Which tissue type forms the protective covering on organ surfaces and lines many cavities?

Which tissue type forms the protective covering on organ surfaces and lines many cavities?

• A. Epithelial tissue
• B. Muscular tissue
• C. Nervous tissue
• D. Connective tissue

Answer: (A)

Epithelial tissue forms protective coverings on organ surfaces and lines many cavities. It sits on a basement membrane, is usually avascular, and consists of tightly packed cells that create continuous sheets acting as barriers and selective gates. Depending on location and function, it can be arranged in one layer (simple) for absorption and diffusion or in multiple layers (stratified) for protection. The shapes—squamous, cuboidal, and columnar—fit different roles, such as stratified squamous protecting skin and oral cavity, or simple squamous lining blood vessels and air sacs for easy diffusion. Epithelial tissue also forms glands that secrete mucus and enzymes. By contrast, muscular tissue generates movement, nervous tissue transmits signals, and connective tissue provides support and connection.

Epithelial tissue forms protective coverings on organ surfaces and lines many cavities. It sits on a basement membrane, is usually avascular, and consists of tightly packed cells that create continuous sheets acting as barriers and selective gates. Depending on location and function, it can be arranged in one layer (simple) for absorption and diffusion or in multiple layers (stratified) for protection. The shapes—squamous, cuboidal, and columnar—fit different roles, such as stratified squamous protecting skin and oral cavity, or simple squamous lining blood vessels and air sacs for easy diffusion. Epithelial tissue also forms glands that secrete mucus and enzymes. By contrast, muscular tissue generates movement, nervous tissue transmits signals, and connective tissue provides support and connection.