In: Anatomy and Physiology
How does the length of the wire affect the conduction of electricity? How is this problem dealt with in biological systems such as long nerves (eg nerves that have to reach to your toes)?
Length(L) of wire is proportional to the Resistance(R) and Current (I) is inversely proportional to Resistance. This means that when length of wire increases the resistance increases. When resistance increases then the flow of current decreases and vice-versa. In biological systems the impulses which are the electrical signals are conducted with help of neurons. The neurons are the structural and functional unit of nervous system. Parts of neurons are dendrites, cell body and axon. In nerves the neurons are joined together like a electric wire. Axon of one neuron joins dendrites of other neuron through synaptic junctions. At synaptic junctions neurotransmitters are released which transfers signals from one neuron to another. Dendrites receives the impulse and transfers to axons via cell body. The impulse travels the entire length of axons. But some axons are myelinated with myelin sheath which are formed from Schwann cells. There are gap between Schwann cells in myelinated axons which are called as nodes of ranvier. In such axons the impulse jumps from nodes to nodes rather travelling the entire length of axon and due to this signals can travel hundred times faster. This is how a signal can reach to toe in very less time eventhough the length of nerve is more.