Final answer:
The main function of the nervous system is to help the body react to internal and external stimuli through sensation, integration, and response.
Step-by-step explanation:
The main function of the nervous system is to help the body react to internal and external stimuli. It does this through sensation, integration, and response. Sensation involves receiving information about the environment, integration combines sensory perceptions with memories and emotions, and response generates appropriate motor responses.
As a claim, evidence, and reasoning:
Claim: The main function of the nervous system is to help the body react to internal and external stimuli.
Evidence: The nervous system is involved in sensation, which is the process of receiving information about the environment. It is also involved in integration, which combines sensory perceptions with memories and emotions. And finally, the nervous system is involved in responses, generating appropriate motor responses to stimuli.
Reasoning: By performing these three functions, the nervous system allows the body to adapt and respond to changes in the internal and external environment. This helps to maintain homeostasis and ensure the survival of the organism.