Which term refers to the basic unit, structurally and functionally, of all the body's tissues?

• A. Cell
• B. Epithelium
• C. Tissue
• D. Organ

Answer: (A)

Cells are the basic unit, structurally and functionally, of all the body's tissues. Tissues are organized groups of cells that share a common origin and perform related functions, with a surrounding extracellular matrix that supports them and facilitates signaling. Epithelium is a specific type of tissue made of epithelial cells, so while it’s a tissue, it’s not the universal basic unit for all tissues. A tissue itself is a level built from cells and matrix, and an organ is made up of multiple tissues working together. Thus, the cell is the fundamental unit from which all tissues are formed and carry out their functions.