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Explain the Following Processes: Transmission of a Nerve Impulse Across a Chemical Synapse - CBSE (Science) Class 11 - Biology

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Question

Explain the following processes:

Transmission of a nerve impulse across a chemical synapse

Solution 1

Transmission of a nerve impulse across a chemical synapse: At a chemical synapse, the membranes of the pre- and post- synaptic neurons are separated by a fluid- filled space called synaptic cleft. Chemicals called neurotransmitters are involved in the transmission of impulses at these synapses. The axon terminals contain vesicles filled with these neurotransmitters. When an impulse (action potential) arrives at the axon terminal, it stimulates the movement of the synaptic vesicles towards the membrane where they fuse with the plasma membrane and burst to release their neurotransmitters in the synaptic cleft. The released neurotransmitters bind to their specific receptors, present on the post- synaptic membrane. This binding opens ion channels allowing the entry of ions which can generate a new potential in the post-synaptic neuron. The new potential developed may be either excitatory or inhibitory

Solution 2

Transmission of a nerve impulse across a chemical synapse

Synapse is a small gap that occurs between the last portion of the axon of one neuron and the dendrite of next neuron. When an impulse reaches at the end plate of axon, vesicles consisting of chemical substance or neurotransmitter, such as acetylcholine, fuse with the plasma membrane. This chemical moves across the cleft and attaches to chemo-receptors present on the membrane of the dendrite of next neuron. This binding of chemical with chemo-receptors leads to the depolarization of membrane and generates a nerve impulse across nerve fibre.

The chemical, acetylcholine, is inactivated by enzyme acetylcholinestrase. The enzyme is present in the post synaptic membrane of the dendrite.

It hydrolyses acetylcholine and this allows the membrane to repolarise

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 NCERT Solution for Biology Textbook for Class 11 (2018 to Current)
Chapter 21: Neural Control and Coordination
Q: 3.3 | Page no. 328

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Solution Explain the Following Processes: Transmission of a Nerve Impulse Across a Chemical Synapse Concept: Transmission of Impulses.
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