What is the smallest unit of the human body?

The smallest unit of the human body is the cell. Cells are the fundamental building blocks of all living organisms, including humans. They perform essential functions such as energy production, metabolism, and reproduction, making them vital for the overall function of tissues, organs, and systems within the body.

While tissues are made up of groups of similar cells that work together to perform a specific function, and organs consist of different types of tissues collaborating to carry out complex functions, the cell is the primary structural and functional unit from which these larger structures are formed.

Micro-organisms, although they can be smaller than cells, refer to microscopic life forms such as bacteria, viruses, and fungi, which are not part of the human body itself but can exist within or on it. They are distinct entities and do not contribute to the structure of the human body in the way that cells do.