Sliding Filament Model

Which type of muscle tissue is characterized by branched, striated fibers with intercalated discs and involuntary control?

• Skeletal muscle

• Smooth muscle

• Cardiac muscle

• Connective muscle

Which of the following is NOT a general characteristic of all muscle tissue?

• Extensibility

• Elasticity

• Voluntary control

• Excitability

What does the root word "rectus" in muscle names like "rectus femoris" or "rectus abdominis" indicate about the muscle?

• Its location is deep.

• Its fibers run straight.

• Its shape is triangular.

• It moves away from the midline.

What are the long, cylindrical structures found inside a muscle fiber that contain repeating sections called sarcomeres?

• Myofibrils

• Tendons

• Ligaments

• Fascicles

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What are the thin filaments in a sarcomere primarily composed of?

• Myosin

• Actin

• Troponin

• Tropomyosin

What happens to the thick and thin filaments themselves during muscle contraction according to the sliding filament model?

• They shorten significantly.

• They lengthen to increase muscle size.

• They slide past each other without shortening.

• They break down and reform.

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

• To cause the myosin head to bind to actin.

• To provide energy for the power stroke.

• To cause the myosin head to detach from actin.

• To block the actin binding sites.

What ion is released to initiate muscle contraction by binding to troponin, causing tropomyosin to move and expose myosin binding sites on actin?

• Sodium ions

• Potassium ions

• Calcium ions

• Chloride ions