2Muscle MetabolismGoals:Describe three ways in which ATP is regenerated during muscle contractionRelate the oxygen deficit to causes of muscle fatigue
3Muscle Metabolism Muscle have only a 4 to 6 second supply of ATP ATP must be continually regenerated via one of three pathways in the muscle.
4Muscle Metabolism Direct phosphorylation of ADP by creatine phosphate These pathways are:Direct phosphorylation of ADP by creatine phosphateAnaerobic glycolysisAerobic respiration
5Muscle Metabolism Creatine Phosphate Phosphorylation Active muscles can use all ATP within a few twitches.Creatine Phosphate is a high energy storage moleculeThe transfer of its high energy phosphate to ADP can provide up to 16 seconds of ATP in a muscle.Creatine phosphate is regenerated during rest.Its money for health food companies.
6Muscle Metabolism Creatine Phosphate Phosphorylation This pathway is used for very quick bursts of muscle activity, such as sprinting.
7Figure 9.19a Pathways for regenerating ATP during muscle activity. Coupled reaction of creatinephosphate (CP) and ADPEnergy source: CP(a) Direct phosphorylationOxygen use: NoneProducts: 1 ATP per CP, creatineDuration of energy provision:15 secondsCreatinekinaseADPCPATP
8Muscle Metabolism Glycolysis and Lactic Acid Formation This pathway generates ATP after the Creatine phosphate system is exhausted.Actively contracting muscles compress arteries, reducing blood flow and oxygen.This produces anaerobic conditions which produce lactic acid.
9Figure 9.19b Pathways for regenerating ATP during muscle activity. Energy source: glucoseGlycolysis and lactic acid formation(b) Anaerobic pathwayOxygen use: NoneProducts: 2 ATP per glucose, lactic acidDuration of energy provision:60 seconds, or slightly moreGlucose (fromglycogen breakdown ordelivered from blood)Glycolysisin cytosolPyruvic acidReleasedto bloodnet gain2Lactic acidO2ATP
10Muscle Metabolism Glycolysis and Lactic Acid Formation This pathway only produces about 5% as much ATP as aerobic respiration but does it twice as fast.This pathway extends the ATP supply up to 1 minute of vigorous activity.
11Short-duration exercise Figure Comparison of energy sources used during short-duration exercise and prolonged-duration exercise (1 of 2).Short-duration exerciseATP stored inmuscles isused first.ATP is formedfrom creatinephosphateand ADP.Glycogen stored in muscles is brokendown to glucose, which is oxidized togenerate ATP.
12It coincides with muscle fatigue. Muscle Metabolism Glycolysis and Lactic Acid Formation The Big Lie by State Ed DepartmentThe build up of lactic acid leads does NOT lead to muscle soreness following exercise.It coincides with muscle fatigue.
13Muscle Metabolism Muscle Fatigue Muscle fatigue is the inability to contract even in the presence of stimuli.
14Muscle Metabolism Muscle Fatigue Muscle fatigue is the inability to contract even in the presence of stimuli.It is NOT due to a lack of ATP. This would lead to contractures. This is seen with writers cramp.
15Muscle Metabolism Muscle Fatigue Ionic disturbances are the most likely cause of muscle fatigue:Potassium ion lost from the muscle cellsInterference of Calcium regulation
16Muscle Metabolism Aerobic Respiration This pathway produces 95% of the ATP.This pathway occurs in the mitochondria and requires oxygen.
18Muscle Metabolism Aerobic Respiration Muscle glycogen provides the major source of glucose followed by blood glucose and then fats.It provides the most ATP but is slower because of all the enzymatic steps.
19Figure 9.19c Pathways for regenerating ATP during muscle activity. Energy source: glucose; pyruvic acid;free fatty acids from adipose tissue;amino acids from protein catabolism(c) Aerobic pathwayAerobic cellular respirationOxygen use: RequiredProducts: 32 ATP per glucose, CO2, H2ODuration of energy provision: HoursGlucose (fromglycogen breakdown ordelivered from blood)32O2H2OCO2Pyruvic acidFattyacidsAminoAerobic respirationin mitochondriaATPnet gain perglucose
20Prolonged-duration exercise Figure Comparison of energy sources used during short-duration exercise and prolonged-duration exercise (2 of 2).Prolonged-duration exerciseATP is generated by breakdown of severalnutrient energy fuels by aerobic pathway.This pathway uses oxygen released frommyoglobin or delivered in the blood byhemoglobin. When it ends, the oxygendeficit is paid back.
21Muscle Metabolism Aerobic Respiration This pathway is used for long periods of exercise such as cross county and marathon events.
23Deep down we are all turkeys Muscle Fiber TypeDeep down we are all turkeys
24Deep down we are all turkeys Remember white meat/ dark meat? Muscle Fiber TypeDeep down we are all turkeys Remember white meat/ dark meat?
25Muscle Fiber TypeMuscle fibers are divided into two types based on their metabolism.Slow oxidative fibers (Red Meat)AerobicMyoglobin present (Red Color)Large number of mitochondriaLow glycogen contentSlow rate of fatigueGood for endurance activities
26Muscle Fiber TypeMuscle fibers are divided into two types based on their metabolism.2. Fast Glycolytic FibersAnaerobicMyoglobin content is low (White Color)Glycogen content is highFatigues quicklyFew mitochondriaShort term intense movements
27Muscle Fiber TypeA third muscle type, the Fast Oxidative Fiber has characteristics of both muscle types. These muscle can convert to the other types based on training.
28Adaptation to Exercise Endurance exercising will:Increase the number of capillaries surrounding the muscle fibers (why)Increase the number of mitochondria (why)May convert some of the fast glycolytic fibers to fast oxidative fibersIncrease the efficiency of the heart (why)
29Adaptation to Exercise Resistance exercising will:Increase the increase the size of the muscle fibersIncrease the amount of connective tissue between the fibersMay convert some of the to fast oxidative fibers to fast glycolytic fibers