Question

People with myasthenia gravis have a deficiency of

A. titin molecules.
B. troponin molecules.
C. acetylcholine receptors
D. sarcomeres.

Answer 1

People with myasthenia gravis have a deficiency of acetylcholine receptors. This autoimmune disease leads to antibodies blocking these receptors, resulting in muscle weakness and fatigue.

Step-by-step explanation:

People with myasthenia gravis have a deficiency of C. acetylcholine receptors. Myasthenia gravis is an autoimmune disease that primarily affects the neuromuscular junction. In this condition, the body's own immune system produces antibodies that block or destroy the acetylcholine receptors on the muscle cells, which are necessary for the transmission of nerve impulses that trigger muscle contractions. This leads to the characteristic muscle weakness and fatigue experienced by individuals with this disorder.

The other options provided, such as titin molecules, troponin molecules, and sarcomeres, are not directly related to the neuromuscular deficits observed in myasthenia gravis. Instead, these components are involved in the structure and regulation of muscle contraction but do not play a role in the specific pathology of myasthenia gravis, which is an impairment of the acetylcholine receptor function at the neuromuscular junction.

Answer 2

In myasthenia gravis, the deficiency is of acetylcholine receptors due to the production of antibodies that block these receptors, inhibiting normal muscle contraction. The correct answer is C. acetylcholine receptors.

Step-by-step explanation:

People with myasthenia gravis have a deficiency of acetylcholine receptors on the muscle cells. Myasthenia gravis is an autoimmune disorder where the immune system produces antibodies that block or destroy these receptors at the neuromuscular junction, which inhibits muscle contraction, leading to weakness and fatigue.

Unlike options A, B, and D (titin molecules, troponin molecules, and sarcomeres, respectively), which are structural components of muscle fibers, acetylcholine receptors are crucial for receiving signals that lead to muscle contraction. The impairment in neuromuscular transmission is primarily because the body's antibodies bind to these receptors, preventing acetylcholine from binding and thus interfering with normal muscle function.

Acetylcholine is necessary for muscle contraction because it binds to receptors on the muscle fiber, initiating a cascade of events that result in muscle fibers contracting. When acetylcholine receptors are compromised, as in myasthenia gravis, this process is disrupted, leading to the characteristic symptoms of the disease. Therefore, the correct option in the final answer reflecting the deficiency seen in individuals with myasthenia gravis is C. acetylcholine receptors.