Question 1
What function is served by the increased axon diameter at the nodes of Ranvier?Question 2
Imagine a neuron that has several hundred axonal knobs impinging on it. The majority of these axonal knobs are shown to be "firing." However, the neuron in question does not transmit an impulse. Give a valid explanation of why this could occur.Answer 1
Increased diameter results in less resistance to lengthwise intra-axonal flow. This results in increased speed of impulse propagation.Answer 2
Both excitatory and inhibitory potentials impinge on neurons. In this case, inhibitory postsynaptic potentials (IPSPs) outnumber EPSPs, and due to the IPSP neurotransmitter released and its action, the postsynaptic neuron is inhibited from "firing" (hyperpolarized).