What system is responsible for regulating tissue fluids and combating disease?

The lymphatic system is primarily responsible for regulating tissue fluids and combating disease. It plays a crucial role in maintaining fluid balance within the body's tissues by collecting excess interstitial fluid and returning it to the bloodstream. This function helps to prevent edema, which is the excessive accumulation of fluid in tissues.

Moreover, the lymphatic system is integral to the immune response. It transports lymph, a fluid that contains immune cells such as lymphocytes, and transports them to lymph nodes where they can identify and respond to pathogens, such as bacteria and viruses. This is essential for the body's defense mechanisms, as it helps to filter harmful substances from the lymph fluid and enables the production of antibodies that help combat infections.

The other systems listed contribute to the body's overall function but do not specifically focus on the regulation of tissue fluids and disease response in the same way the lymphatic system does. For instance, while the circulatory system is responsible for blood flow and nutrient transport, and the endocrine system regulates bodily functions through hormones, neither directly addresses the management of tissue fluid balance and immune response as the lymphatic system does. The nervous system is primarily involved in communication and control of bodily functions, but it does not play a direct role in fluid management or disease combatting.