1. Sympathetic and Parasympathetic Nervous System
SLO: – Differentiating between the functions of the sympathetic and parasympathetic system

2. Both Systems:
Most organs are supplied by both sympathetic and parasympathetic fibers, and the two systems generally have opposite effects.

3. The Sympathetic System
Tends to act as an accelerator for those organs needed to meet a stressful situation.
It promotes the fight or flight response
Stimulated by the 4 “Es”
Emergency
Excitement
Embarrassment
Exercise

4. Effects of the Sympathetic System:
Increase in the rate and force of heart contractions
Increase in blood pressure due partly to the more effective heartbeat and partly to constriction of small arteries everywhere except the brain
Dilation of blood vessels to skeletal muscles, bringing more blood to these tissues
Dilation of the bronchial tubes to allow more oxygen to enter and more carbon dioxide to leave
Stimulation of the central portion of the adrenal gland

5. Effects of the Sympathetic System:
Increase in basal metabolic rate
Dilation of the eye’s pupil and increase in distance focusing ability

6. Sympathetic System – Only what’s necessary!
The sympathetic system also acts as a brake on those systems not directly involved in the stress response, such as the urinary and digestive systems
(example: difficulty eating when angry)

7. Parasympathetic System
The parasympathetic system normally acts as a balance for the sympathetic system once a crisis has passed
The “Rest and Digest” system
Causes:
Constriction of pupils
Slowing of heart rate
Constriction of bronchial tubes
Stimulates activities to maintain homeostasis
Promotes the formation and release of urine and the activity of the digestive system