Epithelial cells safeguard the body. These are tightly packed acting as a barrier between the exterior and the interior. Additionally, as they are able to stretch they induce movements, maintain homeostasis and some of these cells are receptors collecting signals. They are found lining various body structures, helping in absorbing and transporting nutrients to be used up. Some other epithelial cells synthesize and release enzymes in the stomach. Furthermore, some of these release hormones into the blood vessels, are involved in breast milk production, mucus secretion in the nose and more. They perform a range of functions depending on the location where they are found and shape.
Majorly, epithelial cells can be categorized into the following –
- Squamous epithelial cells
- Ciliated columnar cells
- Columnar epithelial cells
- Cuboidal epithelial cells
In this article, we learn briefly about Squamous Epithelial cells, its functions, location and structure.
What Are Squamous Epithelial Cells?
Squamous epithelial cells are large, flattened cells filled with cytoplasm possessing a small round nucleus at the centre. They are flat and have an irregularly round shape. The term “squamous” is derived from the comparison of the cells to the fish’s scales. These cells are typically found lining the surfaces requiring a smooth flow of fluid as seen in the blood vessels. They are also found lining the areas requiring a very thin surface for molecules enabling passage such as air sacs in the lungs. Generally, the width of these cells is greater than their height.
Squamous Epithelial cells – Location
In the respiratory system, the Simple Squamous epithelial cells are found in the lungs and are a part of the circulatory system by the lining they render to the capillaries. Their presence in the alveolar epithelium enables simple passive diffusion. Stratified squamous epithelial cells are found lining the mouth, skin and the vagina. Specialized squamous epithelium forms the lining of the body cavities, blood vessels and the pericardium.
Squamous Epithelial cells – Structure
These cells have the appearance of flat and thin plates which may appear polygonal from the top view. Cells are densely packed rendering a low-friction and smooth surface over which easy movement of fluids takes place. Nucleus takes its shape from the form of the cell helping to detect the type of epithelium. The nuclei is almost oval-shaped and flattened due to the structure and the shape of the cell.
Squamous Epithelial cells – Function
The outline of the cells is slightly irregular wherein the cells fit in forming a lining or covering. The simple epithelia (cells arranged in a single layer) promote the diffusion in tissues namely the regions of gas exchange in the lungs and the exchange of the wastes and nutrients at the blood capillaries.
Protection and Secretion
Renders a smooth, frictionless surface where secretion takes place. The epithelium is involved somewhat with protecting the underlying tissues against toxins, invasion of foreign particles and less intense physical trauma. Protection in extreme mechanically stressed regions cannot be rendered. Since there are no blood vessels in the epithelium tissues, bleeding due to abrasion is prevented.
Some of these cells produce mucus, acting as a lubricating agent against frictions. Secretion of biologically active molecules is brought about by the mesothelium of various parts.
Transportation and Absorption
Role of these cells is critical in the sites where transportation and absorption occurs. In the lining of cavities and vessels, these cells check the passage of particles into the tissues underneath. Across the surface of this tissue, various physiological processes such as diffusion, osmosis and filtration occur.
Processes such as oxygen diffusion, blood filtration in the Bowman’s capsule of the kidneys and diffusion of carbon dioxide between blood vessels and organs are carried out via these cells. The simple squamous epithelium forming the mesothelium promotes the active transport of fluid through pinocytosis alongside promoting the movement of viscera.
This was a brief description of Squamous epithelial cells, its structure, location and functions. Visit us at NEET BYJU’S for more interesting articles.