How does the muscular system work?

The muscular system is responsible for the movement of the human body. It is made up of over 600 muscles, which are attached to bones by tendons. The muscles work together to provide movement, support, and heat production.

The basic unit of a muscle is a muscle fiber, which is composed of myofibrils. Myofibrils are made up of sarcomeres, which are the functional unit of muscle contraction. When a muscle fiber receives a signal from the nervous system, the sarcomeres contract, causing the muscle to shorten and produce movement.

There are three types of muscles in the body: skeletal, smooth, and cardiac. Skeletal muscles are attached to bones and are responsible for voluntary movements, such as walking and lifting. Smooth muscles are found in the walls of internal organs and blood vessels, and are responsible for involuntary movements, such as the contraction of the stomach and blood vessels. Cardiac muscles are found in the heart, and are responsible for the heartbeat.

The muscular system requires energy to function, which is supplied by the body's metabolic processes. When a muscle contracts, it uses energy in the form of ATP (adenosine triphosphate). ATP is produced through a process called cellular respiration, which requires oxygen and glucose.