Chapter 39, Problem 1MC

Summary Introduction

Introduction:

A neuron is a specialized cell that carries electrical impulses. Neurons are called as the basic units of the nervous system that plays important role in brain. Neuron is made up of some important structure such as dendrites, axon and nerve fiber. These structures help neuron in transmitting and receiving the electrical signals.

Answer to Problem 1MC

Correct answer:

A change in the voltage across a neuron’s plasma membrane that makes the neuron less likely to fire an action potential is an inhibitory postsynaptic potential. Therefore, option (c) is correct.

Option (c) is given as “an inhibitory postsynaptic potential”.

Explanation of Solution

Justify reason for the correct statement:

Whenever the voltage across a neuron’s plasma membrane change, it will make neuron less active. So, it will not fire an action potential, no signal transmission will occur. In this the neuron will become more negative; it is called as inhibitory postsynaptic potential.

Hence, option (c) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “a change that makes the resting potential less negative”.

Resting potential occur whenever there is an imbalance of electrical charge that exists between the interior of electrically excitable neuron. Hence, it is a wrong answer.

Option (b) is given as “an excitatory postsynaptic potential”.

In an excitatory postsynaptic potential makes the postsynaptic neuron to fire an action potential. Hence, it is a wrong answer.

Option (d) is given as “a change that lowers the threshold”.

Threshold potential is a membrane potential. It occurs due to increase and decrease of sodium and potassium ions. Hence, it is a wrong answer.

Hence, options (a), (b), and (d) are incorrect.

Conclusion

Whenever the voltage across the neuron changes then the postsynaptic neuron will become less active and it will result in inhibitory postsynaptic potential.