All posts by Jaeda

Neuron Communication Summary

Neuron Structures:

Neuron Function:

There are many stages to Action Potential. The first stage is Resting Potential, where the large negatively charged ions are found inside the axon. This results in the inside of the axon having a negative charge. At this time, the Sodium ions are found outside of the axon, and the charge is -70mV. The second stage of Action Potential is Depolarization, where approaching messages stimulate a portion of the axon. Certain channels open, allowing for the Sodium ions to enter through their gates and into the axon. At this point, the voltage is increased to +30mV. The third stage to Action Potential is Repolarization, where Potassium ions come into play. New channels are opened to allow potassium to exit the axon through their gates, causing the voltage to return to its original -70mV. Repolarization, however, causes Depolarization in the next portion of the axon. This ignites the Refractory Period. When Sodium ions are found inside the axon, and Potassium ions are found outside the axon, pumps push the Sodium ions back to the outside of the axon, and push the Potassium ions back into the axon, almost representing a reset.

So, how do messages travel between neurons? This process happens through synapse.

In this process, the axon of the sending neuron possesses synaptic vesicles throughout the axon terminal and axon terminal bulb. These vesicles hold neurotransmitters within. Once the vesicles reach the presynaptic membrane, the vesicle releases the neurotransmitters into the synaptic gap, where diffusion allows the neurotransmitters to move through the gap, The synaptic gap is a small space between the axon terminal bulb of the sending neuron and the dendrites of the receiving neuron. Once the neurotransmitters reach the postsynaptic membrane, they flow to their respective neurotransmitter receptors.

Their message can be received as excitatory or inhibitory depending on the neurotransmitter. However, there are several neurotransmitters that can be viewed as excitatory and inhibitory. For those that are both, whether it is received as excitatory or inhibitory relies entirely on the receptor it is attached to. Excitatory received messages stimulate the Action Potential of the receiving neuron, whereas Inhibitory received messages repress the Action Potential of the receiving neuron. Any leftover neurotransmitters are bound to a synaptic gap neurotransmitter recycler, where it breaks the neurotransmitter down, and sends its parts back to the axon terminal bulb.

It’s important to note that neurotransmitters are the key to the receptor lock. In theory, only the right neurotransmitter could fit with the proper receptor. However, there are agonists and antagonists that could result in the neurotransmitters not reaching their proper receptors. Agonists are those that mimic the shape of a neurotransmitter and bind to the receptors, such as nicotine which has a similar shape to acetylcholine. Antagonists are those that block the receptor and the neurotransmitters from binding together. Snake venom is an example, as it blocks the acetylcholine receptor, and may cause muscle paralysis.