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Autonomic nervous system facts for kids

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The autonomic nervous system
Blue = parasympathetic
Red = sympathetic

The autonomic nervous system (ANS) controls the conditions inside the body. It is sometimes called the 'visceral nervous system' or 'involuntary nervous system'. The ANS is part of the peripheral nervous system.

The Autonomic nervous system controls all automatic actions. That means most of its activities are done without the person having conscious control over them. The person usually cannot feel what the ANS is doing. However, some of the ANS's activities work together with the conscious mind, like breathing.

The Autonomic nervous system controls many different things, like heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils and the discharge of urine.

There are two different sections within the ANS:

Function

The Autonomic Nervous System
Function of the autonomic nervous system

Sympathetic and parasympathetic divisions typically function in opposition to each other. Some typical actions of the sympathetic and parasympathetic nervous systems are listed below.

Target organ/system Parasympathetic Sympathetic
Digestive system Increase peristalsis and amount of secretion by digestive glands Decrease activity of digestive system
Liver No effect Causes glucose to be released to blood
Lungs Constricts bronchioles Dilates bronchioles
Urinary bladder/ Urethra Relaxes sphincter Constricts sphincter
Kidneys No effects Decrease urine output
Heart Decreases rate Increase rate
Blood vessels No effect on most blood vessels Constricts blood vessels in viscera; increase BP
Salivary and Lacrimal glands Stimulates; increases production of saliva and tears Inhibits; result in dry mouth and dry eyes
Eye (iris) Stimulates constrictor muscles; constrict pupils Stimulate dilator muscle; dilates pupils
Eye (ciliary muscles) Stimulates to increase bulging of lens for close vision Inhibits; decrease bulging of lens; prepares for distant vision
Adrenal Medulla No effect Stimulate medulla cells to secrete epinephrine and norepinephrine
Sweat gland of skin No effect Stimulate to produce perspiration

Sympathetic nervous system

Promotes a fight-or-flight response, corresponds with arousal and energy generation, and inhibits digestion.

Parasympathetic nervous system

The parasympathetic nervous system has been said to promote a "rest and digest" response, promotes calming of the nerves return to regular function, and enhancing digestion. Some functions of nerves within the parasympathetic nervous system include:

  • Dilating blood vessels leading to the GI tract, increasing the blood flow.
  • Constricting the bronchiolar diameter when the need for oxygen has diminished
  • Constriction of the pupil
  • Stimulating salivary gland secretion

Enteric nervous system

The enteric nervous system is the intrinsic nervous system of the gastrointestinal system. It has been described as "the Second Brain of the Human Body". Its functions include:

  • Sensing chemical and mechanical changes in the gut
  • Regulating secretions in the gut
  • Controlling peristalsis and some other movements
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