Characteristics of Epithelial Tissue

Characteristics of Epithelial Tissue

• Epithelial tissue lines the body's surfaces, internally and externally, and forms glands.
• Two main types: membranous epithelium and glandular epithelium.
• Membranous epithelium covers external surfaces and lines internal cavities, organs, tubes, and passageways.
• Glandular epithelium is specialized for the production and secretion of substances like sweat, stomach acids, mucus, and hormones.

Key Characteristics

• Cellularity: Epithelial tissue consists entirely of cells.
• Polarity: Cells exhibit differences in structure and function between the apical (top) and basal (bottom) surfaces.
• Basal Surface: The part of the cell sitting on the basement membrane is known as the basal surface.
• Apical Surface: The part of the cell facing the lumen (e.g., intestine) or external body (e.g., skin) is the apical surface.
• Attachment: The basal surface is anchored to the underlying connective tissue via the basal lamina or basement membrane.
• Avascular: Epithelial tissue lacks its own blood supply and is nourished by diffusion from nearby capillaries.

Nutrient Supply

• Nutrients for epithelial tissue are obtained through diffusion from capillaries located in the underlying connective tissue.

Regeneration

• Epithelial tissue exhibits high regenerative capacity, which is crucial for repairing injuries like cuts or bruises.

Functions of Epithelial Tissue

• Provides protection against mechanical injury, pathogens, and chemical exposure.
• Controls permeability, facilitating selective absorption and secretion.
• Contains specialized cells that provide sensations, contributing to sensory perception.
• Produces secretions that serve various functions in the body.

Examples and Additional Facts

• An example of epithelial tissue is the skin.
• Epithelial tissue has a rich nerve supply, which is important for sensory functions and responses.