Glandular Epithelium and Gland Classification

Glandular Epithelium

• Glandular epithelium can be classified into two types: unicellular and multicellular.
• Unicellular glands consist of isolated glandular cells, such as goblet cells in the alimentary canal.
• Multicellular glands consist of a cluster of cells, such as the salivary gland.

Gland Classification

• Glands can be classified based on their secretion method into two types: exocrine and endocrine.
• Exocrine glands secrete mucus, saliva, earwax, oil, milk, digestive enzymes, and other cell products via ducts or tubes.
• Endocrine glands lack ducts and secrete hormones directly into the fluid surrounding the gland.

Compound Epithelium

• Compound epithelium consists of multiple layers of cells.
• Its primary function is to provide protection against chemical and mechanical stresses.
• It covers the dry surface of the skin, the moist surface of the buccal cavity, pharynx, and the inner lining of ducts of salivary glands and pancreatic ducts.

Cell Junctions

• Cell junctions hold epithelial cells together with minimal intercellular material.
• Three types of cell junctions provide structural and functional links between cells: tight junctions, adhering junctions, and gap junctions.
• Tight junctions prevent substances from leaking across a tissue.
• Adhering junctions cement neighboring cells together.
• Gap junctions facilitate cell communication by connecting the cytoplasm of adjacent cells, allowing rapid transfer of ions, small molecules, and sometimes large molecules.

Connective Tissue

• Connective tissue is the most abundant and widely distributed tissue in complex animals.
• Its primary function is to link and support other tissues and organs in the body.
• Connective tissue ranges from soft connective tissues to specialized types.