Muscles in the human body perform several important functions. The primary function of muscles is movement, both voluntary and involuntary. Another function is to support the body, thereby helping to maintain posture. Healthy strong muscles also stabilize the body's many joints and determine overall body strength. An additional function of muscles in the human body is to generate heat as a byproduct of other processes.
The most obvious, primary function of muscles in the human body is movement. One type of movement is voluntary. This involves a conscious effort on the part of the individual and examples include walking, bending, twisting, and lifting. It also includes fine motor movements such as writing or playing an instrument. The type of muscle usually responsible for voluntary movement is called skeletal; it is striated muscle that has a banded or striped appearance under a microscope. Skeletal muscles are attached to the bones and produce locomotion by contracting, or tightening, and relaxing.
The other type of movement is involuntary; it's controlled by the brain and occurs automatically. Examples of involuntary movement include breathing, the movement of food through the digestive system, and the beating of the heart. These movements occur without any effort from the individual; many of them sustain life and continue even if the person is asleep or unconscious. Signals from the brain control these involuntary actions, and the muscles that perform these movements are often smooth in nature, except for the striated cardiac muscle.
Another function of the muscles in the human body is support. The skeletal muscles are constantly working to support the body and help to maintain posture whether a person is sitting or standing. The muscles also support, stabilize, and strengthen the joints by holding the bones in proper position, especially in areas where the parts of a joint do not fit together closely such as the shoulders and hips. The skeletal muscles also are vital in determining overall body strength and the ability to perform various physical tasks. Maintaining strong muscles is helpful for general health and well-being.
The muscles in the human body are also important for the maintenance of the correct body temperature. They actually generate heat as a byproduct of other processes. As the muscles consume nutrients to provide power for movement, some of the energy creates heat. It is estimated as much as 75 percent of the energy produced escapes as heat. Considering that skeletal muscle comprises a large percentage of total body mass, the amount of heat generated is significant and plays an important role in maintaining a healthy temperature.
