Muscular System - General
Muscle makes up 40% of body weight and like the skeleton is important for the body for posture, walking, facial expressions and other movements of the body. With the skeletal system, muscle is attached to the bones to support and keep the bones together from falling apart and keep full function. The metabolism produced in muscles also make the heat in order to maintain the proper body temperature.
There are 3 types of muscles:
Cardiac muscle helps the heart maintain its heart rate and is the reason for a heart rate. Also this muscle is only found in the heart in which makes up the ventricles and atria, although this muscle isn't controlled by conscious thoughts for its contractions.
Skeletal muscle focus mainly to flex and relax in order to support movement in a joint. Tendons attach tissue to bone to connect them together, just like how ligaments connect bone to bone. Tendons can be strengthened by physical exercise in order to have a stronger attachment. Nervous signals are sent to the muscle cells in order to maintain muscle tones, when a muscle is partly contracted, in order to keep body posture and preparation for any physical activity such as sports. Each contraction that this muscle makes produces heat from the energy made in a muscle contraction. To avoid the overheating of the body, the sweat glands activated in order to cool down the body and muscles make contractions when body is cold in order to provide heat to warm the body.
Smooth muscles are found and make up the tissue of organs in the body such as the stomach, blood vessels, glands, etc. Unlike the cardiac and skeletal muscle, the smooth muscle makes wave like contractions in order to aid in transporting and digesting food. Besides the heart, any muscle that contracts without any conscious thought is done by smooth muscles.
Full information can be found from this source: A.D.A.M. "Muscular System Information." Muscular System Information. A.D.A.M., 2001. Web. 14 Dec. 2014. <http://www.walgreens.com/adamHtml/bodyguides/reftext/html/musc_sys_fin.html>.