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प्रश्न
Explain the mechanism of reflex action with the help of a suitable diagram.
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उत्तर
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For e.g., when the hand is pricked with a needle, immediately hand is withdrawn from the source.
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संबंधित प्रश्न
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All the voluntary actions of our body are controlled by :
(a) cerebrum
(b) cerebellum
(c) pons
(d) medulla
P is a cell (or group of cells) in the human body which is sensitive to a particular type of stimulus and conveys the messages to CNS through nerves Q. On the other hand, R is a part of the human body which can respond to a stimulus according to the instructions sent from the CNS through nerves S.
(a) What is P? Name five organs which contain cells (or group of cells) like P.
(b) Name the nerves Q.
(c) What is R? Give two examples of R.
(d) Name nerves S.
(e) How do messages travel through the nerves Q and S?
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Stimulus and impulse
With the help of suitable example, describe reflex action.
what do we refer to in the nervous system when we say:
Natural and conditioned …………………
In reflex action, the reflex arc is formed by ______
Give an example for conditioned reflexes.
State whether the following is simple reflex, conditioned reflex or neither of the two.
Sneezing
