What does the sympathetic nervous system do? Its purpose?
Your sympathetic nervous system controls your “fight-or-flight” response. Danger or stress activates your sympathetic nervous system, which can cause several things to happen in your body. In response to danger or stress, your sympathetic nervous system may affect your:
- Eyes: Enlarge your pupils to let more light in and improve your vision.
- Heart: Increase your heart rate to improve the delivery of oxygen to other parts of your body.
- Lungs: Relax your airway muscles to improve oxygen delivery to your lungs.
- Digestive tract: Slow down your digestion so its energy is diverted to other areas of your body.
- Liver: Activate energy stores in your liver to an energy that can be used quickly.
These effects help you in situations where you might need to think or act quickly. They improve your eyesight, reflexes, endurance and strength. Your sympathetic nervous system also activates at times when your body’s under strain, like when you’re exercising or are sick.
Your sympathetic nervous system activity also affects your immune system and your body’s repair processes. These effects can help your body start repairs on an injury quickly if you get hurt.
Neurotransmitters
Your sympathetic nervous system uses chemicals called neurotransmitters to communicate. Specifically, these chemicals are norepinephrine, epinephrine and acetylcholine.
What’s the difference between the sympathetic and parasympathetic nervous systems?
Your sympathetic and parasympathetic nervous systems have opposite roles. While your sympathetic nervous system carries signals that put your body’s systems on alert, your parasympathetic carries signals that relax those systems.
The two systems work together to keep your body in balance. Your sympathetic nervous system takes the lead for as long as is necessary to get you through a period of danger. Then, your parasympathetic nervous system steps in and returns things to normal.
