mmm m

What is the primary role of the sarcoplasmic reticulum in muscle cells?

• It acts as the site for protein synthesis.

• It stores and releases calcium ions during muscle contraction and relaxation.

• It produces ATP for muscle contraction.

• It binds acetylcholine at the neuromuscular junction.

Which protein primarily composes the thick filaments in muscle cells?

• Actin

• Myosin

• Troponin

• Tropomyosin

What is the function of troponin in muscle contraction?

• It stores calcium ions within the muscle fiber.

• It binds to myosin to facilitate contraction.

• It regulates the interaction between actin and myosin by binding to calcium ions.

• It breaks down acetylcholine in the synaptic cleft.

What occurs during the 'power stroke' phase of the cross-bridge cycle?

• ATP binds to myosin, causing it to detach from actin.

• Myosin pulls the actin filament toward the center of the sarcomere.

• Calcium ions are released from the sarcoplasmic reticulum.

• Acetylcholine binds to its receptor at the neuromuscular junction.

Which structure serves as the attachment point for actin filaments and maintains the structural integrity of the sarcomere?

• Myosin filament

• H-zone

• Sarcoplasmic reticulum

• Z-disk

What is the role of acetylcholinesterase at the neuromuscular junction?

• It synthesizes acetylcholine.

• It binds to acetylcholine receptors.

• It releases calcium ions from the sarcoplasmic reticulum.

• It breaks down acetylcholine to terminate the signal for muscle contraction.

Which of the following is a characteristic symptom of Myasthenia Gravis?

• Enhanced neuromuscular transmission

• Drooping eyelids

• Rapid eye movements

• Increased muscle growth

What is the primary composition of thin filaments in muscle cells?

• Myosin and troponin

• Actin and myosin

• Actin, troponin, and tropomyosin

• Myosin and tropomyosin

What triggers the release of calcium ions from the sarcoplasmic reticulum?

• The detachment of myosin from actin

• The binding of acetylcholine to its receptor

• The binding of ATP to myosin

• An action potential in the motor neuron

Which type of acetylcholine receptor is predominantly found at the neuromuscular junction?

• GABA receptors

• Muscarinic acetylcholine receptors

• Nicotinic acetylcholine receptors

• Dopamine receptors