Final answer:
The speed of nerve signal conduction is most significantly influenced by the presence of myelin and axon diameter. Myelin acts as an insulator to prevent current leakage, which greatly enhances signal speed through saltatory conduction. The size of the axon also impacts resistance and therefore affects signal speed.
Step-by-step explanation:
The factors that influence the speed of nerve signal conduction include the presence of myelin, axon diameter, ion concentrations, and structure of synapses. Myelin is an insulating layer that surrounds nerves in the brain and spinal cord and is crucial for fast signal transmission. Unmyelinated axons conduct signals more slowly than myelinated ones, and this effect is part of what underlies various neurological diseases.
In response to the given context, myelin allows for effcient nerve signal conduction due to its insulating properties, enabling action potentials to 'jump' between the gaps or nodes of Ranvier in a process known as saltatory conduction. If myelin is damaged or missing, as in demyelinating diseases like multiple sclerosis, nerve conduction is impaired, leading to various neurological symptoms. Besides myelin, the diameter of the axon also plays a role, with larger axons conducting signals faster due to lower resistance to the flow of electric current.
Temperature, to a lesser extent, can affect nerve signal speed, as biochemical processes within the neuron can be temperature dependent. However, myelin presence and axon diameter are the primary physical determinants of the conduction velocity of nerve impulses.