Final answer:
Myasthenia gravis is an autoimmune disorder that causes muscle weakness and fatigue. It can result in drooping eyelids (ptosis) and overall muscle weakness. The disease progresses to affect muscles in other parts of the body.
Step-by-step explanation:
Myasthenia gravis is an autoimmune disorder characterized by muscle weakness and fatigue. It occurs when antibodies block the nicotinic acetylcholine receptors on the motor endplate of the neuromuscular junction. This can lead to symptoms such as drooping eyelids (ptosis) and overall muscle weakness. The disease progresses to affect muscles in other parts of the body, making swallowing, chewing, and speaking difficult.