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प्रश्न
Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?
उत्तर
As the electrical impulse reaches the axon terminal in the region of axon-dendrite synapse, it stimulates the exocytosis of vesicles containing neurotransmitter (e.g. acetylcholine). Neurotransmitter attaches to the chemoreceptor sites of the membrane covering the dendrite end of synapse. It creates a new impulse that travels through cell body and axon of the second neuron. At synapse, the axon end does not contain any chemoreceptor sites so that reverse flow of electrochemical impulses is not possible.
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संबंधित प्रश्न
Differentiate between Spinal nerves and Cranial nerves (number of nerves).
The diagram given below is a representation of a certain phenomenon pertaining to the nervous system. Study the diagram and answer the following questions:
(i) Name the phenomenon which is being depicted.
(ii) Give the technical term for the point of contact between the two nerve cells.
(iii) Name the parts 1, 2, 3, and 4.
(iv) Write the functions of parts 5 and 6
(v) How does the arrangement of neurons in the spinal cord differ from that of the brain?
Differentiate between following pair with reference to the aspect in bracket.
Sensory nerve and motor nerve (direction of impulse carried)
Name the following:
The nerve which carry impulse from CNS to muscles.
Explain the following term :
Association neuron
How does an impulse travel across a synapse?
Differentiate between:
A Sensory neuron and a Motor neuron (function)
Compare and contrast.
Sympathetic Nervous System and Parasympathetic Nervous System
Nerve cells do not possess ______
Dendrons are the longest fibres that conduct impulses away from the cell body.
The longest fibre on the cell body of a neuron is called ____________.
Assertion: Impulse travels from dendrite to cell body and then along the axon to its end.
Reason: Information acquired at the end of the dendrite tip of a nerve cell sets of an electric impulse.
Electrical impulse travels in a neuron from
Identify the parts of a neuron which help the nerve impulse to travel towards the cell body.
The basic structural and functional unit of brain is ______.
Nissl's granules are found in the cytoplasm of ______.
Note the relationship between the first two words and suggest the suitable word/words for the fourth place.
Axons : Nerve :: Cytons : ______.
Distinguish between the following pair:
Nerve impulse and flow of electricity (transmission and speed)
The figure given below is the basic structural and functional unit of the human nervous system. Study the diagram and answer the following questions:
 |
- Write the technical term for the diagram.
- Name two organs of our nervous system where these cells are richly found.
- How are these cells significant for us?
- Name the cell organelle that is absent in these cells and how does it affect our body metabolism?
- Redraw the same figure and label the following Perikaryon, Axon, Dendrites, Myelin sheath and Node of Ranvier.
