Anatomy: Muscle Contraction

Front

What is a sarcomere?

Back

The basic structural and functional unit of a muscle fiber, consisting of a repeating pattern of actin and myosin filaments.

Front

What happens to the H zone during muscle contraction?

Back

The H zone decreases in size as actin filaments slide over myosin filaments.

Front

What role does myosin play in muscle contraction?

Back

Myosin pulls on actin filaments to facilitate muscle contraction.

Front

What attaches to actin to form the cross bridge?

Back

Myosin attaches to actin to form the cross bridge during muscle contraction.

Front

What is the relationship between actin filaments when a muscle is relaxed?

Back

Actin filaments are far apart from each other when the muscle is relaxed.

Front

Define muscle contraction.

Back

The process where muscle fibers shorten and generate force, typically involving the sliding of actin and myosin filaments.

Front

What is the role of calcium in muscle contraction?

Back

Calcium ions bind to troponin, causing a conformational change that allows myosin to bind to actin.

Front

What is tropomyosin?

Back

A protein that blocks the binding sites on actin filaments, preventing muscle contraction when the muscle is relaxed.

Front

Explain the sliding filament theory.

Back

The theory that muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere.

Front

What is the function of troponin in muscle contraction?

Back

Troponin binds to calcium and moves tropomyosin away from actin's binding sites, allowing contraction.