What is defined as a structure in the body that is composed of different kinds of tissue?

An organ is defined as a structure in the body that is composed of different kinds of tissue working together to perform specific functions. For instance, the heart is an organ made up of cardiac muscle tissue, connective tissue, and epithelial tissue, all contributing to its overall ability to pump blood throughout the body. This distinction is crucial because it highlights the complexity of biological structures and emphasizes that organs are more than just a single type of tissue; they involve multiple tissue types interacting synergistically.

In contrast, tissue refers to a group of cells that work together to carry out a specific function but does not encompass the variety of different tissue types found in an organ. A cell is the most basic unit of life and can function independently but does not represent a structure composed of multiple types of tissues. A system refers to a group of organs that work together to perform complex functions within the body, but it does not describe a singular structure made up of various tissues.