Essays on Neuromuscular Junction

Muscle contraction is a very important activity that enables an organism perform various bodily movements and flexible actions, in response to nerve stimuli. Muscle fibers are multinucleated long cylindrical cells that have an outer membrane called sarcolemma, and are mainly composed of contractile elements called myofibrils (Dougherty, 2016). Myofibrils are made up of repeating units called sarcomeres. Sarcomeres in turn are composed of (thin) actin and (thick) myosin protein filaments called myofilaments (Dougherty, 2016). The muscle fiber structure and organization is shown in Fig 1.

Contraction Mechanism – Sliding Filament Theory

According to the sliding filament theory, during contraction myosin filaments remain constant in length, ...

Myasthenia gravis

Myasthenia gravis is an autoimmune disease characterized by the production of antibodies, which are directed against nicotinic acetylcholine postsynaptic receptors located at the neuromuscular junction. This leads to a gradual decrease in the number of acetylcholine receptors at the postsynaptic neuromuscular junction. There are two different variants of myasthenia gravis, which include the ocular myasthenia gravis and the generalized form of myasthenia gravis. The result of the reduction in the number of acetylcholine receptors lead to a concomitant reduction in the muscle strength (Paul, 2000). However, there is recovery of the muscle strength resting it for some time (Kulkantrakon & Jarungkiatkul, 2010), ( ...