MGSLG. (2020). Module 2 Unit 5

Location and functions of the Autonomic Nervous System

Autonomic nervous system

  • The autonomic nervous system (ANS) controls the heart rate, breathing, digestion and gland functions e.g. salivary glands secreting saliva
  • The autonomic nervous system has TWO branches
  • The sympathetic branch prepares the body for energy-expending, stressful, or emergency situations
  • The parasympathetic branch is active under ordinary, restful conditions
  • The two systems have an opposite effect: one stimulates, the other inhibits i.e. each organ in the body is innervated by the sympathetic nerve and parasympathetic nerve
  • This is known as double innervation
  • E.g. the sympathetic nerve causes the iris to dilate and the parasympathetic nerve causes the iris to constrict.


Sympathetic branch

Parasympathetic branch

1.       Increases heart rate

1.       Decreases heart rate

2.       Relaxes walls of the bladder

2.   Contracts wall of the bladder

3.       Dilates pupils

3.   Constricts pupils

4.       Constricts many arteries

4.   Dilates arteries

5.       Increases blood pressure

5.   Decreases  blood pressure


Last modified: Thursday, 18 March 2021, 1:03 PM