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Question
Explain the mechanism of reflex action with the help of a suitable diagram.
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Solution
Mechanism of Reflex action : The reflex action is completed in a series of events. The events that occur are,
(1) Pricking of needle stimulates skin receptors by receiving stimulus,
(2) Sensory impulse is formed and it is carried by denderites innervating the skin.
(3) Impulse is carried to the association neuron by axon of sensory neuron,
(4) When impulse reaches the end of the axon there is a synapse.
(5) Synaptic transmission is chemical: The synaptic buttons at the end of the axon releases a neurotransmitter substance acetylcholine. It fills the synaptic gap and helps in chemical transmission of the impulse from axon of one neuron to dendron of the other neuron. Once the impulse reaches the dendrites of association neuron, axonic buttons release an enzyme acetylcholine estrase which neutralizes the acetycholine and again a synaptic gap is formed. This mechanism helps to receive new impulse or avoid the mixing of different impules.
(6) The association neuron receive sensory impulse, interprets it, analyses it and generates motor impulse.
(7) Motor impulse again travels through synapse between association neuron and motor neuron.
(8) Impulse travels through motor neuron and reaches effector organ like skeletal muscles or the gland.
(9) The effector organ gives a proper response like contraction of the muscles or secretion by the gland.
For e.g., when the hand is pricked with a needle, immediately hand is withdrawn from the source.
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