Muscle Tissue Quiz

Which of the following is NOT a property of muscle tissue?

• A. Contractility

• B. Excitability

• C. Fluidity

• D. Elasticity

What property allows muscle fibers to return to their original shape after being stretched?

• A. Contractility

• B. Distensibility

• C. Elasticity

• D. Conductivity

What happens to the Z-discs during muscle contraction, according to the sliding filament theory?

• A. They move apart from each other.

• B. They move toward the M-line.

• C. They break down.

• D. They move toward the A-band.

What is the role of thin filaments during muscle contraction?

• A. They remain stationary while thick filaments move.

• B. They slide toward the center of the sarcomere.

• C. They detach from the Z-discs.

• D. They shorten, causing the sarcomere to expand.

At rest, what is the typical membrane potential of a skeletal muscle fiber?

• -40 mV

• -70 mV

• -90 mV

• 0 mV

What is the purpose of the sodium/potassium pump in muscle fibers?

• To pump sodium and potassium ions across the membrane using ATP.

• To generate calcium for muscle contraction.

• To open leak channels in the muscle membrane.

• To depolarize the sarcolemma.

During depolarization, which ion enters the muscle fiber?

• Potassium (K⁺)

• Calcium (Ca²⁺)

• Sodium (Na⁺)

• Chloride (Cl⁻)

Which neurotransmitter is released into the synaptic cleft during muscle contraction?

• Dopamine

• Serotonin

• Acetylcholine

• Norepinephrine

Which of the following steps occurs FIRST in the excitation phase of muscle contraction?

• Sodium ions enter the muscle fiber.

• Calcium ions bind to troponin.

• Acetylcholine binds to receptors on the motor end plate.

• Calcium channels in the axon terminal open.

What happens to tropomyosin when calcium binds to troponin?

• It moves to expose the active sites on actin.

• It detaches from the sarcomere.