Respuesta :
Columnar epithelium consists of a single layer of cells in which all cells rest directly on the basement membrane and all cells reach the apical surface.
What is a epithelial tissue?
Epithelial tissue has a free surface, which faces either a body fluid or the outside environment and thus provides a covering or a lining for some parts of the body.
There are two types of epithelial tissues namely :
- Simple epithelium: Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities, ducts, and tubes.
- Compound epithelium: The compound epithelium consists of two or more cell layers and has protective function as it does in our skin.
Simple epithelium is further divided into three types, they are;
- The squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary.
- The cuboidal epithelium is composed of a single layer of cube-like cells. This is commonly found in ducts of glands and tubular parts of nephrons in kidneys and its main functions are secretion and absorption.
- The columnar epithelium is composed of a single layer of tall and slender cells. Their nuclei are located at the base. Free surface may have microvilli. They are found in the lining of stomach and intestine and help in secretion and absorption.
To learn more about epithelial tissues: https://brainly.com/question/13404204
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