1/26/2024 0 Comments Neuron all or none principle![]() Neurotransmitters are stored in vesicles in the axon terminal. There is both an electrical synapse, which relays quick□ messages to another cell, and a chemical synapse, which sends messages slowly□ to another cell. The synapse is where two neurons meet and neurotransmitters are released into it. The terminal branches of a neuron contain neurotransmitters which are then released. These neurotransmitters cross the synaptic gaps between neurons and are gathered in by dendrites of a new neuron, continuing the communication process□ Remember those neurotransmittors? Well once the message has passed through the axon, it reaches the terminal branches. Inhibitory - Pushes a neuron's "brake"□ makes it less likely for a neuron to reach action potential There are two types of signals / neurotransmitters:Įxcitatory - Pushes neuron's "accelerator"□ makes a neuron more likely to reach action potential and fire Depolarization is the process that carries the neural impulse through the axon, action potential is what must happen for the process to occur. Though you are not required to memorize the complicated steps of action potential (that's more AP Biology material!), try to know what each step of the graph means, because it can come up as a MCQ! Just understand what each section of the graph means (its signficance) and you'll be good to go!īasically, the action potential is associated with depolarization. When the charge changes, a series of signaling occurs within the neuron like a bullet □□(the speed of this electric message firing is actually 120 m/s, which is about 270 mph!! □). When enough of this signal is received, meeting the threshold, the membrane of the neuron becomes permeable, allowing the positive ions to rush into the neuron, bringing the charge of the cell to about +40mv ➕. Then, specific neuron receives neurotransmitters (more of this explained later: think of it as a signal). The negative ions are inside the neuron, while positive ions are outside the neuron. At resting state, the neuron has a negative (-70mv) ➖charge. ![]() This action potential occurs through the relocation of ions. Neurons have an all-or-none response - they either fire or they don’t. If the threshold is not met, nothing happens. If this threshold is met, the action potential occurs and the message travels down the axon via a process of depolarization. Image Courtesy of Open Source Textbook Action PotentialĪction potential must occur for the message to continue to travel down the axon. This only occurs if the neuron’s threshold has been met - meaning it has received enough stimulation□ from the original sending neuron.
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