Sympathetic VS Parasympathetic Nervous System

The sympathetic vs parasympathetic system is a part of the autonomic nervous system. The autonomic nervous system is a well regulated and self-controlled system and controls the very important parts of our body. These include,

• Heart rate
• Respiration
• Smooth muscles contraction and relaxation
• Gastrointestinal system
• Urinary and reproductive system
• Glands of the body

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Parasympathetic Nervous System

Parasympathetic nervous system or PNS is also known as “rest and digest system” and it is usually activated when the body is in a resting condition.

Functions of PNS

• This system causes increased blood flow to the digestive organs such as stomach, intestines and to the excretory system such as urinary bladder and increases promotes their job.
• PNS also induces sleep by various mechanisms.
• It controls the heart rate and causes a depression in the heart rate and respiratory rate.
• It also controls the sexual responses of the body.

Neurotransmitter of parasympathetic system

Acetylcholine is the main neurotransmitter of this system. Acetylcholine controls the vital functions of PNS, such as contraction and relaxation of the smooth muscles.

Cranial nerves III, VII, IX & Vagus nerve are the major pathways used in this system.

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Sympathetic Nervous System

It is as “fight and flight system” of the body. This system gets activated, usually when the body is an emergency situation, i.e danger or emergency.

Functions of SNS

• When the body is in an emergency situation, we need more and more blood to the functioning organ, to maintain the oxygen supply. I.e increased blood supply to the limbs to run. Therefore we need to limit the blood supply to the organs like stomach etc. Thus SNS acts upon that very situation and reduces the blood supply to the organs like stomach, urinary and reproductive system, to spare maximum blood for the functioning organ.
• This system acts to increase the rate of blood pumped by the heart and the rate of oxygen exchange of the body (respiration).
• Increased blood pressure and pupillary dilation is another function of this system.

Neurotransmitters of Sympathetic Nervous System

The main neurotransmitter used in this system is Epinephrine, Nor-epinephrine, and Adrenalin.

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