Muscle Organization and Function Quiz

What is the largest unit in the organization of muscle?

• Fascicles

• Muscle Fibers

• Muscle

• Myofibrils

What is the function of sarcomeres in muscle fibers?

• To store energy

• To transport nutrients

• To facilitate contraction

• To protect the muscle

Which protein is a thick filament that interacts with actin to generate force?

• Actin

• Tropomyosin

• Myosin

• Troponin

What is the role of the neuromuscular junction (NMJ)?

• To store calcium ions

• To transmit electrical signals from the motor neuron to the muscle fiber

• To produce energy for muscle contraction

• To repair damaged muscle fibers

Which band in a sarcomere contains only thin filaments?

• A Band

• I Band

• H Zone

• M Line

What is the role of calcium (Ca²⁺) in muscle contraction?

• It binds to myosin, causing muscle contraction.

• It binds to troponin, causing a conformational change that moves tropomyosin.

• It binds to actin, forming a cross-bridge.

• It triggers the release of ATP from the sarcoplasmic reticulum.

Why is ATP important for muscle contraction?

• It provides energy for the release of calcium from the sarcoplasmic reticulum.

• It is required for myosin heads to detach from actin after a power stroke.

• It binds to troponin to initiate contraction.

• It is used to break down acetylcholine.

What is the function of the SERCA pump in muscle cells?

• It releases calcium into the cytoplasm to initiate contraction.

• It pumps calcium back into the sarcoplasmic reticulum for muscle relaxation.

• It breaks down acetylcholine to terminate muscle contraction.

• It provides ATP for muscle contraction.

Which characteristic is true of slow-twitch (Type I) muscle fibers?

• They are suited for short, high-intensity activities.

• They rely on anaerobic metabolism.

• They are high endurance and fatigue-resistant.

• They have low mitochondrial content.

What is the role of acetylcholine (ACh) in muscle contraction?

• It binds to myosin to initiate contraction.

• It triggers muscle contraction by binding to receptors on the muscle fiber's membrane.

• It breaks down ATP to provide energy for contraction.

• It pumps calcium back into the sarcoplasmic reticulum.