The Muscular System Muscles are bundles of cells

The Muscular System Muscles are bundles of cells and fibers. Muscles work in a very simple way. All they do is tighten up--that is, contract--and relax. You have two sets of muscles attached to many of your bones which allow them to move. There are 630 active muscles in your body and they act in groups. Muscles can only pull. They never push

Functions of the Muscular System Muscles convert chemical energy (energy stored in nutrients) into mechanical energy (the energy of movement). Muscles are often viewed as the "machines" of the body. They help move food from one organ to another, and carry out our physical movement. Muscles, where attached to bones or internal organs and blood vessels, are responsible for movement Nearly all movement in the body is the result of muscle contraction.

The Structure of a Muscle

How a Muscle Works Muscles work in pairs. When one muscle is contracting the other is relaxed.

Types of Muscles Cardiac Found in the heart involuntary Skeletal – Around bones voluntary Smooth – Controls bladder, arteries, digestive tract involuntary

Diseases of the Muscular System ABDOMINAL HERNIA - a rupture may occur in a weak place in the muscular abdominal wall. It is caused by bulging of the intestine through an opening in the abdominal cavity normally containing it. An inguinal hernia is in the groin area.

TETANUS - an infectious disease that is usually fatal. It is characterized by continuous spasms of the voluntary muscles. It is caused by the bacterium Clostridium tetani, which can enter the body through an open wound, puncture wound or burn. It can be prevented by getting periodic vaccinations.

MUSCULAR DYSTROPHY - not any one single disorder but a group of genetic diseases that is characterized by atrophy of skeletal muscle tissues. The cause remains unknown. Some forms are fatal. MD most often appears in childhood and the most common form of the disease is called Duchenne's MD where muscle atrophy is replaced by fat and fibrous tissue. Death is usually due to respiratory or cardiac muscle weakness.