Physical Therapy Assistant Practice Exam

Which of the following statements correctly describes myasthenia gravis?

1. It is an autoimmune disorder that weakens voluntary muscles.

2. It primarily affects the heart function.

3. It results from genetic predisposition.

4. It causes uncontrollable muscle contractions.

The correct answer is: It is an autoimmune disorder that weakens voluntary muscles.

Myasthenia gravis is indeed correctly defined as an autoimmune disorder that weakens voluntary muscles. In this condition, the immune system mistakenly produces antibodies that block or destroy the receptors for acetylcholine, a neurotransmitter essential for muscle contraction at the neuromuscular junction. As a result, the communication between nerves and muscles is impaired, leading to muscle weakness and fatigue, particularly during periods of activity. This hallmark of the disorder is understood through its symptoms, which often include weakness in the eye muscles, facial and throat muscles, and can progress to other voluntary muscle groups. Thus, the nature of myasthenia gravis is characterized by its impact on voluntary muscle function rather than other bodily systems. In contrast, the other choices do not accurately reflect the nature of myasthenia gravis. While some muscle-related conditions might involve genetic factors or result in uncontrolled muscle contractions, they do not describe myasthenia gravis specifically. Additionally, this disorder does not primarily affect heart function, nor is it categorized as a genetic disorder. Instead, it has clear autoimmune characteristics, affirming choice A as the most accurate description.