Merck Manual

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Divisions of the Autonomic Nervous System

Divisions of the Autonomic Nervous System

Division

Effects

Sympathetic

Increases the following:

  • Heart rate and force of heart contractions

  • Release of energy stored in the liver

  • The speed at which energy is used to perform body functions while a person is at rest (basal metabolic rate)

  • Muscle strength

Widens the airways to make breathing easier

Causes sweaty palms

Decreases functions that are less important in an emergency (such as digestion and urination)

Controls the release of semen (ejaculation)

Parasympathetic

Stimulates the digestive tract to process food and eliminate wastes (in bowel movements)

Slows the heart rate

Reduces blood pressure

Controls erections