physio quiz 9

What is the consequence of crossbridge cycling in skeletal muscle?

Movement of only 10 micrometers.

What does thick myosin do during contraction?

Pulls thin myosin towards the M line.

What shortens during skeletal muscle contraction?

The sarcomere, I band, and H zone.

What does not shorten during skeletal muscle contraction?

The A band.

What must happen for skeletal muscle relaxation?

Stop crossbridge cycling by removing calcium.

What initiates calcium release in muscle contraction?

Motor neuron action potentials.

What is required for muscle relaxation?

Calcium must be returned to the sarcoplasmic reticulum.

How is calcium returned to the sarcoplasmic reticulum?

Using calcium ATPase pumps.

What is a muscle twitch?

Tension over time resulting from a single action potential.

What is the latent period in muscle twitch?

The delay before any tension develops.

What is the primary energy source for crossbridge cycling?

ATP.

What is the role of creatine phosphate in muscle energy?

Provides 1 ATP through substrate level phosphorylation.

What is produced from glycolysis?

2 ATP per glucose.

What happens to pyruvate during intense activity?

It is converted into lactate.

What is the aerobic process that produces ATP in muscle cells?

Krebs cycle.

How many ATP are produced in oxidative phosphorylation?

28-34 ATP.

What is isometric contraction?

When tension is less than load, no shortening occurs.

What is eccentric contraction?

When tension is less than load, muscle lengthens.

What is isotonic contraction?

When tension is greater than load, shortening occurs.

What is tetanus in muscle contraction?

Maintained contraction with increased tension.

What is the difference between unfused and fused tetanus?

Unfused tetanus allows partial relaxation; fused tetanus has no relaxation.

What are the types of myofibers?

Slow oxidative, fast oxidative, and fast glycolytic.

What is the effect of aerobic exercise on muscle fibers?

Increases vascularization and number of mitochondria.

What is the effect of anaerobic exercise on muscle fibers?

Increases myofiber diameter and glycolytic enzymes.

What factors contribute to muscle fiber types?

ATPase activity, resistance to fatigue, and vascularization.

What can cause muscle atrophy?

Disuse and some diseases.

What can cause muscle hypertrophy?

Exercise, especially anaerobic.