Question

What is Reflex Arc? Draw a flowchart showing of the events which occur during sneezing.

Answer 1

Hint: The Reflex Arc is related to the reflex actions on the basis of how the stimulus is identified and the instructions to respond to that stimulus are sent to the concerned cells from the brain or spinal cord.

Complete answer
A reflex arc can be defined as the complete pathway taken by the nerve impulses in order to facilitate a response during a reflex action. These responses are governed by the spinal cord but the impulses also reach the brain. The Reflex arcs are involuntary in nature based on the training and habits of an individual.
The sneezing is an involuntary response to a foreign substance in the nasal tract which might be the cause of the blocking of the tract. The following are the events that take place during sneezing:
1. The foreign substance is identified as a threat by the sensory neurons in the nasal tract and an impulse is sent to the spinal cord.
2. The impulse carried to the spinal cord by the receptor neurons is identified and the motor neurons carry responsive impulses to the effector muscles via motor neurons.
3. The impulses are received by the lungs and the diaphragm which respond accordingly.
4. The diaphragm contracts and expands in an abnormal manner, causing the lungs to blow out air instantaneously.
5. The tracheal muscles contract and the foreign substance is thrown out of the nasal tract, completing the sneeze.

Note:
The reflex arcs do not involve the brain and are mostly controlled by the spinal cord itself. These are generated when there is an emergency situation where a quick response is required to be given by the cells, such as sneezing or removing hands on touching a hot object.