Kkwar Myasthenia

Myasthenia is believe not to be hereditary or contagious.

Neuromuscular junction

Neuron and muscle are not connected to each other. There is a small gap between them. This is called neuromuscular junction. Neuron (from the brain or spinal cord) will passed action potential through axon of motor neuron to an axon terminal. Sodium ion (Na+) and calcium ion (K+) are higher concentration outside than from the inside of the muscle and neuron. Na+ and K+ want to go inside but blocked by these channels (voltage gated calcium channels and ligand gated cation channels). The negative charge turn to positive charge after the action potential is at the terminal. This causes the calcium voltage gated channel to open up and the Na+ flow inside. The inside of the terminal become more positive charge thus synaptic vesicle release acetylcholine (ACh) via exocytosis. The acetylcholine diffuse across the synaptic cleft. Acetylcholine will bind together with acetylcholine receptor (AChR) containing ligand gated cation channels on the muscle fiber causes the channel to open. The opened channel allowed Na+ to enter the muscle fiber while K+ exit muscle fiber. The process cause
Usually the immune system make antibodies to attack viruses, bacteria and germs. However in myasthenia gravis , the immune system for unknown reason see the acetylcholine as a foreign substances thus produce antibodies to block, attack and even destroy ACh. The acetylcholine unable to bind to the muscle thus cannot create muscle action potential to move or to contract muscle. When this happen the percentage of the muscle contraction decrease making those who suffered from it have trouble to move or contract their muscle at longer period of time or in continuous activity. However, it is not clearly known how someone get myasthenia