Final answer:
An organ is a separate body structure composed of two or more different types of tissues. Examples of organs include the heart, brain, and stomach. Each organ performs one or more specific physiological functions.
Step-by-step explanation:
A separate body structure composed of cells of two or more different tissues is referred to as an organ. In the biological hierarchy, cells group together to form tissues which then form organs. Each organ in the body, such as the heart, brain or stomach, is composed of two or more types of tissues that work together to perform specific functions. For instance, the heart contains muscular tissue that allows it to contract and pump blood, but it also includes nervous tissue to maintain its rhythm and connective tissue to add structure and resilience.
Hence, this level of organization concurs to the overall structure and function of the human body. An organ system, such as the circulatory, digestive or nervous system, is a further level of organization that involves multiple organs working in harmony to achieve major physiological functions.
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