9.4 Flashcards
Hydrolysis of ATP by ___-ATPase energizes the cross-bridges, providing the energy for force generation.
myosin
One of the ways by which a muscle fiber can form ATP is the phosphorylation of ___ by creatine phosphate.
ADP
Creatine phosphate ___.
is used to convert ADP to ATP
What fuel substrates are used to produce ATP by oxidative phosphorylation in skeletal muscle fibers?
- blood glucose
- blood fatty acids
- glucose from muscle glycogen
When exercise intensity is sufficiently high, glycolysis begins to contribute an increasingly large fraction of the total ATP generated. The glucose for glycolysis can be obtained from two sources: (1) the ___ or (2) the stores of ___ within the contracting muscle fibers
blood; glycogen
Which of the following is NOT one of the four functions of ATP in skeletal muscle?
Movement of glucose from the extracellular fluid into the cytosol by Glucose/ATPase pumps.
Muscle fibers can make ATP in which of the following ways?
- glycolysis
- oxidative phosphorylation
- creatine phosphate breakdown
Which two of the following account for the use of oxygen when a person is repaying an “oxygen debt” after exercising?
- Extra oxygen is required to restore creatine phosphate and glycogen concentrations.
- Extra oxygen is required to metabolize accumulated lactic acid.
In muscle, the high energy molecule ___ ___ donates a high energy phosphate group to recharge ATP in the first few seconds of muscle contraction.
creatine phosphate
When a skeletal muscle experiences a reduction in its ability to produce tension during prolonged intense exercise, it is due to a phenomenon called muscle ___.
fatigue
During moderate intensity exercise, most of the ATP used for muscle contraction is formed by ___.
oxidative phosphorylation
If prolonged exercise intensity exceeds about 70% of the maximum rate of ATP breakdown, ___ contributes an increasingly significant fraction of the total ATP generated within skeletal muscle.
glycolysis
Which of the following is NOT a contributing factor in acute muscle fatigue?
Decrease in the cytosolic Pi concentration
(not [ADP]: reduces cross-bridge for power stroke, or cytosolic H+: acid during anaerobic glycolysis impairs Ca2+ handling, and not decrease cytosolic SDP inhibiting cross-bridge cycling)
In skeletal muscle fibers, ATP ___.
- is used for calcium transport back to the sarcoplasmic reticulum
- is used by myosin ATPase to energize the myosin cross bridge
- binding to myosin ATPase induces conformational changes that break the actin and myosin bond
Oxygen consumption remains elevated for a time following exercise to restore depleted reserves of ATP, creatine phosphate and glycogen. This depletion is referred to as the ___.
oxygen debt
