Understanding Skeletal Muscle Physiology

What is the role of actin and myosin in muscle contraction?

• Actin and myosin are responsible for energy production in muscles.

• Actin and myosin prevent muscle contraction by maintaining muscle length.

• Actin and myosin are involved in the transport of oxygen in the blood.

• Actin and myosin work together to contract muscles by forming cross-bridges and sliding past each other.

Describe the process of excitation-contraction coupling.

• Excitation-contraction coupling only happens in cardiac muscles.

• Excitation-contraction coupling is the process where an action potential triggers calcium release, leading to muscle contraction.

• Calcium is released without an action potential.

• Muscle contraction occurs without calcium involvement.

What neurotransmitter is released at the neuromuscular junction?

• Acetylcholine

• Serotonin

• Dopamine

• Norepinephrine

How does the action potential lead to muscle contraction?

• Calcium is released only after muscle contraction begins.

• The action potential directly contracts the muscle fibers without calcium involvement.

• The action potential leads to muscle contraction by triggering calcium release, enabling actin and myosin interaction.

• Muscle contraction occurs only when the action potential is absent.

What are the main types of skeletal muscle fibers?

• Type X, Type Y, Type Z

• Type IIA, Type IIB, Type III

• Type A, Type B, Type C

• Type I, Type IIa, Type IIb

How do slow-twitch fibers differ from fast-twitch fibers?

• Slow-twitch fibers are primarily used for sprinting.

• Fast-twitch fibers are more efficient at burning fat.

• Slow-twitch fibers are endurance-oriented and fatigue-resistant, while fast-twitch fibers are power-oriented and fatigue quickly.

• Slow-twitch fibers are larger in size than fast-twitch fibers.

What is the significance of the sarcoplasmic reticulum in muscle contraction?

• The sarcoplasmic reticulum generates electrical impulses for muscle contraction.

• The sarcoplasmic reticulum stores and releases calcium ions, which are essential for muscle contraction.

• The sarcoplasmic reticulum provides energy directly to muscle fibers.

• The sarcoplasmic reticulum acts as a structural support for muscle cells.

Explain the role of calcium ions in muscle contraction.

• Calcium ions bind to troponin, enabling muscle contraction by allowing myosin to interact with actin.

• Calcium ions are primarily responsible for energy production in muscle cells.

• Calcium ions are released to decrease muscle tension during relaxation.

• Calcium ions inhibit muscle contraction by blocking actin sites.

What energy sources are primarily used during muscle activity?

• Carbon dioxide, water, and minerals

• Lactic acid, glycogen, and oxygen

• Fatty acids, protein, and nitrogen

• ATP, creatine phosphate, and glucose

How does ATP contribute to muscle contraction and relaxation?

• ATP directly causes muscle fibers to shorten.

• ATP is essential for both muscle contraction and relaxation by providing energy for myosin movement and facilitating calcium ion reuptake.

• ATP is only needed for muscle relaxation.

• ATP is not involved in calcium ion management during contraction.