Which option correctly presents the accurate statements?
Statement 1: The light band comprises actin filaments and lacks myosin filaments.
Statement 2: The endoplasmic reticulum functions as a storage site for calcium ions.
Statement 3: The dark band consists of myosin filaments and lacks actin filaments.
Statement 4: A sarcomere is a region between two neighboring M-lines positioned at the midpoint of the A-band.
Statements 1 and 2 are correct.
Statements 2 and 3 are correct.
Statements 3 and 4 are correct.
Statements 1 and 4 are correct.
Statement 1 accurately describes that the light band (also known as the I-band) consists of actin filaments but lacks myosin filaments. This distinction in filament composition contributes to the light appearance of the I-band in a sarcomere.
Statement 2 is also correct, as the endoplasmic reticulum (ER) functions as a storage site for calcium ions. The ER plays a vital role in regulating calcium levels within muscle fibers, releasing calcium ions during muscle contraction. Therefore, Option 1 is the correct answer.