3-19 conduction and transmission of neural signals

3-19 conduction and transmission of neural signals -...

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CONDUCTION AND TRANSMISSION OF NEURAL SIGNALS LIFE 44.2 – 44.3 44.2 How do neurons generate and conduct signals? - Action potentials are generated when ion channels in the plasma membranes of neurons open for a short time and permit ions to move across the membrane. The movement of these charged molecules is driven by differences in their concentration gradients and by electrical charge differences on the two sides of the membrane = membrane potential - When the neuron is resting and not firing action potentials , the membrane potential is called a resting potential 44.2.1 Simple electrical concepts underlie neuronal function - Voltage (electric potential difference) is a force that causes electrically charged particles to move between two points - in solutions and across cell membranes, electric current is carried by ions - ions with opposite charges attract one another, and those with like charges repel one another 44.2.2 Membrane potentials can be measured with electrodes - any chemical or physical stimulus that changes the permeability of the plasma membrane to ions will produce a change in the cell’s membrane potential - action potential : a sudden and rapid reversal in the voltage across a portion of the plasma membrane . For 1 or 2 milliseconds, positively charged ions flow into the cell, making the inside of the cell more positive than the outside 44.2.3 Ion pumps and channels create membrane potentials - Ion pumps and channels are responsible for the distribution of charges across the membrane that create resting and action potentials - A major ion pump in the plasma membranes of neurons (and all other cells) is the sodium–potassium pump , so called because it actively expels Na + from inside the cell, exchanging it for K + from outside the cell (requires ATP) -The sodium–potassium pump keeps the concentration of K + inside the cell greater than that of the extracellular fluid, and the concentration of Na + inside the cell less than that of the extracellular fluid - Ion channels permit the diffusion
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3-19 conduction and transmission of neural signals -...

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