Muscle Coordination and Contraction Quiz

Which of the following best describes the sliding filament theory of muscle contraction?

• Myosin filaments shorten during contraction.

• Actin filaments slide over myosin filaments.

• Calcium ions are released into the bloodstream.

• ATP is not required for muscle contraction.

In the context of the neuromuscular junction, what role does acetylcholine play?

• It inhibits muscle contraction.

• It is a neurotransmitter that stimulates muscle contraction.

• It is responsible for the reuptake of calcium ions.

• It directly binds to actin filaments.

What is the primary effect of an action potential reaching the axon terminal of a motor neuron?

• It causes the release of neurotransmitters into the synaptic cleft.

• It leads to the immediate contraction of the muscle fiber.

• It decreases the permeability of the neuron membrane.

• It generates a new action potential in the muscle fiber.

Which of the following statements about muscle contraction is true?

• The length of the sarcomere increases during contraction.

• Myosin heads bind to actin filaments in the presence of ATP.

• Calcium ions are released from the sarcoplasmic reticulum only after contraction begins.

• The Z-lines move further apart during contraction.

What initiates the process of muscle contraction at the neuromuscular junction?

• The binding of calcium ions to troponin.

• The release of acetylcholine from the motor neuron.

• The depolarization of the muscle fiber membrane.

• The hydrolysis of ATP by myosin.

During action potential propagation along a muscle fiber, which ion is primarily responsible for depolarization?

• Potassium (K+)

• Sodium (Na+)

• Calcium (Ca2+)

• Chloride (Cl-)

What is the role of the T-tubules in muscle contraction?

• They store calcium ions.

• They transmit action potentials deep into the muscle fiber.

• They synthesize ATP for muscle contraction.

• They connect muscle fibers to tendons.

Which of the following correctly describes the role of calcium ions in muscle contraction?

• Calcium ions bind to myosin, allowing it to attach to actin.

• Calcium ions are released from the sarcoplasmic reticulum and bind to troponin.

• Calcium ions inhibit the action of acetylcholine.

• Calcium ions are responsible for the reuptake of ATP.

What happens to the muscle fiber when the action potential is terminated?

• Calcium ions are continuously released.

• Acetylcholine is broken down by acetylcholinesterase.

• The muscle fiber remains contracted indefinitely.

• ATP production ceases immediately.

In the sliding filament model, what is the result of ATP hydrolysis?

• It causes the myosin head to detach from actin.

• It provides energy for the power stroke.

• It allows calcium ions to bind to troponin.

• It initiates the release of acetylcholine.