What two body systems are the most important in maintaining homeostasis?

The two body systems that are most important in maintaining homeostasis are the nervous system and the endocrine system. The nervous system helps to monitor and respond to changes in the external and internal environment through nerve impulses, while the endocrine system helps to regulate bodily functions through the production and release of hormones. Together, these two systems work together to help maintain a stable internal environment despite changes in the external environment.