Marker. 1  Noun. A line of credit extended by a casino or cardroom. 2  Noun. A small object placed on top of a player's hand for the purpose of preventing it from being mucked or fouled. 3  Noun. A plastic device used to denote who is in the dealer's position.
Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction -- the place where nerve cells connect with the muscles they control.
Causes of Myasthenia Gravis. It is caused due to failure in the linkage between the muscles and the nerves. The nerves in your body release chemicals called neurotransmitters to form a communication link with your muscles. The muscle cells consist of receptor sites.yasthenia gravis makes your immune system generate antibodies which either block or damage the various receptor sites that your muscles have. As you end up having lesser receptor sites, your muscles too get lesser signals from the nerve making them weak.