Muscle Energetics

Metabolism The sum of processes by which we acquire energy, channel energy into useful functions, and dissipate energy from our bodies

Energy The ability to do work. Work requires motion in the direction of the exerted force.

4 Main Types of Energy Chemical, Electrical. Mechanical and Heat

Physiological Work All forms of energy are not equally capable of doing physiological work. We are not capable of using heat to do any form of physiological work…it is wasted energy. Examples of Physiological Work Synthesis of macromolecules such as proteins, carbohydrates and lipids Generation of electrical or chemical gradients Muscle Contraction

Max Kliber “Fire of Life” Life is a combustion process You are using oxygen to burn fuel (food) to create energy (and waste heat) Oxygen Heat Metabolism

You Consume O 2 & Food to Produce Energy Hydrocarbon Fuel + O 2 CO 2 + H 2 O Heat Combustion in a Pop Bottle Demonstration

Different Fuels (Foods) Produce Different Amounts of Energy Lipids (fats) = 9.3 kcal/gram Protein = 4.1 kcal/gram Carbohydrates = 4.1 kcal/gram

Mechanisms of Energy (ATP) Production Oxidative Phosphorylation 5-10 seconds Anaerobic Respiration 1-2 minutes Aerobic Respiration Conditioning dependent All 3 major categories of food can be degraded through these processes

Each “fuel” demonstrates a relationship between the amounts of: O 2 consumed ATP produced CO 2 produced

Oxidative Phosphorylation

ATP Used for transfer, not storage  Stores enough for 4-6 seconds of activity An active skeletal muscle fiber may require some 600 trillion molecules of ATP per second. At rest a skeletal muscle produces more ATP than it needs

ATP transfers this extra energy to creatine creating a high-energy compound, creatine phosphate. ATP + creatine  ADP + creatine phosphate or phosphocreatine A resting muscle contains about 6x as much creatine phosphate as ATP

Creatine Monohydrate Supplementaion  Increase intracellular stores creatine phosphate  Increase anaerobic capacity  Delay onset of muscular fatigue Does

Creatine Monohydrate Supplementation Does Not  Make you stronger / faster  Increase muscle mass  Decrease body fat %  Increase aerobic capacity

Creatine Monohydrate Supplementation Possible Side Effects  Muscle cramps, pulls, strains, etc.  Dehydration  Liver / Kidney stress  Atrophy of bank account

Anaerobic Respiration C 6 H 12 O 6  2CO 2 + Lactic Acid + 2ATP

Glycolysis a 6 carbon glucose molecule breaks down into 3 carbon pyruvic acid costs 2 molecules of ATP yields 4 molecules of ATP for a net of 2 ATP CCCCCC + ATP  CCCCCC Pyruvic Acid 2 ATP

System Drawbacks: It can only produce 2 molecules of ATP at a time As pyruvic acid levels rise it is converted to lactic acid

Anaerobic RespirationLab We will be testing four different drinks to see which will give us the most energy

1.In Muscle Cells- During extraneous activities, the oxygen in the muscle tissue is decreased to an extent that aerobic respiration does not occur at a sufficient rate. Hence, there is a buildup of lactic acid and your muscles get tired 2. In Yeast- The fermentation end product is ethyl alcohol, and CO 2 What happens when fermentation occurs?

So how do we decide which is best?

Energy + Glucose Ethanol + Carbon Dioxide + Energy Chemical Formula for Anaerobic Respiration We can measure the carbon dioxide released by each drink in the enzyme

Lab Procedure CO2 Gas Sensor to measure total concentration of CO2 CO 2 Gas Sensor

Lab Procedure Incubate the yeast solution in a 37 – 40 water bath Label the five test tubes G, C, F, M, and W Pour 2.5 mL of Gatorade into the test tube labeled G  Pour 2.5 mL of Coke into the test tube labeled C  Pour 2.5 mL of fruit juice into the test tube labeled F  Pour 2.5 mL of milk into the test tube labeled M  Pour 2.5 mL of water into the test tube labeled W Lightly stir the yeast suspension to mix the yeast that settled to the bottom. Put 2.5 mL of the yeast suspension into all five of the test tubes. Then incubate the test tubes for 10 minutes in the water bath. Place the Gas Sensor, and start collecting the data. for 4 minutes.

Aerobic Respiration C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O+ 36ATP

Pyruvic Acid Conversion 2 Pyruvic Acid molecules break off 1 carbon each The carbon bonds with Oxygen and is exhaled The 2 carbon acetic acids combine with Coenzyme A to form Acetyl CoA CCCCCC OOOO + Coenzyme A = Acetyl CoA

The Krebs Cycle Acetyl CoA bring 2 carbons to add to the 4 carbon molecule making a 6 carbon molecule 6 carbon citric acid is broken down into a 5 carbon and then a 4 carbon molecule CO 2 is given off in each reaction Ion carriers (NADPH and FADH) pick up e- along the way oaidfadf h

The Electron Transport Chain Ion carriers FADH and NADH release electrons The e- move down chain releasing energy as they go 34 molecules of ATP are formed per glucose molecule The final e- acceptor is Oxygen  water (moisture in breath as you exhale)

As the rate of ATP production rises so does the rate of oxygen consumption. At periods of peak activity oxygen can’t diffuse into the muscle fiber fast enough to make necessary ATP. This causes Glycolysis to become the primary source of ATP This system produces enough energy to last about 90 seconds

MUSCLE FATIGUE Physiological inability of a muscle to contract.

Muscle fatigue and return to resting state Many causes: ◦Lack of O 2 in the muscle or in the blood ◦Lack of glucose or glycogen store ◦Accumulation of lactic acid ◦Accumulation of calcium ions in inappropriate cell compartments

Causes of Muscle Fatigue Lack of O 2 in the muscle or in the blood Lack of glucose or glycogen store Accumulation of lactic acid Accumulation of calcium ions in inappropriate cell compartments

OXYGEN DEBT ETC Becomes Blocked ◦No ATP ◦No Regeneration of Ion Carriers (NAD and FAD) Forced into Glycolysis (anaerobic) Lactic Acid Fermentation ◦resulting in muscle fatigue, pain and cramps

Your Brain Needs Oxygen! Mammalian brains use ATP much faster than can be produced anaerobically  these brains must have O 2 ! Failure to supply oxygen to the brain leads to neuron death.

Lactic Acid Can Be Used Later We can metabolize lactic acid

Mechanisms of ATP production and use Mechanisms of ATP production Mode of operation ATP yield ATP rate - production at onset ATP rate - production Return to normal Aerobic catabolism using pre- existing O2 Non steadySmallFastHighFast Aerobic catabolism SteadyHighSlowModerate Phosphagen use Non steadySmallFastHighFast Anaerobic glycolysis Non steadyModerate - small FastHighSlow

INTERACTION OF ENERGY SYSTEMS ImmediateShort-termLong-term

Energy Systems for Exercise Energy Systems Mole of ATP/min Time to Fatigue Immediate: ATP - PCr (ATP & phosphocreatine) 4 5 to 10 sec Short Term: Glycolytic (Glycogen-Lactic Acid) to 2 min Long Term: Oxidative 1 Unlimited time

Energy Metabolism Aerobic Energy Sources ◦Primarily fatty acids ◦Then carbohydrate and ATP Anaerobic Energy Sources ◦Carbohydrates (gycolysis) ◦Lactate and ATP