091208 - NEURAL COMMUNICATION: cellular level Every cell is...

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NEURAL COMMUNICATION: cellular level Every cell is attached to other cells and around the cells (ECM); if you measure the electrical charge b/w the inside and outside of the cell different; the black electrode here is in ECF, and the red electrode is going to get into the cell; ECF is always positively charged compared to the ICF The graph measures the difference b/w the black and red electrode, and so when the black electrode is in the ECF and the red electrode not yet in the neuron, but in the ECF, there’s not difference b/w them, but once the electrode goes into the cell, you can see the difference is about -60mV Communication in neurons depends on both electrical and chemical events, and today we’re going to focus on the electrical events Demonstration of how the inside of the neuron is negatively charged and the outside it positively charged MOVEMENT OF IONS Generally properties of ions; if you dump a substance into liquid, it will diffuse to make the distribution equal across the liquid Diffusion through semipermeable membranes: can only allow a certain type of ion through, so in this case, the blue ions are allowed to go through this mb but the red ones are not, and b/c the blue want to diffuse, will go to other side Property of electrostatic attraction and withdrawal your cells and your ECF are filled w/ anions and cations; the lower part of this diagram is specially an axon of a neuron, and outside of the cell is positively charged, and what makes it positively charged is that there are a lot of Na+ ions Outside the cell, there are not as many K+ ions even though they are positively charged, found mostly on the inside; Cl- ions on the outside of the cell, but there are more Na+ ions than there are Cl-, making it positively charged Also a lot of Ca+ and it’s not necessarily involved in the action potential or the electrical components, but will be involved later down the line in the chemical component Inside of the cell: proteins that are negatively charged, and they generally don’t leave the cell, so they are what keeps the cell negatively charged b/c there are so many of them in there, and it’s very rare that they would leave Also as I said before, there are a lot of K+ ions inside the cell, and that is the positively charged component of what is inside the cell, and that’s the majority of the ICF Both kinds of anions and cations on both sides, and they go back and forth except the proteins, but under normal resting conditions, the outside is positive and the inside is negative At resting potential which basically means that nothing is going on, the inside of the cell is roughly around -60mV, and that can range b/w -50 and -80 but the ideal state is -60, and the mb is semipermeable to K+ which come and go whereas the proteins stay inside the cell When the cell reaches its EQ, it means that the number of K+ coming in is equal to the number of K+ going out While the cell is at its resting potential, there is this Na+-K+ pump that helps to maintain the -60mV balance by sending Na+ ions out and bringing K+ in,
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This note was uploaded on 02/14/2009 for the course PSY 308 taught by Professor Jones during the Fall '08 term at University of Texas at Austin.

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091208 - NEURAL COMMUNICATION: cellular level Every cell is...

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