Which body system helps in fluid balance and fights against infections?

The immune system is essential for fighting against infections and plays a crucial role in fluid balance within the body. It is responsible for identifying and eliminating pathogens, such as bacteria and viruses, that can cause disease. This system is made up of various cells, tissues, and organs, including lymph nodes, the spleen, and white blood cells, which work together to protect the body.

In terms of fluid balance, the immune system helps to regulate the movement of fluids through the lymphatic system, which is a part of the larger circulatory system. This system collects and returns excess fluid from tissues to the bloodstream, preventing edema and ensuring that the body's cells receive the nutrients they need while also removing waste.

The other body systems listed have different primary functions: the endocrine system is mainly involved in hormone regulation, the reproductive system focuses on reproduction and sexual health, and the respiratory system is responsible for gas exchange, primarily oxygen intake and carbon dioxide expulsion. While these systems may have indirect roles in overall health, the immune system is specifically designed to combat infections and maintain fluid balance.