This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Which receptors are blocked in Myasthenia Gravis. 
Select and explain. 
A. Ach receptors, B. Calcium receptors, C. Sodium receptors, D. Opioid receptors
A: Ach receptors
Answer: A: Ach receptors 
Explanation: Ref. Guyton. 13th edition. Page.  96
Myasthenia gravis is an autoimmune disease characterized by autoantibodies against the acetylcholine (ACh) receptor of the neuromuscular junction, result- ing in muscular weakness predominantly affecting the facial muscles. Females are affected more frequently than males.

Extra ocular muscle weakness may lead to ptosis and diplopia; the weakness worsens with repeated contractions.
Respiratory muscle involvement may lead to death. 

There is an association with thymic hyperplasia and thymomas.
Treatment is anticholinesterase agents, steroids, and thymectomy.