L5.3.3.3: Energy for Muscle Contraction

• ENERGY FOR MUSCLE CONTRACTION

  ATP

  ● Immediate source of energy for muscle contraction

  ● Stored in muscle fibers in small amounts that are quickly used up

  ● After this initial time, other pathways must be utilized to produce ATP
• 3 WAYS TO GENERATE ATP

  • Direct phosphorylation of ADP by creatine phosphate (CP)
  • Aerobic respiration
  • Anaerobic glycolysis and lactic acid formation
• Direct phosphorylation of ADP by creatine phosphate (CP)

  ● Fastest

  ● Muscle cells store CP, a high energy molecule

  ● After ATP is depleted, ADP remains

  ● CP transfers a phosphate group to ADP to regenerate ATP

  ● CP supplies are exhausted in less than 15 seconds

  ● About 1 ATP is created per CP molecule
• Aerobic respiration

  ● Glucose is broken down to carbon dioxide and water, releasing energy (about 32 ATP)

  ● A series of metabolic pathways occurs in the mitochondria

  ● This is a slower reaction that requires continuous oxygen

  ● Carbon dioxide and water are produced
• Anaerobic glycolysis and lactic acid formation

  ● Reaction that breaks down glucose without oxygen

  ● Glucose is broken down to pyruvic acid to produce about 2 ATP

  ● Pyruvic acid is converted to lactic acid

  ● This reaction is not as efficient, but is fast

  ○ Huge amounts of glucose are needed

  ○ Lactic acid produces muscle fatigue