Muscular and Endocrine Systems - Essay Example

"Muscular and Endocrine Systems" is an engrossing example of a paper on the musculoskeletal system.

The structure and function of a sarcomere

The most crucial component in muscle is muscle fibril. It is composed of the basic unit known as the sarcomere (RCN, 2014). The sarcomere, on the other hand, comprises of several things. The most vital components in the sarcomere are the actin and myosin, which are proteins (RCN, 2014). Actin appears as the thin filaments while the myosin appears as thick filaments (RCN, 2014).  The two proteins overlap each other in the sarcomere. The two filaments play a significant role in the movement of muscles through the process of contraction. The movement occurs due to the contractile nature of the proteins. Z-line occurs at the end of each sarcomere. The actin is attached to the Z line (RCN, 2014). Likewise, the myosin is connected to the z-line. However, the myosin is attached in the central part of the sarcomere by the M-line (RCN, 2014). There is also an H zone in the sarcomere.  This is part of the A-band where the proteins do not overlap.

The process of muscle contraction

The contraction of muscle requires stimulation by a nervous system. This takes place as the nerve impulse moves along the motor neurons. As the impulse reaches the axon terminal, the acetylcholine is discharged to the postsynaptic membrane on the muscle fiber (RCN, 2014). This causes the diffusion of sodium ions through the opening of channels (RCN, 2014). This leads to the generation of an action potential in the fiber upon reaching the threshold. The generated action potential then moves along the fiber. The fiber is activated, and this prompts myosin head to bind to actin (RCN, 2014). As a result, this leads to a conformation change that draws the thin filament a short distance past the thick filament with the use of energy as ATP. The arrival of action potential also causes the release of calcium ions in the tubules (RCN, 2014). The ions diffuse in alternatively in the two filaments and bind to troponin on the actin (RCN, 2014). This enhances the interaction of proteins and the sarcomere contracts (RCN, 2014).