The muscular system is the network of tissues that help controls movement throughout the body using contraction and relaxation of different muscles. This system is divided into two classes, skeletal (voluntary) and smooth (involuntary). Skeletal muscles are known as voluntary because the mind allows a person to control their movement, such as flexing their bicep or raising their hand to answer a question in class. The skeletal muscle is connected …show more content…
For example, when you think of moving your leg using your quadriceps, the brain directs a signal down a nerve cell to your quadriceps muscle to contract. The amount of muscle being contracted depends on the signal that the nerve sent.
A muscle is consisted of a lot of conjoined cells called fibers. Imagine these fibers as elongated cylinders. In comparison to other cells in the body, muscle fibers are by far fairly larger. Fibers length measures from 1 to 40 microns and 10 to 1000 microns wide. To imagine how big these fibers are we can say that a thread of hair is about 100 microns wide and a cell is 10 microns wide.
Muscle fibers contain numerous amounts of myofibrils, which is a basic rod-like unit of muscle proteins. A muscle cell is able to contract because of these proteins. These proteins comprise of two different types of filaments that are longitudinal to the fiber, and are organized into hexagonal designs. There are both thick and thin filaments, in which every thick filament there is 6 thin filaments.. Both filaments are connected to an alternative component known as the Z-line, which is perpendicular to the fibers long side. A side note to remember is that the myofibril that runs from one Z-line to another is called a sarcomere. Down the Z-line is a small tube called the transverse or T-tubule. A membrane system called the sarcoplasmic reticulum stores and releases calcium ions that trigger muscle contraction within the