Communication within Neurons

An introductory text 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 infographic shows structure of neuron with its parts labeled as follows: Dendrites, Neuron cell body, Axon, Axon hillock, Myelin sheath, Node of Ranvier, and Axon terminals.

1. The neuron at rest: a schematic shows a magnified cross-sectional view of an axon. The inner surface of the axon is negatively charged whereas the outer surface is positively charged. The positive ions flow into the axon. Accompanying text reads, 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 negative 70 millivolts, the cell is at its resting potential.
2. The action potential: a schematic shows three cross sectional views of an axon with a graph. Cross section A shows the neuron at rest where the inner surface of the axon is negatively charged and the outer surface is positively charged. Cross section B shows the inner surface of the axon negatively charged and the outer surface positively charged; the positive ions pass through the channel. Cross section C – the inner surface of the neuron is negatively charged and the outer surface is positively charged; positive ions move out of the channel. The readings on the vertical axis of the graph range from negative 70 to positive 50 in varying increments. A dashed line originates from negative 55 on the vertical axis and traverses parallel to the horizontal axis. The curve in the graph originates from negative 70 on the vertical axis, ascends gradually initially (corresponds to cross section A), after which it rises steeply to a peak value (Corresponds to cross section B) that corresponds to 30 on the vertical axis; the curve descends steeply thereafter to a minimum (corresponds to cross section C). Accompanying text reads, 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 the threshold (negative 55 millivolts), 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).
3. Action potential travels length of axon: A schematic shows three cross sectional views of an axon, each with three nodes of Ranvier. The Myelin sheath is labeled. The action potential flows through the axon from the cell body of the neuron.

Cross section 1: the first node has a negatively charged ions, the second and the third nodes have positively charged ions. A high pitched pulse corresponds to the first node, it traverses toward the second node on the right. A curve is shown above, with its peak value corresponding to the first node.

Cross section 2: the first and the third nodes have positively charged ions; the second node has negatively charged ions. A high pitched pulse corresponds to the second node, it traverses toward the third node on the right. A curve is shown above, with its peak value corresponding to the second node.

Cross section 3: the first and the second nodes have positively charged ions; the third node has negatively charged ions. A high pitched pulse corresponds to the third node, it traverses toward the right. A curve is shown above, with its peak value corresponding to the third node.

Accompanying text reads, 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 axon terminals.