What is the largest body system in the human body?

The integumentary system is the largest body system in the human body, primarily because it includes the skin, which is the body's largest organ. The integumentary system serves several vital functions, including protecting the body from external harm, regulating temperature, and providing a barrier to pathogens. It contains various types of tissues and structures, such as hair, nails, and glands, that contribute to its overall size and complexity.

In comparison, although the muscular system consists of all the muscles in the body and plays a crucial role in movement, it does not encompass as much surface area as the integumentary system. The nervous system, while intricate and essential for communication throughout the body, is made up of nerve tissues and cells and does not have the same expansive physical coverage as the skin. The circulatory system, which includes the heart and blood vessels, is vital for transporting blood and nutrients but is also not comparable in size to the full extent of the integumentary system. Therefore, the integumentary system stands out as the largest body system due to its extensive structure and multiple functions.