Sliding Filament Theory of Muscle Contraction

Front

What is the sliding filament theory?

Back

The sliding filament theory explains how muscles contract by the sliding of actin and myosin filaments past each other, resulting in muscle shortening.

Front

What are the two main types of muscle filaments involved in contraction?

Back

The two main types of muscle filaments are actin (thin filaments) and myosin (thick filaments).

Front

What is the role of calcium ions in muscle contraction?

Back

Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the myosin-binding sites on actin, allowing contraction to occur.

Front

What is the function of the sarcoplasmic reticulum in muscle cells?

Back

The sarcoplasmic reticulum stores and releases calcium ions, which are crucial for muscle contraction.

Front

Define 'sarcomere'.

Back

A sarcomere is the basic contractile unit of muscle tissue, defined as the segment between two Z discs.

Front

What is the significance of the Z disc in a sarcomere?

Back

The Z disc anchors the thin filaments (actin) and defines the boundaries of each sarcomere.

Front

What neurotransmitter is released at the neuromuscular junction to stimulate muscle contraction?

Back

Acetylcholine is the neurotransmitter released at the neuromuscular junction that stimulates muscle contraction.

Front

What is the role of ATP in muscle contraction?

Back

ATP provides the energy required for myosin heads to detach from actin and re-cock for another contraction cycle.

Front

What is the difference between isotonic and isometric contractions?

Back

Isotonic contractions involve muscle shortening with movement (e.g., lifting weights), while isometric contractions involve muscle tension without shortening (e.g., holding a weight steady).

Front

What is the A band in a sarcomere?

Back

The A band is the region of the sarcomere that contains the thick filaments (myosin) and is responsible for the dark appearance of muscle under a microscope.