The human body is organized at multiple levels, from cells to tissues to organs to organ systems. Cells combine to form tissues like epithelial, connective, nervous, and muscle tissue. Groups of tissues working together form organs like the eye. Organ systems are groups of organs that work together, such as the nervous system. The body maintains homeostasis through feedback inhibition, where a stimulus triggers a response that counteracts the stimulus, keeping conditions stable. Examples include regulating temperature and blood glucose levels. The liver plays an important role in homeostasis by processing toxins, storing and releasing glucose, and regulating blood sugar levels.