The Sarcomere

Front

What is the sarcolemma?

Back

The sarcolemma is the cell membrane of a muscle cell, which has T-tubules that fold into the cell to spread out the electrical impulse that triggers muscle contraction.

Front

How does the sarcolemma compare to a generic cell?

Back

The sarcolemma is the same as the cell membrane in a generic cell.

Front

What is the A band in a sarcomere?

Back

The A band is the region of the sarcomere that contains thick myosin filaments and overlaps with thin actin filaments.

Front

What role does tropomyosin play in muscle contraction?

Back

Tropomyosin is part of thin actin filaments and regulates muscle contraction by blocking the binding sites for myosin on actin.

Front

What is the function of the sarcoplasmic reticulum?

Back

The sarcoplasmic reticulum stores calcium necessary for muscle contraction.

Front

What are T-tubules?

Back

T-tubules are extensions of the sarcolemma that penetrate into the muscle cell, helping to transmit electrical impulses.

Front

What is the difference between the I band and the A band?

Back

The I band contains only thin actin filaments, while the A band contains both thick myosin and overlapping thin actin filaments.

Front

What is the H zone?

Back

The H zone is the central region of the A band where there is no overlap between thick and thin filaments.

Front

What is the role of calcium ions in muscle contraction?

Back

Calcium ions bind to troponin, causing tropomyosin to move and expose binding sites on actin for myosin, leading to muscle contraction.

Front

What is the function of myosin in muscle contraction?

Back

Myosin is a thick filament that interacts with actin to produce muscle contraction through cross-bridge cycling.