- A Dopamine deficiency in the substantia nigra region of the midbrain
- B Autoimmune attack on acetylcholine receptors at neuromuscular junction
- C Progressive loss of the myelin sheath surrounding central nervous system axons
- D Excess GABA accumulation occurring at inhibitory central nervous synapses
Correct answer: B. Autoimmune attack on acetylcholine receptors at neuromuscular junction
Explanation: Myasthenia gravis: autoimmune disease. Antibodies block or destroy acetylcholine receptors at NMJ. Causes muscle weakness, especially with repeated use.
Concept context
Brain, spinal cord, neurons, reflex arcs, and sense organs.