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प्रश्न
Give a brief account of Mechanism of synaptic transmission.
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उत्तर
Mechanisms of synaptic transmission
synapse is a junction between two neurons. It is present between the axon terminal of one neuron and the dendrite of next neuron, separated by a cleft.
There are two types of synaptic transmission.
- Chemical transmission
- Electrical transmission
1. Chemical transmission:
- When a nerve impulse reaches the end plate of the axon, it releases a neurotransmitter (acetylcholine) across the synaptic cleft. This chemical is synthesised in the cell body of the neuron and is transported to the axon terminal.
- The acetylcholine diffuses across the cleft and binds to the receptors present on the membrane of the next neuron. This causes depolarization of membrane and initiates an action potential.
2. Electrical transmission:
- In this type of transmission, an electric current is formed in the neuron. This electric current generates an action potential and leads to the transmission of nerve impulses across the nerve fibre.
- This represents a faster method of nerve conduction than the chemical method of transmission.
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संबंधित प्रश्न
Compare the following:
Resting potential and action potential
Explain the following process:
Transmission of a nerve impulse across a chemical synapse
Complete the flowchart of the process of conduction of nerve impulses.
| Application of stimulus on a resting nerve |
| ⇓ |
| Permeability of membrane changes |
| ⇓ |
| ______________________________ |
| ⇓ |
| Positive ions inside axon increases |
| ⇓ |
| ________________________________ |
| ⇓ |
| Polarity reverses and depolarisation takes place |
| ⇓ |
| Repolarisation - potassium gates open |
| ⇓ |
| ______________________________ |
| ⇓ |
| ______________________________ |
| ⇓ |
| Axoplasm becomes negatively charged and ECF becomes positive |
Dendrites transmit impulse ______ cell body and axon transmit impulse ______ cell body.
What are the number of Na+ ions pumped out, and K+ ions pumped into the cell, with respect to the Na+ - K+ pump?
Which ions is the resting membrane more permeable to?
Match the Column - I with Column - II:
| Column I | Column II | ||
| i. | P - wave | p. | Depolarisation of ventricles |
| ii. | QRS complex | q. | Repolarisation of ventricles |
| iii. | T - wave | r. | Coronary ischemia |
| s. | Development of atria | ||
| t. | Repolarisation of atria |
Neurotransmitters are removed from synaptic cleft by ____________ after transmission of impulse.
What is the average potential difference across the nerve cell membrane?
Under which of the following conditions will the ionic gradients across the resting membrane be maintained?
Identify the correct path of transmission of nerve impulse.
Which of the following statements is TRUE for medullated nerve fibre?
Resting membrane potential is maintained by ______.
During resting potential, the axonal membrane is polarised, indicate the movement of +ve and –ve ions leading to polarisation diagrammatically.
Complete the statement by choosing appropriate match among the following -
| a. Resting potential | i. Chemicals involved in the transmission of impulses at synapses. |
| b. Nerve impulse | ii. Gap between the pre synaptic and post synaptic neurons |
| c. Synaptic cleft | iii. Electrical potential difference across the resting neural membrane |
| d. Neurotransmitters | iv. An electrical wave like response of a neuron to a stimulation |
Explain the process of the transport and release of a neurotransmitter with the help of a labelled diagram showing a complete neuron, axon terminal and synapse.
The electronegativity inside the membrane is due to
