Nervous transmission：練習問題

Which factor explains why nerve impulses travel faster along myelinated axons than along non-myelinated axons?

Which of the following best describes the mechanisms that maintain the resting potential of a mammalian neurone at approximately \(-70\) mV?

What is the direct effect of an inhibitory postsynaptic potential (IPSP) on the membrane of a postsynaptic neurone?

During an action potential, the membrane potential reaches a peak of approximately \(+40\) mV. Which event is directly responsible for the subsequent repolarization phase of the membrane?

Explain why the speed of transmission of a nerve impulse along a myelinated axon is significantly greater than along a non-myelinated axon of the same diameter.

Discuss how the properties of the axon membrane and the specific action of the sodium-potassium pump maintain a resting potential of approximately \(-70\) mV.

Explain the formation of an inhibitory postsynaptic potential (IPSP) and how it reduces the probability of an action potential being generated in the postsynaptic neuron.

Synaptic transmission is the process by which a signal is passed between neurons.
(a) Describe the sequence of events that occurs at a cholinergic synapse following the arrival of an action potential at the presynaptic knob.
(b) Distinguish between excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) in terms of their effect on the postsynaptic membrane potential.

The transmission of a nerve impulse relies on the movement of ions across the axon membrane. The provided data shows an oscilloscope trace of an action potential where the potential difference changes from a resting state of \( -70 \) mV to a peak of \( +40 \) mV before returning to a hyperpolarized state of \( -85 \) mV.
(a) Explain the electrochemical changes and ion movements responsible for the depolarization and repolarization phases shown on the trace.
(b) Discuss why the speed of conduction is significantly higher in myelinated axons compared to non-myelinated axons, referencing the role of saltatory conduction.