1. The nervous system is a network of nerve cells and tissues that carries messages to and from the brain and spinal cord to all parts of the body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events.

2. The endocrine system is a network of glands that produce and release hormones into the bloodstream. Hormones travel throughout the body and control many different bodily functions, including growth, metabolism, and reproduction.