Review for Physiology of Muscle Contraction Quiz

What cells cause muscle fibers to contract?

• Neurons

• Myocytes

• Osteocytes

• Chondrocytes

What is found at the neuromuscular junction?

• Synaptic vesicles and acetylcholine

• Mitochondria and ribosomes

• Nucleus and Golgi apparatus

• Lysosomes and peroxisomes

Which of the following describes an overview of the events that occur at the neuromuscular junction?

• Release of neurotransmitters from the motor neuron and binding to receptors on the muscle fiber.

• Direct electrical connection between the motor neuron and muscle fiber.

• Exchange of ions directly between the motor neuron and muscle fiber.

• Muscle fiber releases neurotransmitters to stimulate the motor neuron.

After Acetylcholine binds to the muscle receptors and the action potential moves down through the T tubules, what is released from the terminal cisternae?

• Calcium ions

• Sodium ions

• Potassium ions

• Chloride ions

Calcium will bind to which of the following on the actin filament?

• Tropomyosin

• Troponin

• Myosin

• Actin

Binding of the calcium causes what to happen on the actin filament?

• It causes the actin filament to contract.

• It exposes the myosin-binding sites on the actin filament.

• It detaches the actin filament from the myosin.

• It breaks down the actin filament.

What bonds to the binding site on actin filaments that allows sliding of the filaments to occur?

• Myosin

• Tropomyosin

• Troponin

• Calcium ions

The bond between actin and myosin is called a ________________________.

• cross-bridge

• hydrogen bond

• ionic bond

• peptide bond

Using ______ as energy, the myosin heads pull the actin filaments into the center of the sarcomere, causing sliding of the filaments to occur.

• ATP

• GTP

• CTP

• UTP

A new molecule of ______ binds to the myosin head causing it to detach from the actin strand. As long as the active binding sites are still exposed, ______________ can bind to the next active site.

• A new molecule of ATP binds to the myosin head causing it to detach from the actin strand. As long as the active binding sites are still exposed, myosin can bind to the next active site.

• A new molecule of ADP binds to the myosin head causing it to detach from the actin strand. As long as the active binding sites are still exposed, actin can bind to the next active site.

• A new molecule of GTP binds to the myosin head causing it to detach from the actin strand. As long as the active binding sites are still exposed, tropomyosin can bind to the next active site.

• A new molecule of AMP binds to the myosin head causing it to detach from the actin strand. As long as the active binding sites are still exposed, troponin can bind to the next active site.