What is reflex action? Explain the pathway for reflex action.

Hint: An action generated by the body without thinking against any external stimulus which is harmful.

Complete answer:
A reflection action is an automated, fast, predictable motor response to a sensory stimulus without the involvement of the brain. Reflex action was first studied by Marshall hall. It is an involuntary action as there is no conscious control of the brain on it.
The Components of reflex action are:
1) Receptor organ: These are located in important organs, mostly sensory types of organs like eyes, ear, nose, tongues, and integumentary organs. They receive an external stimulus from the external environment.
2) Sensory neurons: They are afferent neurons that carry stimulus from receptors to the spinal cord.
Integrating or Association Center: It contains intermediate neurons also known as interstitial neurons which help in transferring impulses from sensory to motor neurons.
3) Motor neuron: Present is the ventral horn of the spinal cord and carry the impulses to effector organs.
Effector organs: They respond to the stimulus received from motor neurons.

Mechanism or Pathway of Reflex Action:
A reflex action starts when a stimulus is received by the sensory organs like skin, eyes, etc from the surrounding environment.
This stimulus is converted to the electrical impulse which is perceived by the sensory neurons.
These neurons carry the information to the spinal cord through axons.
In the spinal cord, this impulse then passes to the intermediate neurons.
The stimulus for a motor response then passes through the motor neurons and reaches the effector organs which perform the necessary actions needed.

Note: It is to be remembered that the whole reflex action is completed so rapidly that we immediately know when it is completed. The reflex pathway also known as reflex arc has no involvement of the brain.