Muscle Physiology: Muscle Fiber Contraction

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What happens to the mechanical response of a muscle fiber when the frequency of action potentials is increased?

It decreases beyond the level of maximal tetanic tension

It remains constant

It increases up to the level of maximal tetanic tension (correct)

It decreases

At what load does the maximum velocity of muscle fiber shortening occur?

At zero load (correct)

At 50% of maximum load

At minimum load

At maximum load

What is the primary source of fuel for muscle fibers at the beginning of exercise?

Muscle glycogen (correct)

Fatty acids from the blood

Glucose from the blood

Creatine phosphate

What is the primary mechanism of ATP formation in the mitochondria of muscle fibers?

Oxidative phosphorylation Signup and view all the answers

What is the optimal sarcomere length for generating maximum isometric tetanic tension?

Lo Signup and view all the answers

What is a contributing factor to muscle fatigue during high-intensity exercise?

Increase in H+ concentration Signup and view all the answers

What is the primary mechanism by which muscle tension is increased?

Recruiting additional motor units in a muscle Signup and view all the answers

What type of exercise increases a fiber's capacity for oxidative ATP production?

Long-duration, low-intensity exercise Signup and view all the answers

Which type of motor unit is recruited first during muscle contraction?

Slow-oxidative motor units Signup and view all the answers

What is the result of increased synthesis of actin and myosin in muscle fibers?

Increased strength Signup and view all the answers

What is the primary function of antagonistic muscles around a joint?

To flex and extend a limb Signup and view all the answers

What type of muscle contraction is characterized by a high velocity of movement?

Contraction with high motor-unit recruitment Signup and view all the answers

What is the primary reason why muscle tension is greater than the load in an isometric contraction?

To compensate for the mechanical disadvantage of the lever system Signup and view all the answers

What is the primary cause of hypocalcemic tetany?

Decreased extracellular Ca2+ concentration Signup and view all the answers

What is the role of calcium ions in sodium channels?

To interact with the exterior surface of sodium channels to regulate their opening Signup and view all the answers

What is the primary defect in muscular dystrophies?

Defects in muscle-membrane-stabilizing proteins Signup and view all the answers

What is the primary effect of heavy exercise on muscle contraction?

Involuntary tetanic contractions Signup and view all the answers

What is the primary mechanism of muscle contraction in the lever system?

Isometric contraction Signup and view all the answers