Muscular System
There are more than 600 muscles in the human body ranging from tiny muscles such as those in the face and fingers, to large muscles in the legs. The muscular system functions to:
- Provide movement
- Produce heat
- Posture
- Balance
- Movement of food through the digestive tract
- Breathing
There are three categories of muscles found in the human body
- Skeletal muscle (also called striated muscle)
- Smooth muscle (non-striated muscle)
- Cardiac muscle
Skeletal muscle
Skeletal muscle provides movement for the body. This movement produces heat which helps to regulate body temperature. Skeletal muscle is made up of long muscle cells (fibers), also called striations. The fibers are attached to bones by tendons. Movement is produced when these muscles contract or relax. At least two muscles are needed to obtain movement. One must contract while the other corresponding muscle relaxes. Skeletal muscle is considered voluntary muscle since movement requires conscious thought.
Smooth muscle
Smooth muscle is considered involuntary muscle because a person cannot consciously control its contractions. Contractions of smooth muscle are controlled by the autonomic nervous system. Smooth muscle mainly comprises the organ systems, and the circulatory system, and is responsible for the movement of food through the digestive system, and helps movement in the circulatory system by dilating or constricting blood vessels.
Cardiac muscle
Cardiac muscle is only found within heart. It is involuntary muscle; however the contraction of the heart is regulated by the sinus node which is indirectly influenced by the medulla oblongata located within the brain. Cardiac muscle works with smooth muscle to move blood throughout the body.
Disorders of the muscular system include
- Myopathies
- Chronic fatigue syndrome
- Muscular dystrophy
- Rhabdomyolysis