Sympathetic nervous system

Definition

The sympathetic nervous system (SNS) is a part of the autonomic nervous system responsible for the body's 'fight or flight' response. It prepares the body to react to stressful situations by increasing heart rate, dilating pupils, and inhibiting digestion.

5 Must Know Facts For Your Next Test

1. The SNS uses neurotransmitters like norepinephrine and epinephrine to transmit signals.
2. SNS activation leads to physiological changes such as increased heart rate and blood pressure.
3. It works in opposition to the parasympathetic nervous system which promotes 'rest and digest'.
4. SNS nerve fibers originate from the thoracic and lumbar regions of the spinal cord.
5. Chronic activation of the SNS can lead to health issues such as hypertension.

Review Questions

• What are the primary functions of the sympathetic nervous system?
• Which neurotransmitters are primarily associated with sympathetic nervous system activity?
• How does the sympathetic nervous system interact with other parts of the autonomic nervous system?

Related terms

Autonomic Nervous System: The division of the peripheral nervous system that controls involuntary body functions.

Parasympathetic Nervous System: Part of the autonomic nervous system that promotes rest and conservation of energy.

Norepinephrine: A neurotransmitter involved in arousal and stress responses, often used by the sympathetic nervous system.