Define reflex arc. Draw a  flow chart showing the sequence of events which occur during sneezing.

Reflex actions are sudden responses that do not involve thinking. It is an involuntary action that takes place in response to the stimulus made by reflex arcs.
For example, when we touch a hot object, we withdraw our hands immediately without thinking. 
Reflex arcs are formed in the spinal cord, although the information inputs also reach the brain. They have the capability to act upon impulses without reaching the brain.
A flow chart showing the sequence of events that occur during sneezing are given below:
The sequence of events which occur during sneezing are:
Nerve endings located at the nasal passage identifies the irritant entered in the nose.
                                         $\downarrow $
Receptors send this information to the sneezing centres located in the brain stem.
                                          $\downarrow $
Brain stem in turn sends the instructions to the lungs or diaphragm to respond.
                                         $\downarrow $
The diaphragm moves abnormally, chest muscles also contract in response to the instructions.
                                         $\downarrow $
Air blows out from nose and mouth instantly and rapidly and hence sneezing occurs in response to the irritant.


Simply Easy Learning

Updated on: 27-Mar-2023


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