1. Define the nervous system. What is its primary function in the human body?

The nervous system is a complex network of nerves and cells, known as neurons, that transmit signals between different parts of the body. It is essentially the body's electrical wiring and is divided into two parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and spinal cord, while the PNS consists of all the nerves that branch out from the brain and spinal cord and extend to other parts of the body including muscles and organs.

The primary function of the nervous system is to send signals from one cell to others, or from one part of the body to others. It is responsible for coordinating all of the body's activities. It does this by transmitting signals very rapidly across long distances. It allows us to perceive, comprehend, and respond to the world around us. It also helps control the body's internal environment by regulating temperature, blood pressure, and body pH, among other things.