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 for stressful or emergency situations by increasing heart rate, dilating pupils, and inhibiting digestion.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system activates the adrenal glands to release adrenaline.
2. It increases heart rate and blood pressure to prepare muscles for sudden action.
3. Sympathetic nerve fibers originate in the thoracic and lumbar regions of the spinal cord.
4. It works antagonistically with the parasympathetic nervous system to maintain homeostasis.
5. Activation of this system results in dilation of airways in the lungs to improve oxygen intake.

Review Questions

• What is the primary function of the sympathetic nervous system?
• How does the sympathetic nervous system affect heart rate and blood pressure?
• Where do sympathetic nerve fibers originate within the spinal cord?

Related terms

Autonomic Nervous System: A division of the peripheral nervous system that regulates involuntary physiological functions.

Parasympathetic Nervous System: The part of the autonomic nervous system responsible for 'rest and digest' activities, working antagonistically with the sympathetic nervous system.

Adrenaline: A hormone released by adrenal glands during stress, enhancing physical performance by increasing heart rate and energy levels.