Question

Which of the following tissues participate in secretion, absorption and excretion?

• A. Squamous epithelium
• B. Cuboidal epithelium
• C. Columnar epithelium
• D. Pseudostratified epithelium

Answer 1

The correct option is B Cuboidal epithelium

Squamous epithelium is a single layer of thin flattened cells with irregular boundaries. They are also known as tessellated epithelium or pavement epithelium. They are found in alveoli, lymph vessels and blood vessels (endothelium), endocardium of heart, lining of the Bowman’s capsule. They form a diffusion boundary.
Cuboidal epithelium appears cuboidal in vertical section and polygonal in surface view. They participate in secretion, absorption and excretion. They are found in the duct of salivary glands, thyroid follicles present in the thyroid gland, in the proximal convoluted tubule of the nephrons. Microvilli increase the surface area for enhanced absorption. They are also referred to as brush-border epithelium.
Columnar epithelial cells appear column-like in vertical sections. Nucleus is usually located near the base. They are found in the inner lining of the small intestine. Microvilli are present on the apical surface which increase the surface area for absorption.
Pseudostratified epithelium are single layered but appear to be double layered. This is due to the different size of cells. The nuclei also lie at different levels. They can be ciliated or non ciliated. Ciliated epithelium is found in the trachea. Non-ciliated are found in the auditory tube.