NEUROPHYSIOLOGY SEPTEMBER 25 slides 1 lecture done by Phenis refer back to PowerPoint when studying Electrical communication occurs within neuron Chemical communication occurs between neurons Neuron has more negative charge inside neuron than outside of neuron also known as the resting membrane Membrane itself will not let large or charged ions through which is why it is semi permeable Active transport requires energy Passive transport through ion channels does not require energy Electrostatic pressure same charges repel opposite charges attract Chemical force equals the electrical force chemical equilibrium Pumps vs channels channels allow free ion diffusion channels allow ions to move against the concentration gradient For every 3 sodium 2 potassium go in in sodium potassium pump Membranes contain a great deal of potassium receptors Where are potassium and sodium at rest K is at rest inside the cell Na at rest outside the cell Based on concentration gradient where do k and Na want to go K wants to go out Na wants to go in Moving ions against their concentration gradient requires active transport with energy ATP Why do ions need to be pumped this way To maintain negative resting potential endrites receive signals that change neurons permeability to ions dendrites receive neurotransmitters Graded potentials hyperpolarizing is inhibitory depolarizing is excitatory IPSP inhibitory post synaptic permeability EPSP excitatory post synaptic permeability What channels could cause an EPSP Sodium and calcium channels What channels would cause an IPSP Chloride or potassium channels Properties of synaptic potentials Graded more ion channels open on post synaptic membrane you ll have larger magnitude of membrane Small each individual synapse is a small change in membrane potential Spread spreads to different parts of the membrane degrades over time and space Degrade dependent on resistance diameter of cable another way of looking at axon dendrite Graded potential summation EPSP AND IPSP will cancel each other out Both have to migrate down to axon hillock to be summated IPSP generally keeps the membrane under threshold because they are inhibitory Temporal summation potentials one after another more constant and steady summation Neurotrans binds to membrane receptor opens Cl channel What happens to Na and k Name two ways in which Epsp and ipsp summated temporal and Cl goes into the cell making IPSP Na flows into cell EPSP K flows out of cell makes IPSP Communication 1 Resting membrane potential 2 Graded synaptic potentials 3 Action potential 4 Neurotransmitter release Resting membrane potential applies to entire neuron same t out EPSP AND IPSP when summated together at same time they bring cell back to resting potential of 70mv
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