Muscle Tissue and Contraction Concepts

Which of the following is NOT a type of muscle tissue found in the human body?

• Cardiac muscle

• Smooth muscle

• Connective muscle

• Skeletal muscle

Which characteristic is unique to cardiac muscle tissue compared to smooth and skeletal muscle?

• It is involuntary.

• It is striated.

• It contains intercalated discs.

• It has multiple nuclei per cell.

Which type of muscle tissue is primarily responsible for voluntary movements like lifting a book?

• Cardiac muscle

• Smooth muscle

• Skeletal muscle

• Involuntary muscle

What term describes the ability of muscle tissue to return to its original length after being stretched?

• Extensibility

• Elasticity

• Excitability

• Contractility

What are the two main protein filaments responsible for muscle contraction within a sarcomere?

• Actin and Troponin

• Myosin and Tropomyosin

• Actin and Myosin

• Troponin and Tropomyosin

Which statement accurately describes how a sarcomere shortens during muscle contraction?

• The thick and thin filaments themselves shorten in length.

• The Z-lines move further apart.

• The thick and thin filaments slide past each other.

• The M-line expands, pushing the filaments together.

What is the crucial role of ATP in the cross-bridge cycle of muscle contraction?

• It causes the myosin head to bind to the actin filament.

• It provides the energy for the power stroke.

• It enables the myosin head to detach from the actin filament.

• It directly activates the actin filament.

How do calcium ions initiate muscle contraction?

• They directly bind to the myosin heads, activating them.

• They cause the thick filaments to shorten, pulling on the thin filaments.

• They bind to troponin, causing tropomyosin to move and expose myosin binding sites on actin.

• They hydrolyze ATP, releasing energy for the power stroke.