Types of epithelial cells (2023)

The epithelium can be defined as a highly organized cell complex, organized in layers and devoid of vital intercellular material, covering the internal and external surfaces of the body and the secretory organs, to name a few. Colloquially, epithelium is the layer of cells covering the body surface or line of body cavity. Both plants and animals have an epithelium, a type of cell wall. Epithelial cells, on the other hand, can be cuboid, flattened, or cylindrical in shape and stacked in one or more layers depending on their function. Epithelial tissue can be divided into two types: the covering and lining epithelium, which covers the outer and inner surfaces of most organs, and the glandular epithelium, which is responsible for forming most of the glands in the body.

What layers are epithelial cells made of and how do they work?

Simple epithelium and stratified epithelium are the two main epithelial layers, respectively.

Simple epithelium consists of a single layer of cells in direct contact with the basement membrane of the surrounding tissue. Simple epithelial tissue consists of columnar cells with an elongated shape.

These cells are often found in areas that need to be absorbed and filtered, such as the lining of most cavities in the body, such as the lining of a woman's ovary and the walls of arteries.

Stratified epithelium consists of multiple layers of cells that are present on the basement surface and remain attached to the basement membrane throughout their life cycle. On the other hand, they have no contact with the basement membrane. These batteries offer greater protection against external hazards, such as harmful toxins, than comparable batteries. Layered tissue is often found where protection is needed, such as the lining of the esophagus or the lining of the urethra and bladder.

How do epithelial cells differ from the rest of the body?

According to the morphology of the cells, the epithelium is divided into three parts:

squamous cells:

The squamous epithelium consists of flattened, scaly, irregular cells with discoid nuclei located centrally in the epithelium. Squamous epithelium is divided into two types: basal squamous epithelium and stratified squamous epithelium.

In short, the squamous epithelium is a barrier that allows substances to pass through by diffusion or filtration and secretes mucus. The main job of this epithelium is to protect the internal organs of the body from damage caused by wear and tear.

cube cells:

Cuboid epithelium consists of cuboidal cells with spherical nuclei in the center of the cells. Plain cuboid epithelium and stratified cuboidal epithelium are two forms of cuboidal epithelium found in the body. The main function of simple cuboidal cells is secretion and absorption, whereas the main function of stratified cuboidal epithelium is body protection.

Cylindrical battery:

Column cells are made up of taller and thinner cells that form a columnar structure. The nuclei of columnar cells are usually oval in shape, extending from top to bottom and lying close to the basal surface. There are three basic forms of columnar epithelium: simple columnar epithelium, pseudostratified columnar epithelium, and stratified columnar epithelium. The simple columnar epithelium is the most common type. Pseudostratified columnar cells secrete mucus and enzymes and also absorb nutrients, while simple columnar cells secrete mucus and transport mucus. Wear protection and mucus secretion are essential functions of the stratified columnar epithelium found throughout the body.

Epithelial tissue has multiple functions

By definition, epithelial tissue is a layer of cells tightly connected to form a continuous layer covering areas exposed to external substances. Following are some activities of epithelial tissue:

1. Protect subcutaneous tissue

2. Secretion is the process by which chemicals are released from cells.

3. Absorption occurs through the introduction of tiny molecules into cells.

Diffusion occurs when molecules migrate down their concentration gradient.

4. Use a sieve-like membrane to filter out tiny molecules, a process called filtration.

5. Receive through the senses

The cell structure of the epithelial tissue has the following interesting features:

In epithelial cells, the cells are separated by small amounts of extracellular material, with their integral membrane proteins projecting mainly into the tiny spaces between cells, which helps maintain the integrity of the epithelial cells.

1. Connective tissue support: All layers of epithelium in the body are supported by an underlying layer of connective tissue.

2. This feature suggests that adjacent epithelial cells are directly connected at many sites by specific cell junctions found in many epithelial cells.

3. Regeneration: Another remarkable property of epithelial tissue is its remarkable ability to regenerate after injury. While some epithelial cells are killed by friction, others are damaged by harmful elements in the external environment, such as bacteria, acids, and smoke. Their surface cells are easy to wipe off. However, when an epithelial cell receives enough nutrients, it is able to quickly replace cells lost through cell division, which are achieved through mitosis (cell division).

4. A free apical surface is present on all epithelial cells, connected by polarity to the basal surface. On the other hand, the function and structure of the upper and lower levels are distinguished by a property called polarity. The apical surface of the epithelium borders open spaces such as glands, ducts, cavities or hollow organs. In another aspect, the substrate surface is supported by a thin support sheet of the substrate layer that is an integral part of the base membrane.

finally

The most notable difference between epithelial and connective tissues are the cells that make up each tissue and their role. Squamous epithelium, cuboidal epithelium and columnar epithelium are the three cell types that make up the epithelial tissue. Cells in connective, cartilage, collagen, elastic, and adipose tissue are embedded in an indistinct matrix that surrounds them. Fibroblasts are the most common cell type, but there are also macrophages, mast cells, fat cells, plasma cells, white blood cells, and others. Body cavities, arteries, the digestive system, and other delicate internal organs are lined with epithelial tissue that serves various functions, aiding in elimination, transport, absorption, protection, and secretion. Connective tissue, on the other hand, is responsible for forming connections, supporting other tissues, and connecting other tissues.