Skelatal Muscles - Essay Example

In turn, the abundance of Ca2+ ions allows binding with troponin, thus loosening up the tropomyosin that, during relaxation, twirls around the actin covering specifically the binding sites of myosin (http://www.unmc.edu/physiology/Mann/mann14.html. 2008). The next question is, where does ATP and Ca2+ needed for muscle contraction come from? It all starts from a motor neuron, which sends signals from the brain to muscles through neurotransmitters. The motor neurons release acetylcholine, which upon binding to cholinergic receptors on a myofibril, causing mobilization of ions and subsequent depolarization that results to the release of Ca2+ from the sarcoplasmic reticulum to the cytoplasm (http://www.unmc.edu/physiology/Mann/mann14.html. 2008).

Because of the many mechanisms discussed above, various conditions cause imbalance and subsequent abnormality to muscle contraction. Convulsion is a homeostatic imbalance state that causes the neurons to fire repeatedly and involuntarily. Thus, it causes, among others, the involuntary movement of skeletal muscles. On the other hand, in conditions such as stroke and multiple sclerosis, the neurotransmitters are not released from the neuromuscular junction, thus causing muscle weakness. In myotonia congenita, the chloride channel ions needed to put back the myofibrils into its hyperpolarized state after contraction are not expressed, leading to delayed relaxation.

Metubine is a compound that prevents and reduces the intensity of muscle contractions. Molecularly, it is a competitor of acetylcholine in binding to cholinergic receptors, which upon activation initiates muscle contraction (NCBI, 2010). Knowing its mechanism of action provides valuable information in addressing health conditions such as convulsion. Knowing the mechanisms of muscular contraction is important to nurses as it provides great insights on the type of drugs to be given in