Muscle Metabolism Aerobic respiration: produces large amounts of ATP but requires O 2 to function, waste products: water, CO 2 Anaerobic fermentation: produces small amounts of ATP in absence of O 2 waste product: lactic acid (major factor in fatigue)
Muscle Metabolism There are three phases to muscle metabolism Each is designed to give muscle tissue energy during strenuous activities
Muscle Metabolism 1.Immediate energy: during intense exercise oxygen is quickly depleted in muscle(6sec) so ATP is made by grabbing Pi from donor molecules and adding it to ADP to make ATP Donor molecule: Creatine kinase grabs a Pi from creatine phosphate (CP) and adds to ADP to make ATP, nearly all ATP during short burst are produced this way (phosphagen system)
Muscle Metabolism 2.Short term energy: once the phosphagen system is depleted the body goes into anaerobic respiration. It can generate energy for 40 sec in intense activity 3.Long term energy: after 40 sec the body cardiovascular system catches up and is able to deliver the needed oxygen to the muscles for aerobic respiration
Fatigue Fatigue: the gradual weakness and loss of contractility ATP production decreases as glucose is used up Low levels of ATP slows Na/K pumps Lactic acid inhibits ATP production K+ in the ECF makes cell less excitable ACh becomes depleted
Oxygen Debt Oxygen Debt: occurs after exercise. Due to the following Oxygen reserves: oxygen is dissolved in tissues in the body that are depleted first and need to be replaced Phosphagen system: ATP must be made, then broken to give Pi back to creatine Oxidizing lactic acid: most of lactic acid will be converted into glucose in the presence of oxygen Metabolic rate: if body temp is high the metabolic rate is high and requires oxygen to break down molecules
Muscle Fibers Slow oxidative (SO): Red fibers with lots of mitochondria and blood capillaries better for aerobic activity Fast glycolytic (FG): White fibers with large storage of phosphagen and lactic systems better for quick responses but not endurance