Columnar cells

General Information
Latin
Greek
TA98
TA2
FMA
Details
System	Epithelial tissue
Artery
Vein
Nerve
Lymphatic drainage
Precursor	Endoderm
Function	Absorption, secretion, protection
Identifiers
Clinical significance
Notes

Overview

Columnar cells are a type of epithelial cell characterized by their elongated, column-like shape. These cells are taller than they are wide, with nuclei that are typically located near the base of the cell. Columnar cells are primarily involved in absorption, secretion, and protection, and they are found lining various organs and structures within the body.

Structure

Columnar cells have a distinct morphology that allows them to perform their specialized functions. The apical surface of these cells often features microvilli or cilia, which increase the surface area for absorption or help in the movement of substances across the epithelial surface. The basal surface is attached to the basement membrane, which provides structural support and regulates the exchange of molecules between the epithelium and underlying tissues.

Nucleus

The nucleus of columnar cells is typically oval and located near the base of the cell. This positioning is advantageous for the cell's function, as it leaves more space in the apical region for organelles involved in secretion and absorption.

Cytoplasm

The cytoplasm of columnar cells contains numerous organelles, including endoplasmic reticulum, Golgi apparatus, and mitochondria, which are essential for the synthesis and transport of proteins and other molecules.

Types

Columnar cells can be classified into several types based on their location and function:

Simple Columnar Epithelium

Simple columnar epithelium consists of a single layer of columnar cells. This type of epithelium is found in areas where absorption and secretion are primary functions, such as the stomach, intestines, and gallbladder.

Pseudostratified Columnar Epithelium

Pseudostratified columnar epithelium appears to be stratified due to the varying positions of the nuclei, but it is actually a single layer of cells. This type is commonly found in the respiratory tract, where it is involved in the secretion of mucus and the movement of particles out of the airways.

Stratified Columnar Epithelium

Stratified columnar epithelium consists of multiple layers of cells, with only the top layer being columnar. This type is less common and is found in areas such as the male urethra and the ducts of some glands.

Functions

Columnar cells perform several vital functions depending on their location:

Absorption

In the small intestine, columnar cells with microvilli, known as enterocytes, are responsible for the absorption of nutrients. The microvilli increase the surface area, enhancing the cell's ability to absorb nutrients efficiently.

Secretion

Columnar cells in the stomach secrete mucus and digestive enzymes, aiding in the breakdown of food. In the respiratory tract, goblet cells, a type of columnar cell, secrete mucus to trap dust and pathogens.

Protection

Columnar cells provide a protective barrier against mechanical and chemical stress. In the gastrointestinal tract, they protect underlying tissues from acidic and enzymatic damage.

Clinical Significance

Columnar cells can undergo pathological changes that have clinical implications:

Metaplasia

In conditions such as Barrett's esophagus, the normal squamous epithelium of the esophagus is replaced by columnar epithelium, which can increase the risk of esophageal cancer.

Dysplasia

Dysplastic changes in columnar cells can be a precursor to cancer. For example, dysplasia in the columnar cells of the colon can lead to colorectal cancer.

Infections

Columnar cells can be affected by infections, such as Helicobacter pylori in the stomach, which can lead to gastritis and peptic ulcers.

See Also

• Epithelial tissue
• Microvilli
• Cilia
• Goblet cell

External Links

• [Link to relevant medical resources]

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