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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?
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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
Draw a labelled diagram of the following:
Neuron
Distinguish between Cranial nerves and spinal nerves.
Mention the exact location of the Myelin sheath
Choose the ODD one out from the following terms given and name the CATEGORY to which the others belong:
Dendrites, Medullary sheath, Axon, Spinal cord
Describe the two parts of the nervous system.
Differentiate between following pair with reference to the aspect in bracket.
Sensory nerve and motor nerve (direction of impulse carried)
Write the function of Association neuron.
Rearrange the following in correct sequence pertaining to what is given within brackets at the end.
Repolarisation - Depolarisation - Resting (polarised) (during conduction of nerve impulse through a nerve fibre)
What are the advantages of having a nervous system?
Differentiate between:
Rods and Cones.
Brain is a part of _________ nervous system.
___________ nervous system prepares us for the fight or flight responses.
During synaptic transmission of nerve impulse, neurotransmitter (P) is released from synaptic vesicles by the action of ions (Q). Choose the correct P and Q.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of ______.
As compare to medullated nerves, the conduction of impulse by non-medullated nerve fibres is ______ times faster.
A microscopic gap between a pair of adjacent neurons over which nerve impulses pass is called ____________.
Chemicals which are released at the synaptic junction are called ______.
The basic structural and functional unit of brain is ______.
Rearrange the following in correct sequence pertaining to what is given within brackets at the end.
Axon endings - Dendrites - Axon - Perikaryon - Dendron (Neuron structur)
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.
