The muscular system in the body is like the basis for a working machine. Every lever and pulley of a machine runs by machinery and the body is just as dependent on the muscular system. Walking, moving, sitting, running, even blinking, swallowing and coughing all use the muscular system during each of these essential movements. The muscular system works without us knowing it during every move we make, even pumping blood through our bodies.
Three Types of Muscles
The muscles in a body fall into three main categories: skeletal, smooth and cardiac.
There are over 650 skeletal muscles in the human body. There is some dissent among medical professionals about the total number of muscles in the body. They are constantly being discovered and many cannot agree on the number. But these skeletal muscles are attached to the skeletal system and make it possible for the body to move; they are called voluntary muscles because of one's ability to use them or not. They are made up of tissue fibers and look striated (striped or lined) because thread-like protein called filaments are within the muscle cells.
Smooth muscles are involuntary, they do what they do without action or any conscious thought. These muscles are in the stomach lining the walls and in the intestines, They are in the veins and arteries and in many hollow organs. These muscles help with the digestive process in the stomach and are controlled by the nervous system in the body. These muscles do not have filaments in them and therefore have no striations.
Cardiac muscles are found only in the heart. They are like smooth muscle in that they are controlled by the body's nervous system. These muscles form the myocardium, which are the thick muscles forming the walls of the heart. These muscles are strong, ropey and twisted together inside the heart to pump the blood through the body.
Muscles at Work
Muscles cannot push, they are only able to pull. Why? Because two muscles need to team up to produce a movement. When one muscle contracts, the other flexes. This is how the muscles are arranged in the body, so that flexing and contraction can make up all our movements. Even with a body at rest, muscles are still contracting and flexing. At the very core of it all, the brain and nervous system are in charge of the muscular system.