Question

The conduction of a signal in an axon through cable properties alone is _____________ due to the high internal resistance and the loss of ions through the membrane.

Answer 1

Signal conduction in an axon is inefficient when only cable properties are involved, due to high internal resistance and ion loss. Continuous conduction in unmyelinated axons is slow, while saltatory conduction in myelinated axons is faster. Axon diameter and myelination both influence the speed of nerve signal transmission.

Step-by-step explanation:

The conduction of a signal in an axon through cable properties alone is inefficient due to the high internal resistance and the loss of ions through the membrane. This process is known as continuous conduction and is observed in unmyelinated axons where voltage-gated Na+ channels are located along the entire length of the cell membrane, causing a slow propagation of the action potential. In contrast, saltatory conduction occurs in myelinated axons and is much faster, as the action potential effectively 'jumps' from one node of Ranvier to the next, thanks to the presence of voltage-gated Na+ channels only at these nodes.

Factors such as myelination and the diameter of the axon play crucial roles in signal transmission speed because they influence resistance and the spread of depolarization. While myelination reduces capacitance and allows for faster signal transmission by insulating the axon, a wider axon diameter decreases internal resistance, allowing for faster ion diffusion, analogous to water flowing more easily through a wide river than a narrow creek.

Answer 2

The conduction of a signal in an axon through cable properties alone is inefficient due to the high internal resistance and the loss of ions through the membrane.

Step-by-step explanation:

Signal conduction in an axon is inefficient due to internal resistance and ion loss, with myelinated axons conducting signals faster than unmyelinated ones due to saltatory conduction.

In unmyelinated axons, continuous conduction is slow because voltage-gated Na+ channels open continuously along the membrane.

On the other hand, myelinated axons exhibit saltatory conduction, which is much faster, as the action potential leaps from one node of Ranvier to the next.

The diameter of the axon also affects conduction speed, as larger diameters reduce resistance and allow for faster transmission of the action potential.