Nowadays, more and more people are starting to be aware of the seriousness of the obesity. Thus, people start to go to the gym workout, try to lose weight while building up the muscle to have them look fitter. Muscle, which came from muscular system, it responsible every movement of the body. Skeletal muscle is one of the muscle tissue, and it is the only voluntary muscle tissue in the human body. Each time we perform physical action, the muscle contraction will occur and produce tension that our body need for physical action, such as talk or excise. In this paper, I will be discussing about how molecular mechanism occur in the muscle during contraction and the role of ATP plays during the muscle contraction and relationship to the rigor mortis.
Muscle contraction is the process to develop tension within the muscle tissue. Two of the key protein involve in the process of muscle contraction are the myosin and actin. When myosin and actin interact, the shape of muscle cell will be change. The theory that scientists come up with is the sliding filament theory, according to the A Dictionary of biology, it states that:
“A proposed mechanism of muscle contraction in which the actin and myosin filaments of striated muscle slide over each other to shorten the length of the muscle fibers (see sarcomere). Myosin-binding sites on the actin filaments are exposed when calcium ions bind to troponin molecules in these filaments. This allows bridges to form between actin and myosin, which requires ATP as an energy source. Hydrolysis of ATP in the heads of the myosin molecules causes the heads to change shape and bind to the actin filaments. The release of ADP from the myosin heads causes a further change in shape and generates mechanical energy that causes the actin and myosin filaments to slide over one another” (Oxford University Press).
In another word, when contraction occur, actin filament will slide over myosin filament, this movement of protein will cause a shape change of the muscle cell, which produce tension and movement. Since skeletal muscles are voluntary cells, our brain will continuously be sending the commands and get stimulated by the nerve impulses. The signal that is being sending out from brain is action potential, which is “stimulation of the cell by neurotransmitters or by sensory receptor cells partially opens channel-shaped protein molecules in the membrane. Sodium diffuses into the cell, shifting that part of the membrane toward a less-negative polarization” (propagated potential).
There are three types of muscle contraction, depend on the muscle, and reason for the contraction. isotonic
“Sliding filament theory.” Oxfordreference.com.proxy.library.csi.cuny.edu, Oxford University Press, 2008, www.oxfordreference.com.proxy.library.csi.cuny.edu/view/10.1093/acref/9780199204625.001.0001/acref-9780199204625-e-4101.
“Propagated potential.” Academic.eb.com.proxy.library.csi.cuny.edu, academic.eb.com.proxy.library.csi.cuny.edu/levels/collegiate/article/action-potential/3611.