The resting potential to the threshold potentialįrom the grated potentials, but now that all this Membrane potential, which has already gone from Permeability to sodium is dramatically increased. Gated sodium channels will open that the membrane Sodium channels which is why action potentials usually The greatest density of these voltage gated Triggering each other in a wave that rapidly To flow in further depolarizing the membrane and opening the Piece of the membrane so that more sodium is going Voltage gated sodium channels in the next This is going to cause anĮxplosive chain reaction by triggering the These positive charges now on the inside. That part of the membrane to depolarize from all So when this voltage gatedįlow into the neuron through the open channel causing Strongly trying to drive them into the neuron. Recall that the electricalĪnd diffusion forces acting on sodium ions are This voltage gated ionĬhannel has a mechanism to sense this voltage change. Soma into the initial segment of the axon, the trigger zone. Potentials spreading across the membrane of the The initial segment of the axon, so let me just To get us toward the threshold, here at the trigger zone, at ![]() Temporal and spatial summation of excitatory grad potentials If these voltage gated ion channels will open. This threshold potential is that it determines So many neurons would haveĪ resting membrane potential of around negative 60 millivoltsĪnd a threshold potential of around negative Vary between different types of neurons, but these wouldīe fairly common values. Most of which open when the membrane potentialĬrosses a threshold value. New type of channel that I've drawn in dark grey The action potential, I need to introduce an entirely Ligand gated ion channels like the neurotransmitter The first in this lighter greyĪre the leak channels that we talked about when we talkedĪbout the neuron resting potential. And now I've put a couple ofĭifferent kinds of ion channels in the membrane of the axon. ![]() And I've blown up theĪxon to a very large size just so I had some room to draw. Trigger zone and how they're conducted down the axon. I hope this helps.Ībout how action potentials are generated the When we say the channels are chemically-gated, we mean the key to opening the channels is the chemical. When we say voltage-gated, we mean the key to opening the channels is the change in voltage. When it reaches the axon terminal, then the neuron releases a neurotransmitter on another neuron so the process can continue and we can have thoughts. If enough gates on the soma open up, and cause the axon hillock to reach threshold, then the voltage gates on the axon will open, moving the action potential down the axon. This means that when their receptors bind to the neurotransmitter (the chemical) those channels open letting Na ions in, changing the inside environment to be closer to threshold or depolarizing the soma. The dendrites and cell body or soma have chemically-gated channels. They open up letting Na ions in, that changes the inside of the axon there, so the next channel opens, and so on all the way down to the end or the axon terminal. Channels on the axon are voltage-gated, they open when the voltage on the axon hillock reaches threshold ( around -55volts). Second let me apologize for the fact that English is so hard and neurology is hard so together, the work is very difficult. First, let me tell you how wonderful you are to work so hard in English, which is not your language.
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