What is the nervous system triggered to respond to?

Stimuli

The nervous system is triggered to respond to stimuli. Stimuli are changes in the environment that the body detects. There are many different types of stimuli, including:

* Physical stimuli: These stimuli include changes in temperature, light, sound, and pressure.

* Chemical stimuli: These stimuli include changes in the chemical composition of the blood, such as changes in pH or glucose levels.

* Biological stimuli: These stimuli include the presence of toxins, bacteria, or viruses.

When the body detects a stimulus, it sends a signal to the nervous system. The nervous system then triggers a response that is appropriate to the stimulus. For example, if the body detects a painful stimulus, the nervous system will trigger a response that causes the body to move away from the source of pain.