Explain the mechanism of reflex action with the help of an example.
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Solution
Reflex action:
Reflex actions are involuntary and automatic reactions to a stimulus or a change in an organism's internal or external surroundings.
Reflex action can be natural such as coughing or sneezing. Some reflex actions are conditioned or acquired, such as salivation from smelling delicious food.
Components of reflex action:
The pathway of reflex action is called reflex arc, and its components are-
Receptor- It is the sensory tissue or organ which receives the stimulus needed to generate an impulse.
Sensory neuron- It is the neuron that transfers the impulse generated from the receptor to the central nervous system.
Spinal cord- It contains the relay neurons that transfer the impulse from the sensory neuron to the motor neuron.
Motor neuron- It transmits the impulse to the effector organ or muscle.
Effector organ- It is the last component of the reflex arc and generates a suitable response to the stimulus received from the receptor.
Mechanism:
The mechanism of reflex action can be studied with the help of an example showing the withdrawal of a hand from a hot object. This is called a spinal reflex arc. The steps are-
The specific receptors present in the skin receive the sensation of heat or pain.
This sensation of heat or pain is first transferred to the dorsal root of the spinal nerve via sensory neurons and then to the spinal cord.
The nerve impulse is further carried to the relay neuron in the spinal cord, also termed an interneuron, from where it reaches the motor neuron.
The motor neuron emerges from the ventral root of the spinal cord and reaches the effector muscles, which initially felt the temperature rise.
The muscles in that area respond to the stimulus, and the hand turns away from the hot utensil
