What is reflex action? Explain the reflex arc in human beings.

Reflex action is a sudden and involuntary response to stimuli. It helps organisms to quickly adapt to an adverse circumstance that could have the potential to cause bodily harm or even death. Pulling our hands away immediately after touching a hot or cold object is a classic example of a reflex action. The neural pathway that controls the reflexes occurs through the reflex arc. It acts on an impulse even before it reaches the brain. There are some stimuli that require an automatic, instantaneous response without the need for conscious thought. The following diagram shows the reflex arc pathway. The receptor here is the sense organ that senses danger. The sensory neurons pick up signals from the sensory organ and send them through other neurons which are interconnected. It is then received by the relay neuron which is present in the spinal cord. Immediately, the spinal cord sends back signals to the muscle through the motor neuron. The muscles attached to the sense organ move the organ away from danger. In reflex actions, the signals do not travel up to the brain.