Simply put, muscles are responsible for movement and to produce force. When stimulated, it allows body parts to move, whether it be to shuffle our legs to walk, expand our lungs to breathe or even to send food through the digestive system so that we can provide sustenance to the body.

Muscle is essentially contractile tissue. As one of the four primary or basic tissue types, muscle tissue is comprised of cells that are dominated by filaments of actin and myosin. When muscle cells are stimulated appropriately they contract by these proteins, which slide past each other and become “engaged”. Once the muscle has completed the contraction, it returns to its original relaxed position with the help of adenosine triphosphate (ATP), a molecule that not only separates the two proteins, but also reacts with myosin to provide the energy for a muscle cell to contract. This is the process that occurs every time we move. Muscle tissue can only lengthen when other muscle tissue contracts.

There are three different types of muscle tissue in humans: skeletal, cardiac and smooth.

Skeletal Muscle
Comprised of cells that very long and striated. It is voluntary, meaning it can be consciously controlled by the nervous system and is found attached to the bone structure of the human body (skeleton). Skeletal muscle makes up about 40% of the mass of the average adult body.

Cardiac Muscle
Comprised of tissue that is striated and branched. Found only in the heart and is mainly involuntary.

Smooth Muscle
Comprised of cells that are tapered at the ends. Found in all organ systems, in the larger blood vessels to control the distribution of blood. Because of their location, smooth muscle is also known as visceral muscle. It is involuntary.