Human organs are specialized structures within the body that perform specific functions essential for survival. They work together in systems, such as the circulatory system, which includes the heart and blood vessels, to transport oxygen and nutrients. Other vital organs include the lungs, which facilitate breathing, and the liver, which helps in detoxification and metabolism. Each organ is made up of tissues that are composed of cells, and they vary in size and shape. For example, the brain is responsible for processing information and controlling bodily functions, while the kidneys filter waste from the blood. Together, these organs maintain the body's overall health and functionality.