Sympathetic nervous system

Definition

The sympathetic nervous system (SNS) is a branch of the autonomic nervous system responsible for the body's 'fight or flight' response. It regulates physiological reactions such as heart rate, blood pressure, and energy mobilization in response to stress.

5 Must Know Facts For Your Next Test

1. The SNS increases heart rate and redirects blood flow to muscles during stressful situations.
2. It stimulates the release of glucose from energy stores for immediate use.
3. The SNS inhibits digestion by decreasing blood flow to the gastrointestinal tract.
4. It triggers the release of epinephrine (adrenaline) and norepinephrine from the adrenal glands.
5. Chronic activation of the SNS due to poor diet or stress can negatively impact neurological health.

Review Questions

• How does the sympathetic nervous system affect heart rate and blood pressure?
• What role does the SNS play in glucose metabolism during stress?
• Why is chronic activation of the sympathetic nervous system detrimental to neurological health?

Related terms

Parasympathetic Nervous System: The branch of the autonomic nervous system responsible for 'rest and digest' activities, counterbalancing the effects of the SNS.

Autonomic Nervous System: A part of the peripheral nervous system that controls involuntary body functions like heartbeat, digestion, and breathing.

Epinephrine: A hormone released by the adrenal glands that prepares the body for quick action during stressful situations by increasing heart rate and energy availability.