Question

What effect do the sympathetic nervous system and parasympathetic system have on the body ?

Answer 1

Involuntary or autonomic nervous system:

1. The involuntary or autonomic nervous system comprises pairs of chains of nerves on both sides of the vertebral column.
2. This part of the nervous system is responsible for controlling the involuntary actions of the internal organs such as the movements of the stomach and intestines, secretion from salivary glands, etc.
3. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System:

1. The sympathetic nervous system originates from the thoracic and lumbar regions of the spinal cord.
2. It prepares the body for sudden emergency conditions.
3. Noradrenaline is secreted by sympathetic fibres to activate the flight or fight response in a sudden threatening situation.
4. The action of the sympathetic nervous system causes an increase in the heartbeat, breathing rate, rate of supply of blood to the heart, constriction of blood vessels, and induces dilation of the pupil.

Parasympathetic Nervous System

1. The parasympathetic nervous system is situated anteriorly in the head and neck and posteriorly in the pelvic region.
2. The parasympathetic nervous system tries to re-establish normal body conditions after an emergency.
3. Dilatation of the peripheral blood vessels, reduced heartbeat and blood pressure, and constriction of the pupil are some of the effects of the parasympathetic nervous system.

Hence, the sympathetic and parasympathetic nervous systems act antagonistically to one another and establish a balance between the functioning of the internal organs.