Tissue Epithelium

A type of tissue that lines the surfaces and cavities of organs throughout the body.

This tissue type is characterized by its ability to regenerate quickly, making it essential for repairing damaged areas.

Epithelia can be classified into two main categories: epithelium of lining (Covering Epithelium) and glandular epithelium.

Epithelium of lining: Lines surfaces and cavities, forms protective layers.
Glandular epithelium: Specialized for secretion, forms glands producing substances like hormones, enzymes, and mucus.

Glandular epithelium can be classified into exocrine glands (ducts) and endocrine glands (release into bloodstream).

This tissue's ability to regenerate quickly, making it essential for repairing damaged areas.

Epithelial cells are tightly packed together, forming continuous sheets that can be one or several layers thick.

It serves as a protective barrier, regulating the exchange of substances between different areas and providing structural support.

- Type of glandular epithelium
- Secrete hormones directly into the bloodstream
- Lack ducts, release products into surrounding capillaries
- Regulate physiological processes like metabolism, growth, and reproduction
- Examples: pituitary gland, thyroid gland, adrenal glands

- Structure of ducts: simple, compound
- Mode of secretion: merocrine (exocytosis), holocrine (entire cell disintegrates)
- Examples: merocrine glands, holocrine glands

- Shape of cells: squamous, cuboidal, columnar
- Number of cell layers: simple, stratified
- Presence of specialized structures: cilia or microvilli
- Examples: squamous epithelium, cuboidal epithelium, columnar epithelium

Specialized for secretion, forming glands throughout the body that release substances such as hormones, enzymes, and mucus. It includes exocrine glands (ducts) and endocrine glands (direct secretion into the bloodstream).

It lines surfaces and cavities, forming protective layers covering external and internal surfaces. It includes the skin, digestive tract, respiratory tract, and blood vessels.

Covering of external surfaces (e.g., Skin)
Lining of internal surfaces (e.g., Pleura)
Protection (e.g., Mouth)
Absorption (e.g., Small intestine)
Filtration (e.g., Kidney)
Secretion (e.g., Pancreatic cells)
Sensation (e.g., Taste buds)