Sliding Filament Model

Front

What is the sliding filament model?

Back

The sliding filament model explains how muscles contract by the sliding of actin and myosin filaments past each other, leading to shortening of the sarcomere.

Front

What is a sarcomere?

Back

A sarcomere is the basic structural and functional unit of a muscle fiber, defined as the segment between two Z lines.

Front

What happens to the sarcomere during muscle contraction?

Back

During muscle contraction, the sarcomere shortens as the actin filaments slide over the myosin filaments.

Front

What is the role of calcium ions in muscle contraction?

Back

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

Front

What is the function of ATP in muscle contraction?

Back

ATP provides the energy required for the power stroke of the myosin cross bridge, allowing muscle contraction to occur.

Front

What is the sarcoplasmic reticulum?

Back

The sarcoplasmic reticulum is a specialized endoplasmic reticulum in muscle cells that stores and releases calcium ions.

Front

What is the sarcolemma?

Back

The sarcolemma is the plasma membrane of a skeletal muscle cell, which surrounds the muscle fiber.

Front

What are myofilaments?

Back

Myofilaments are the contractile proteins within muscle fibers, primarily composed of actin (thin filaments) and myosin (thick filaments).

Front

What is the role of troponin in muscle contraction?

Back

Troponin is a protein that, when bound to calcium, causes tropomyosin to move away from actin's binding sites, allowing myosin to attach.

Front

What is the role of tropomyosin in muscle contraction?

Back

Tropomyosin is a protein that blocks the binding sites on actin filaments, preventing contraction until calcium binds to troponin.