Smooth muscle cells
Smooth Muscle Cells
Smooth muscle cells (pronunciation: /smuːθ ˈmʌskəl sɛlz/) are a type of muscle cell that make up the smooth muscle tissue in the body. They are non-striated, involuntary muscles found in the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, and blood vessels. Unlike skeletal muscle cells, smooth muscle cells are not under conscious control.
Etymology
The term "smooth muscle cell" derives from their appearance in histological sections, where these cells appear smooth and uniform, unlike the striated appearance of skeletal muscle cells. The term "muscle" comes from the Latin musculus, meaning "little mouse", possibly because of the shape of certain muscles or the way certain muscles move.
Structure
Smooth muscle cells are spindle-shaped and contain a single, centrally located nucleus. They are smaller than skeletal muscle cells and have a much slower rate of contraction. The cells are arranged in sheets or layers, with the long axes of the cells aligned. This arrangement allows for coordinated, wave-like contractions, known as peristalsis, that move substances through the organs.
Function
The primary function of smooth muscle cells is to maintain organ dimensions and control the flow of substances through the organs. They do this by contracting and relaxing in response to various stimuli. For example, in the blood vessels, smooth muscle cells contract to constrict the vessels and increase blood pressure, or relax to dilate the vessels and decrease blood pressure.
Related Terms
- Myocyte: A type of cell found in muscle tissue.
- Peristalsis: The wave-like contractions of smooth muscle that move substances through the organs.
- Vasoconstriction: The constriction of blood vessels, which increases blood pressure.
- Vasodilation: The dilation of blood vessels, which decreases blood pressure.
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