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Animal Cell

Animal Cell. Chromatin. Axonal Membrane of a Neuron. Ion Channels. Cell membrane proteins that pass ions in and out of the cell Voltage-Gated Ion Channels gates are regulated by membrane voltage Chemical-Gated Ion Channels (also called Receptors )

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Animal Cell

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  1. Animal Cell Chromatin

  2. Axonal Membrane of a Neuron

  3. Ion Channels • Cell membrane proteins that pass ions in and out of the cell • Voltage-Gated Ion Channels • gates are regulated by membrane voltage • Chemical-Gated Ion Channels (also called Receptors) • gates are regulated by neurotransmitters • Iontotropic • fast • Metabotropic (G-protein coupled) • requires second messenger cascade • slow

  4. Chemical-Gated Ion Channels Iontotropic Metabotropic

  5. Electrochemical Gradient • Inside the Cell • More K+ • Less Na+ • Outside the Cell • More Na+ • Less K+ • Ion Flow Mantra: Na+ In, K+ out

  6. Depolarization/Hyperpolarization

  7. 2 Action Potential Phases Rapid 3 1 Threshold 4 Phase Ion responsible Ion Channel Responsible 1. Threshold Na+ Chemical-gated Na+ channel 2. Rapid Depolarization Na+ Voltage-gated Na+ channel 3. Repolarization K+ Voltage -gated K+ channel 4. After Hyperpolarization K+ Na+/K+ pumps

  8. Na+/K+ Pumps After the Action Potential, Na+/K+ pumps move Na+ ions back out of the cell and move K+ ions back into the cell The movement is against the concentration gradient of each ion so it requires energy (ATP) The pumps move 3 Na+ ions for every 2 K+ ions

  9. Unmyelinated Propagation

  10. Myelinated Propagation

  11. Synaptic Action Voltage-gated Ca2+ channels • Synaptic Potentials: • EPSP • IPSP

  12. Synaptic Potentials • Excitatory Postsynaptic Potential (EPSP) • triggered by excitatory neurotransmitters • open ligand-gated Na+ channels • allows Na+ to flow inside the cell • causing a slight depolarization of the postsynaptic cell • moves the postsynaptic cell closer to firing an action potential • Inhibitory Postsynaptic Potential (IPSP) • triggered by inhibitory neurotransmitters • open ligand-gated K+ channels or Cl- channels • allows K+ to flow out of the cell or Cl- to flow inside the cell • causing a slight hyperpolarization of the postsynaptic cell • moves the postsynaptic cell further from firing an action potential

  13. The Battle to -55mV IPSP EPSP

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