Oxidative phosphorylation: 6 NADH = 15 ATP Contrast this with anaerobic glycolysis 2 FADH2 = 3 ATP 25 Intro to fat oxidation Glucose Given that aerobic glycolysis and fat oxidation both enter the Free fatty acid Krebs cycle, if you were a cell, Pyruvate how would you choose which path to take? What factors acetyl-CoA would you need to consider? β-oxidation Krebs cycle ETC 26