What is defined as a body part made of tissues performing a special function?

An organ is defined as a body part made of tissues that work together to perform a specific function within the body. Each organ is composed of multiple types of tissues that collaborate to carry out particular tasks essential for the body's overall functioning. For example, the heart is an organ made up of muscle tissue, connective tissue, and epithelial tissue, all of which contribute to its role in pumping blood throughout the body.

Understanding the hierarchical organization of biological structures is crucial; it starts at the cellular level—where individual cells serve as the basic unit of life—moving up to tissues, which are groups of similar cells that perform a collective function. These tissues then combine to form organs, which can be grouped into systems that work synergistically to maintain homeostasis and support life. Thus, recognizing an organ as a complex structure built from tissues underscores the vital interconnections in biological systems.