NEET Biology: Disorders of muscular and skeletal system-Myasthenia gravis Practice Questions

Correct answer: A — Neuromuscular junction

Myasthenia gravis is a disorder affecting the neuromuscular junction (NMJ), where the signal transmission between the motor neuron and the muscle fiber is impaired due to autoantibodies blocking or interfering with acetylcholine receptors.

Correct answer: C — Acetylcholine receptors

The autoimmune attack targets the receptors responsible for binding acetylcholine, which are the acetylcholine receptors (AChRs).

Correct answer: A — Fluctuating and fatigable weakness

Patients with MG experience weakness that worsens with repeated use and fatigues over time, which is characteristic of neuromuscular junction disorders.

Correct answer: A — Neuromuscular junction

Myasthenia gravis is an autoimmune disorder where antibodies attack the receptors at the neuromuscular junction, leading to impaired signal transmission.

Correct answer: D — Postsynaptic membrane of the muscle fiber

Myasthenia gravis is an autoimmune disease that attacks the postsynaptic receptors (nicotinic acetylcholine receptors) at the neuromuscular junction, causing weakness in muscle contraction.

Correct answer: C — Muscular system

Since MG involves defects in the transmission between nerve and muscle, the primary system affected is the muscular system (neuromuscular transmission).

Correct answer: A — Binding of acetylcholine to the receptor

The weakness stems from the reduced number or function of the acetylcholine receptors, impairing the ability of the nerve impulse to properly trigger muscle contraction.

Correct answer: A — Neuromuscular transmission

The core issue in Myasthenia Gravis is impaired neuromuscular transmission—the inability of the nerve signal (ACh) to effectively bind to and activate the postsynaptic receptors, leading to fatigue with use.

Correct answer: A — Fatigue and weakness

The defining clinical feature of Myasthenia Gravis is fluctuating muscle weakness and fatigue, which is due to insufficient signal transmission to the muscle fibers.

Correct answer: B — Autoimmune disorder

Myasthenia gravis is an autoimmune disease where the body's immune system mistakenly attacks its own tissues, specifically the neuromuscular junction.

Correct answer: B — Nicotinic acetylcholine receptors

The autoimmune process targets and attacks the postsynaptic acetylcholine receptors (AChRs), leading to insufficient signal transmission across the neuromuscular junction.

Correct answer: B — Fluctuating and fatigable

Muscle weakness in MG is episodic and worsens with repeated use (fatigability) due to the failure of sustained signal transmission.

Correct answer: C — Generalized muscle fatigue

While MG causes specific weakness, generalized muscle fatigue is a common non-specific symptom reported by patients experiencing neuromuscular dysfunction.

Correct answer: C — Nicotinic acetylcholine receptors (AChRs)

In Myasthenia gravis, autoantibodies primarily target the acetylcholine receptors (AChRs) located on the postsynaptic membrane of the muscle fiber.

Correct answer: C — Synaptic transmission at the neuromuscular junction

Myasthenia gravis is characterized by impaired neuromuscular transmission, specifically affecting the receptors and transmission at the neuromuscular junction.