Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.

In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.

Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.

A healthy muscle will have the most contractile force when __________.

Which of the following proteins does not play a functional role in creating the force-tension curve of muscle contraction?

Which two proteins are the major components of myofibrils, allowing for muscle fiber contraction?

During a muscular contraction, which of the following elements maintains constant length?

Which of the following is true about the organization of actin filaments and myosin in sarcomeres?

A researcher observes a sarcomere through a microscope. He notices that a single myosin filament is forty micrometers long and that a single actin filament is fifty micrometers long. What can the researcher conclude from this information?

Which of the following is true of actin and myosin filaments?

What is a sarcomere?

Which of the following changes length during sarcomere contraction?

I. Thick filaments

II. Thin filaments

III. H zone

Which of the following is true about sarcomeres?