Sympathetic nervous system

Definition

The sympathetic nervous system is a part of the autonomic nervous system responsible for the body's 'fight or flight' response. It prepares the body to respond to stress or emergencies by increasing heart rate, dilating airways, and mobilizing energy stores.

5 Must Know Facts For Your Next Test

1. It uses neurotransmitters like norepinephrine and epinephrine to transmit signals.
2. Activation of the sympathetic nervous system leads to pupil dilation and increased blood flow to muscles.
3. It inhibits non-essential functions such as digestion during stressful situations.
4. Beta receptors in the heart are primarily targeted by sympathetic stimulation to increase cardiac output.
5. Sympathetic nerves originate from the thoracic and lumbar regions of the spinal cord.

Review Questions

• What are the primary neurotransmitters used by the sympathetic nervous system?
• How does activation of the sympathetic nervous system affect heart rate and digestion?
• From which regions of the spinal cord do sympathetic nerves originate?

Related terms

Autonomic Nervous System: A division of the peripheral nervous system that controls involuntary bodily functions.

Parasympathetic Nervous System: Part of the autonomic nervous system responsible for 'rest and digest' activities.

Norepinephrine: A neurotransmitter involved in arousal and alertness, used predominantly by the sympathetic nervous system.