Epithelial tissue

Definition

Epithelial tissue is a type of tissue that forms the protective outer layer of the body and lines internal organs and cavities. This tissue serves crucial roles in absorption, secretion, sensation, and protection, making it integral to various biological systems. Epithelial cells are tightly packed with minimal extracellular matrix, which helps create barriers and interfaces between different environments within the body.

5 Must Know Facts For Your Next Test

1. Epithelial tissue is classified based on the number of layers (simple or stratified) and the shape of its cells (squamous, cuboidal, or columnar).
2. It plays a key role in processes like filtration in the kidneys, gas exchange in the lungs, and secretion of substances from glands.
3. Epithelial cells are avascular, meaning they lack blood vessels; instead, they receive nutrients through diffusion from underlying connective tissues.
4. This tissue has a high regeneration capacity, allowing for quick repair and replacement after injury.
5. Epithelial tissue can form specialized structures such as cilia for movement or microvilli for increased surface area in absorption.

Review Questions

• How does the structure of epithelial tissue relate to its functions in the body?
  • The structure of epithelial tissue is closely tied to its functions. For example, the tightly packed cells with minimal extracellular matrix provide a barrier that protects underlying tissues while allowing selective permeability for substances to pass through. Simple squamous epithelium facilitates rapid diffusion, as seen in alveoli of lungs. In contrast, stratified epithelium provides more protection against mechanical stress, making it suitable for areas like the skin.
• Discuss the significance of the basement membrane in supporting epithelial tissue.
  • The basement membrane plays a crucial role in supporting epithelial tissue by providing structural integrity and anchoring epithelial cells to the underlying connective tissue. It acts as a barrier that separates epithelial cells from connective tissue while facilitating nutrient exchange through diffusion. Additionally, it influences cell behavior, including proliferation and differentiation, which is essential for maintaining healthy epithelial function and facilitating repair mechanisms.
• Evaluate how abnormalities in epithelial tissue can lead to diseases and disorders.
  • Abnormalities in epithelial tissue can have significant consequences for overall health and can lead to various diseases. For example, uncontrolled growth of epithelial cells can result in cancers such as carcinoma. Furthermore, disruptions in normal functions, such as impaired secretion or absorption due to damaged epithelial layers, can lead to conditions like cystic fibrosis or inflammatory bowel disease. Understanding these connections highlights the importance of epithelial integrity in maintaining homeostasis within biological systems.

Related terms

Connective Tissue: A type of tissue that supports, binds together, and protects other tissues and organs in the body.

Basement Membrane: A thin, fibrous layer that separates epithelial tissue from underlying connective tissue, providing support and anchoring cells.

Glandular Epithelium: A specialized form of epithelial tissue that forms glands responsible for secretion of hormones, enzymes, and other substances.