Trace the events occurring in a reflex action such as sneezing?

Sneezing is a reflex action that does not require conscious direction or control.

The entire process of response to a peripheral nervous stimulation that occurs involuntarily is called a reflex action. It is defined as an inborn, involuntary mechanical response to stimuli. The reflex pathway comprises at least one afferent neuron and one efferent neuron appropriately arranged in a series. The afferent neuron receives signal from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS. The efferent neuron then carries signals from CNS to the effector.

The sequences of events occurring during sneezing are:

• Nerve endings located in the nasal passage identifies the irritant entered in the nose.

• Receptor sends the information or nerve impulse to the sneezing centre located in the brain stem.

• Brain stem sends instructions to the lungs or diaphragm for response.

• Diaphragm moves abruptly and the chest muscles contract in response to the instructions received.

• Air blows out from nose and mouth rapidly.

• Sneezing occurs in response to the irritant.