ATP provides the energy for muscle contraction. The three mechanisms for ATP regeneration are creatine phosphate, anaerobic glycolysis, and aerobic metabolism. Creatine phosphate provides about the first 15 seconds of ATP at the beginning of muscle contraction. Anaerobic glycolysis produces small amounts of ATP in the absence of oxygen for a short period. Aerobic metabolism utilizes oxygen to produce much more ATP, allowing a muscle to work for longer periods. Muscle fatigue, which has many contributing factors, occurs when muscle can no longer contract. An oxygen debt is created as a result of muscle use. The three types of muscle fiber are slow oxidative (SO), fast oxidative (FO) and fast glycolytic (FG). SO fibers use aerobic metabolism to produce low power contractions over long periods and are slow to fatigue. FO fibers use aerobic metabolism to produce ATP but produce higher tension contractions than SO fibers. FG fibers use anaerobic metabolism to produce powerful, high-tension contractions but fatigue quickly.
fast glycolytic (FG)
muscle fiber that primarily uses anaerobic glycolysis
fast oxidative (FO)
intermediate muscle fiber that is between slow oxidative and fast glycolytic fibers
slow oxidative (SO)
muscle fiber that primarily uses aerobic respiration
1. Muscle fatigue is caused by ________.
A) buildup of ATP and lactic acid levels
B) exhaustion of energy reserves and buildup of lactic acid levels
C) buildup of ATP and pyruvic acid levels
D) exhaustion of energy reserves and buildup of pyruvic acid levels
B
2. A sprinter would experience muscle fatigue sooner than a marathon runner due to ________.
A) anaerobic metabolism in the muscles of the sprinter
B) anaerobic metabolism in the muscles of the marathon runner
C) aerobic metabolism in the muscles of the sprinter
D) glycolysis in the muscles of the marathon runner
A
3. What aspect of creatine phosphate allows it to supply energy to muscles?
A) ATPase activity
B) phosphate bonds
C) carbon bonds
D) hydrogen bonds
B
4. Drug X blocks ATP regeneration from ADP and phosphate. How will muscle cells respond to this drug?
A) by absorbing ATP from the bloodstream
B) by using ADP as an energy source
C) by using glycogen as an energy source
D) none of the above
D
1. Why do muscle cells use creatine phosphate instead of glycolysis to supply ATP for the first few seconds of muscle contraction?
Creatine phosphate is used because creatine phosphate and ADP are converted very quickly into ATP by creatine kinase. Glycolysis cannot generate ATP as quickly as creatine phosphate.
2. Is aerobic respiration more or less efficient than glycolysis? Explain your answer.
Aerobic respiration is much more efficient than anaerobic glycolysis, yielding 36 ATP per molecule of glucose, as opposed to two ATP produced by glycolysis.