Development Of Postsynaptic Potential

DEVELOPMENT OF POSTSYNAPTIC POTENTIAL

Q. 1

Simulation of post ganglion sympathetic neurons leads to:

 A

Fast EPSP

 B

Slow EPSP

 C

Slow IPSP

 D

All

Q. 1

Simulation of post ganglion sympathetic neurons leads to:

 A

Fast EPSP

 B

Slow EPSP

 C

Slow IPSP

 D

All

Ans. D

Explanation:

A i.e. Fast EPSP, B i.e. Slow EPSP, C i.e. Slow IPSP


Q. 2

Slow IPSP in autonomic is generated by:

 A

Nicotinic cholinergic

 B

Muscarinic cholinergic

 C

Dopamine

 D

GnRH

Q. 2

Slow IPSP in autonomic is generated by:

 A

Nicotinic cholinergic

 B

Muscarinic cholinergic

 C

Dopamine

 D

GnRH

Ans. C

Explanation:

C i.e. Dopamine


Q. 3

Lowest threshold potential in a motor nerve fibre is at:

 A

Dendrite

 B

Body

 C

Axon hillock

 D

Axon

Q. 3

Lowest threshold potential in a motor nerve fibre is at:

 A

Dendrite

 B

Body

 C

Axon hillock

 D

Axon

Ans. C

Explanation:

C i.e. Axon hillock


Q. 4

Which of the following statements is true for excitatory postsynaptic potentials (EPSP):

 A

Are self propagating

 B

Show all or none response

 C

Are proportional to the amount of transmitter released by the presynaptic neuron

 D

Are inhibitory at presynaptic terminal

Q. 4

Which of the following statements is true for excitatory postsynaptic potentials (EPSP):

 A

Are self propagating

 B

Show all or none response

 C

Are proportional to the amount of transmitter released by the presynaptic neuron

 D

Are inhibitory at presynaptic terminal

Ans. C

Explanation:

C i.e. Are proportional to the amount of transmitter released by the presynaptic neuron


Q. 5

Influx of which of the following ion is responsible for IPSP (inhibitory postsynaptic potential):         

March 2005

 A

Potassium ion

 B

Chloride ion

 C

Calcium ion

 D

Sodium ion

Q. 5

Influx of which of the following ion is responsible for IPSP (inhibitory postsynaptic potential):         

March 2005

 A

Potassium ion

 B

Chloride ion

 C

Calcium ion

 D

Sodium ion

Ans. B

Explanation:

Ans. B: Chloride ion

Sodium ion

Despite their name, some neurotransmitters inhibit the transmission of nerve impulses. They do this by opening

  • Chloride channels and/or
  • Potassium channels in the plasma membrane.

In each case, opening of the channels increases the membrane potential by

  • Letting negatively-charged chloride ions (C1″) in and
  • Positively-charged potassium ions (K+) out

This hyperpolarization is called an inhibitory postsynaptic potential (IPSP).

Although the threshold voltage of the cell is unchanged, it now requires a stronger excitatory stimulus to reach threshold. Example: Gamma amino butyric acid (GABA). This neurotransmitter is found in the brain and inhibits nerve transmission by both mechanisms:

  • Binding to GABAA receptors opens chloride channels in the neuron.
  • Binding to GABAB receptors opens potassium channels.


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