Body structures refer to the various parts that make up an organism, including cells, tissues, organs, and systems. Each structure has a specific function that contributes to the overall health and operation of the body. For example, muscles enable movement, while bones provide support and protection for vital organs. In humans, body structures are organized into systems, such as the skeletal system, muscular system, and nervous system. These systems work together to maintain homeostasis and allow the body to respond to internal and external stimuli. Understanding body structures is essential for fields like anatomy and medicine.