There are three types of muscle tissue: Cardiac, skeletal, and visceral (smooth).
1. Cardiac Muscle: Found only in the heart, cardiac muscle is responsible for pumping blood throughout the body. While hormones and signals from the brain adjust the rate of contraction, cardiac muscle stimulates itself to contract making it an involuntary muscle.
2. Skeletal Muscle: These muscles always connect to the skeleton in at least one place. Most skeletal muscles are attached to two bones across a joint, so the muscle serves to move parts of those bones closer to each other. Skeletal muscle is the only voluntary muscle tissue in the human body. Every physical action that a person consciously performs (e.g. speaking or running) requires skeletal muscle.
3. Visceral (Smooth) Muscle: Visceral muscle is found inside organs like the stomach, intestines, and blood vessels. Visceral muscle makes organs contract to move substances through. Visceral muscle is controlled by the unconscious part of the brain, making them involuntary muscles. The term “smooth muscle” is often used to describe visceral muscle because it has a smooth, uniform appearance when viewed under a microscope.
Functions of the muscular System
1. The muscular system creates movement
The main function of the muscular system is movement. Muscles are the only tissue in the body that has the ability to contract and therefore move other parts of the body.
2. The maintenance of posture and body position
The muscles responsible for the body’s posture have the greatest endurance of all muscles. They hold up the body throughout the day without becoming tired.
3. It protects the organs
The abdominal muscles and the muscles of the lower back help protect the vital organs of the body. Bones do not protect the organs in the abdominal cavity like the rib cage protects the heart and lungs.
4. The skeletal muscles pull (lever) on the bones
This maintains the bone density. As we age the lever action of muscles on the bones is one of the most important contributors to maintaining bone density. The participation in resistance exercise (Pilates and weights) has become increasingly important to achieve this result.
5. The cardiac muscle pumps blood
In the human body, the heart is responsible for receiving blood back from your muscles, pumping it into the lunges then pumping it out into the arteries to supply the entire body.
6. Visceral muscle aids digestion
The visceral muscles of the stomach and intestines work to process the food we ingest. The involuntary contractions in the stomach and intestines aid in digestion and in moving food along the digestive tract, ultimately directing indigestible substances to the rectum.
7. Visceral muscles ensures blood flow
There are visceral muscles in the walls of the blood vessels. When the heart contracts, the arteries expand to accept blood. The visceral muscles in your arteries contract to push the blood throughout the blood vessel systems in the body. This is why when plaque builds up on the inside of the walls of the arteries, the arteries harden and the muscles in your arteries do not contract properly.
8. The generation of body heat
As a result of the high metabolic rate of contracting muscle, our muscular system produces a great deal of waste heat. Many small muscle contractions within the body produce our natural body heat. When we exert ourselves more than normal, the extra muscle contractions lead to a rise in body temperature and eventually to perspiration.
Our bodies work hard don’t they!
By Simon Ayling
Chevron Island Physio