UH BIOL 1361 - Neurons and Action Potential (6 pages)

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Neurons and Action Potential

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Neurons and Action Potential


The 23rd lecture that goes over neurons and action potential.

Lecture number:
Lecture Note
University of Houston
Biol 1361 - Intro to Biological Science
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BIOL 1361 1nd Edition Lecture 23 Outline of Last Lecture I Purpose of Circulatory System Minimize Diffusion Distance II Circulatory System III Open vs Closed IV Vertebrate Circulatory System V Cells VI Vessels VII Flow Rate VIII Fick s Law IX Flow Circuits X Pump Outline of Current Lecture I Neuron Structure II Fig 37 2 III Real Neurons IV Resting Potential V Figure 37 6 VI Description of Ion Movement VII Electrochemical Equilibrium These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute VIII IX Action Potential Graph Current Lecture I Neuron Structure be able to draw this Fig 37 5 a Dendrites i Receive signals from other neurons b Cell body i Contains nucleus and organelles c Axon i Transmits signals to other neurons or muscles II Fig 37 2 a Synapse junction of a nerve cell with another cell b Relative Terms depending on cell location in network i Presynaptic Neuron cell sending signal across synapse ii Postsynaptic Neuron cell receiving signal III Real Neurons Figure 37 3 a Cyan neuron cell bodies b Green dendrites c Red support cells glia IV Resting Potential a Resting Potential charge difference across a cell membrane of ALL body cells b Develops because of Na K movement c Ion movement through 3 membrane proteins i Na K pump requires ATP ii Passive K channels channels are always open facilitated diffusion V Figure 37 6 a There are more potassium channels versus sodium channels b The membrane is more permeable to potassium VI Description of Ion Movement a Na K Pump Pumps 3 Na out and 2 K in to the cell b Result i Na 15 mM inside ii Na 150 mM outside iii K 140 mM inside iv K 5 mM outside c Passive K Channel is always open i K leaves the cell ii Cl and Protein are stuck inside the cell iii Result charge now greater inside the cell iv charge attracts charge on outside electrical gradient limits K efflux outflow VII Electrochemical Equilibrium a X X out RT Eion zF i Eion equilibrium potential for a specific ion ii R universal gas constant 8 314 J K 1 mol 1 iii T Temperature K degrees C 273 iv Z valence of ion v Faraday s constant 96 485 Coulombs mol 1 vi X ion VIII Action Potential a Depends on voltage gated Na and K channels i Passive channels that are closed at rest ii Open in response to a change in voltage across cell membrane iii Like an electrically operated gate b Description of ion movement i Stimulus changes membrane potential voltage c If change is large enough that voltage exceeds a threshold voltage gated Na channels open d Na flows into the cell e Changes in potential CLOSES voltage gated Na channels and OPENS voltagegated K channels f K leaves the cell g Na K Pump re establishes gradients of Na and K h Action potential spreads because Na diffuses along the inside of the cell membrane changing the voltage and opening the next batch of voltage gated Na channels Graph from MasteringBio will be on final IX Graph a Resting Potential 1 i The voltage gated channels are closed b 2 i A few are open ii A few are closed c 3 i Na channels open d 4 i Voltage gated Na channels closed ii Voltage gated K channels open iii Passive Na channels open iv Passive K channels open e 5 i K channels close f Which ion channels are open during each phase of the action potential g What is represented by the dotted line i Threshold voltage AKA Threshold Potential

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