The term smooth muscle refers to a muscle of the human body that is part of a involuntary muscle group. These muscles are extremely important to help the body perform a variety of crucial tasks, and can be found in many parts of the body. The walls of hollow organs are the primary place that smooth muscles can be found.
Where You Can Find Smooth Muscles
- Walls of blood vessels
- Walls of stomach
- In the aorta (tunica media layer)
- Iris of the eye
- Gastrointestinal Tract
- Respiratory Tract
- Small arteries
- Reproductive tracts (both genders)
- Glomeruli of the Kidneys (called mesangial cells)
- Arrector pili of the skin
- Ciliary muscle
- Bile duct
The functions of smooth muscles depend on where they are found in the body. The functions of smooth muscles are extremely crucial to the effectiveness of each organ with which the muscles are involved.
Functions of Smooth Muscles
- The smooth muscle in the uterus helps a woman to push out her baby.
- In the bladder, smooth muscle helps to push out urine.
- Smooth muscle determines the flow of blood in the arteries.
- Smooth muscles move food through the digestive tract.
- In one's eye the pupillary sphincter muscles is responsible for shrinking the size of the pupil.
- In arteries, smooth muscle movements maintain the arteries' diameter.
- Smooth muscle regulates air flow in lungs.
- Smooth muscle help sperm to move along the reproductive tract.
- Smooth muscle in the lungs helps the airways to expand and contract as necessary
- Skin stands on end when piloerector muscles contract.
- To prevent urination during ejaculation by men, the sphincter muscle constricts.
- The tunica dartos is a smooth muscle that contracts or expands to regulate temperature of the testicles.
- Smooth muscles in arteries and veins are largely responsible for regulation of blood pressure.
Understanding Smooth Muscles
There are three types of muscles in the body: Smooth muscles, cardiac muscles, and skeletal muscles. Smooth muscles are unique in their largely involuntary response, and in their structure. Smooth muscles have a much stronger ability to contract than skeletal muscles, and are able to maintain contraction longer.
There are two types of smooth muscles:
- Visceral smooth muscle - All cells work together at the same time as one unit.
- Multi-unit smooth muscle - Cells can act and function independently of the others.
Now you see lots of smooth muscle examples, know where these muscles are in your own body and understand the roles of these different muscles.