Skeletal Muscle Essay

The muscular system is one of the most complex organ systems in the body, and it is imperative to the body’s survival, as it serves many significant functions, including movement, protection, posture, and heat production just to name a few. The muscular system has three types of muscle: skeletal, smooth, and cardiac. However, the main focus will be on the skeletal muscles and how they contract, as well as fatigue and respond to changes in temperature. In terms of the anatomy of the skeletal muscle, it is connected to bones by tendons, enabling movement. The muscle has layers around its main body: the fascia and the epimysium. A muscle is made up of many fascicles, bundles of myofibers (muscle cell) surrounded by perimysium. Each myofibers is made up of myofibril, the contacting organelle inside the
First, an electrical impulse or action potential from the central nervous system triggers a muscle contraction. When this happens, acetylcholine (ACH) serves as a neurotransmitter, sending the signal to the neuromuscular junction. The impulse is then propagated down the sarcolemma and through the t-tubules. As this signal travels down the t-tubules, Calcium (Ca2+) is released from the sarcoplasmic reticulum to the sarcomere, one unit of contraction with actin and myosin and z-lines on each side. Calcium binds to the troponin protein, located on the actin filament. This allows tropomyosin to move, exposing the myosin head binding sites on actin. When the myosin heads bind to actin, this is known as the cross bridge. ADP and Pi molecules are released, causing myosin to pull on actin. This movement is known as the power stroke. To stop the contraction, ATP binds to the myosin head, and myosin detaches from actin, stopping the contraction. After the impulse or action potential ceases, Calcium returns to the sarcoplasmic reticulum and tropomyosin return, covering myosin binding sites on