Each cell (fiber) of a muscle comprises of various myofibrils that usually run parallel in a cell. Myofibrils serve as the contractile elements of the cells of a muscle while every myofibril comprises of sarcomeres chains. A myofibril comprises of bands including both light as well as dark. As for the I-bands, they are the light ones whereas the A-bands are the dark ones. These are usually visible striations observed in skeletal muscle. The myofibril banding pattern results from filaments referred to as myofilaments (Exploring Nature, 2017) . In the event of the thick filaments, they play the role of extending the A-bands thick filaments whereas the thin filaments usually extend past the I-band toward the A-band. When the muscle is relaxed, the A-bands inside features a light stripe referred to as the H-zone. The H-zone is normally lighter since the thin and thick filaments do not usually overlap. In the case of the M-line, it is situated at each H-zone’s center at a section whereby the think filaments usually link. The myofibril’s region that exists between the two Z-lines is referred to as sarcomere that serves as the smallest contractile unit of the cell of a muscle (MJC, 2017) .
Neuromuscular Junction Structure and Role
A neuromuscular junction refers to the link that prevails in the middle of the skeletal muscle together with the motor neuron. The nerve cells facilitate the communication that usually exists between two. Owing to communication that exists here, the muscle is capable of relaxing or contracting. In the event of a motor neuron, it plays the role of leading the skeletal muscle to contract through stimulating it. The space or gap that exists between the skeletal muscle cell as well as the motor neuron is referred to as a synapse. The synapse, especially one prevailing between motor neuron as well as muscle cell is referred to as the neuromuscular junction. The impulse that travels between the spaces leads the contraction of the muscle to occur (New Health Advisor, 2017) .
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References
Exploring Nature. (2017). A closer look at skeletal muscles fibers (cells) and myofibrils. Retrieved from https://www.exploringnature.org/graphics/anatomy/muscle_fibrils_myofibrils.pdf
MJC. (2017). Skeletal muscle physiology. Retrieved from http://droualb.faculty.mjc.edu/Course%20Materials/Elementary%20Anatomy%20and%20Physiology%2050/Lecture%20outlines/skeletal_muscle_physiology.htm
New Health Advisor. (2017). Neuromuscular junction structure and functions. Retrieved from http://www.newhealthadvisor.com/Neuromuscular-Junction.html
