The introduction reads, “Neural communication involves different processes within and between neurons. In this infographic, we follow the electrical action that conveys messages within the neuron, from one end to the other.”
The main graphic shows an illustration of a nerve cell. A ball-shaped object at the end is labeled “Neuron cell body.” Multiple filaments extending from the neuron cell body are labeled “Dendrites.” At the lower right, a tube extends from the neuron cell body; the area where the tube originates is labeled “Axon hillock” and the tube is labeled “Axon.” Segmented tubes surrounding the axon are labeled “Myelin sheath,” and the spaces between the segments are labeled “Node of Ranvier.” At the lower end of the axon are several branching tips with rounded ends, labeled “Terminal buds.”
A magnified illustration extends from the axon hillock area and shows a cross-section of a tube. A row of “+” signs are shown along the outside of the tube at the top and bottom, and rows of “-” signs are shown on the inside of the tube at the top and bottom. There are two additional + signs within the tube. A callout to the illustration reads as follows:
Before communication begins, the neuron is “at rest.” Closed channels in the cell membrane prevent some positive ions from entering the cell, and the voltage inside of the cell is slightly more negative than the voltage outside. At –70 mV, the cell is at its resting potential.
An illustration at the right shows three cross-sections of axon tube. The left is labeled “A,” and shows row of “+” signs along the outside of the tube at the top and bottom, and rows of “-” signs on the inside of the tube at the top and bottom. There are two additional + signs within the tube. The center cross-section is labeled “B,” and shows row of “-” signs along the outside of the tube at the top and bottom, and rows of “+” signs on the inside of the tube at the top and bottom. An arrow labeled “+” points from the outside to the inside of the tube at the top and bottom. The right cross-section is labeled “C,” and shows row of “+” signs along the outside of the tube at the top and bottom, and rows of “-” signs on the inside of the tube at the top and bottom. An arrow labeled “-” points toward the outside from the inside of the tube at the top and bottom. A graph is drawn above the graphic, color-coded per the cross-section graphics. The Y-axis shows values including -70, -55, 0, and +30, with a horizontal dashed line at the -55 mark. The segment corresponding to the A graphic shows a line starting at the -70 mark, and extending upward to the -55 mark. The segment corresponding to the B graphic shows the line jumping to the +30 mark on the graph. The segments corresponding to the C graphic shows the line dropping quickly to a point lower than -70 on the graph, then rising again and leveling off.
A callout to the illustration reads as follows:
This graph shows the characteristic electrical trace of the action potential. When the neuron is stimulated, positive ions enter the cell, making the axon less negative (A). When the charge reaches threshold (–55 mV), an action potential is triggered. Positive ions flood the cell, quickly reversing the charge from negative to positive (B). Afterward, the cell is restored to resting potential (C). The lower graphic shows three illustrations of Axon segments. In each, a tube represents the axon, and covering segments along the tube represent the myelin. The spaces between the myelin segments are labeled “Node of Ranvier,” and each illustration shows three node sections. In the top illustration, the outer node shows – icons in the first node and + icons in the second and third nodes. Within the tube, the first area corresponding to the node shows +, and the remaining two areas show -. A lightning bolt pointing right indicates the direction of transmission. A drawing of the action potential graph above the illustration shows the peak above the first – Node of Ranvier segment. The second and third illustrations show the progression of the voltage down the axon. In the second illustration, the center node section shows the – icons outside the tube and + inside the tube, with the lightning bolt pointing right from this segment. A drawing of the action potential graph shows the peak above the center Node of Ranvier segment. In the third illustration, the right node section shows the – icons outside the tube and + inside the tube, with the lightning bolt pointing right from this segment. A drawing of the action potential graph shows the peak above the right Node of Ranvier segment.
A callout to the graphic reads as follows:
The action potential occurring in one axon segment causes a voltage change in the next, initiating an entirely new action potential there. This sequential action travels along the axon like a wave, carrying the message from axon hillock to terminal buds.