Muscle Metabolism

1
Muscle Metabolism

• Aerobic respiration produces large amounts of
  ATP but requires O2 to function, waste products
  water, CO2
• Anaerobic fermentation produces small amounts of
  ATP in absence of O2 waste product lactic acid
  (major factor in fatigue)

2
Muscle Metabolism

• There are three phases to muscle metabolism
• Each is designed to give muscle tissue energy
  during strenuous activities

3
Muscle Metabolism

• 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)

4
Muscle Metabolism

1. 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
2. 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

5
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

6
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

7
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