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| Reflex Action - Simple Or Unconditioned Or Natural Reflex |
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| When the stimulation of a receptor results in a spontaneous, involuntary reaction, it is called reflex action or simply reflex. These are described as involuntary actions as no conscious awareness, throught or decision is required for their operation. |
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| Reflexes are of two types |
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| In this type of reflex, the brain is not involved. The receptor is stimulated which is conducted to the spinal cord by the affector. The effector neuron from the spinal cord conducts a response to the muscle or the gland. This causes an immediate reaction. It does not involve any thinking or reasoning. It is a natural response and will occur even in new-born babies. For e.g., blinking of eyes when strong light falls on the eyes. |
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| Simple reflex is also of two types. |
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| In the first type, only the sensory and motor neurons of the spinal nerves are involved. |
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| Jerking of knee when tapped below the kneecap is an example. |
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| In the second type, the interneuron present in the spinal cord is also involved. |
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| The moving away of hand in response to pin-prick or heat is an example of this type. |
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| In the above diagrams, it can be seen that the pathway of conduction is in the form of an arc. Thus, these pathways are also called the reflex arcs. Impulses can flow only in a single direction in a reflex arc. |
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