Sliding filament theory flashcards

What is sliding filament theory?

A model explaining how muscles contract by the sliding of actin and myosin filaments.

What are myofilaments?

Protein filaments in muscle fibers responsible for contraction: primarily actin and myosin.

True or false: Myosin is a thick filament.

True, because myosin filaments are thicker than actin filaments.

What are the roles of actin?

Actin provides the structure for muscle contraction and interacts with myosin.

What happens during muscle contraction?

Actin filaments slide over myosin, shortening the muscle fiber.

Difference between actin and myosin

Actin is a thin filament; myosin is a thick filament.

Fill in the blank: Myosin heads bind to ______.

Actin filaments during muscle contraction.

What does ATP do in muscle contraction?

ATP provides energy for myosin heads to detach and reattach to actin.

What is a sarcomere?

The structural unit of a muscle fiber, defined by Z-lines.

True or false: All muscle fibers are the same.

False, because there are different types, such as slow-twitch and fast-twitch.

What initiates muscle contraction?

The release of calcium ions from the sarcoplasmic reticulum.

What is the role of calcium in muscle contraction?

Calcium binds to troponin, causing tropomyosin to move and expose actin binding sites.

What is tropomyosin?

A protein that blocks actin's binding sites in a resting muscle.

Fill in the blank: The sliding filament theory was proposed by ______.

Hugh Huxley and Jean Hanson.

True or false: Muscle relaxation occurs when calcium levels are high.

False, because muscle relaxation occurs when calcium is pumped back into the sarcoplasmic reticulum.

What is the function of the Z-line?

The Z-line anchors the actin filaments and defines the boundaries of a sarcomere.

What causes muscle fatigue?

Accumulation of metabolic byproducts and depletion of energy sources.

What is cross-bridge cycling?

The process of myosin heads attaching to actin, pulling, detaching, and reattaching.

Fill in the blank: The ______ is the functional unit of muscle contraction.

Sarcomere.