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प्रश्न
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उत्तर
Reflex action - It is an immediate and involuntary response to a stimulus.
Example - 1. Blinking of eyelids on exposure to light .
2. Knee jerk.
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संबंधित प्रश्न
What is the role of the brain in reflex action?
With the help of a neat and labelled diagram, describe reflex arc.
The diagram given below shows the internal structure of a spinal cord depicting a phenomenon. Study the diagram and answer the questions:
1) Name the phenomenon that is depicted in the diagram. Define the phenomenon.
2) Give the technical term for the point of contact between the two nerve cells.
3) Name the parts numbered 1, 2 and 3.
4) How does the arrangement of neurons in the spinal cord differ from that of the brain?
5) Mention two ways by which the spinal cord is protected in our body.
A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.
What is a reflex action? Explain with the help of an example.
When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers and impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.
(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
(b) What is (i) neuron S, and (ii) neuron T?
(c) Name the tissue U.
(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
(e) Name the effector in this whole process.
What is the difference between reflex action and voluntary action?
Explain the following term :
Conditioned reflex
Which one of the following is not a simple reflex?
Which of the following is not an involuntary action?
