What correctly describes the path of the electrochemical signal though a single neuron as it is received then processed then relayed down the legnth of a neuron?

Answer 1

A neural signal is received at a neuron when neurotransmitters released by a pre-synaptic neuron diffuse across the synaptic cleft and settle in to receptor sites on ligand-gated sodium ion pores typically located on the dendrites or dendritic spines of the post-synaptic neuron.

As the ligand-gated pores open, sodium ions enter the neuron, and their electric fields repel one another down the dendrite and across the soma (body of the neuron), by a process known as electrotonic conduction. This is considered a graded response, because it can vary from small to large values.

If enough sodium ions pile up at the end of the soma where the axon begins (the axon hillock), by a summation of either multiple or fast inputs, yielding a voltage above the trigger voltage, it will trigger the opening of voltage-gated sodium ion pores in the initial segmentof the axon.

As sodium ions pour into the axon through the v-gated ion pores, they open nearby v-gated sodium ion pores, more sodium ions come in, more v-gated ion pores open, and this process continues down the length of the axon in a process known as the action potential.

When the action potential reaches the ends of the axon, the axon terminals, the voltage causes voltage-gated calcium ion pores to open, allowing calcium ions into the axon terminals, which instigate a biochemical process to occur which causes small sacs (called vesicles) containing messenger chemicals called neurotransmitters to be moved into contact with the cell membrane, where they fuse with the membraneand release their contents into the synaptic cleft.