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Electrical Signals 1

Electrical Signals 1. BIOL 1407. Electrical Signals. Changes in membrane potential  currents Used by cells for quick communication. Chemical vs. Electrical Signaling. Type of Signals Chemical Electrical + Chemical = Electrochemical Types of Chemicals Used Hormones Neurotransmitters.

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Electrical Signals 1

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  1. Electrical Signals 1 BIOL 1407

  2. Electrical Signals • Changes in membrane potential  currents • Used by cells for quick communication

  3. Chemical vs. Electrical Signaling • Type of Signals • Chemical • Electrical + Chemical = Electrochemical • Types of Chemicals Used • Hormones • Neurotransmitters

  4. Chemical vs. Electrical Signaling • Speed of Transmission • Slow • Fast • Duration of Response • Long • Short

  5. Functions of Nervous Systems

  6. Neuron • Cell body = Soma • Dendrites • Axon • Axon Hillock • Axon Terminals = Synaptic Knobs = Synaptic Terminals

  7. Types of Neurons

  8. Supporting Cells = Neuroglia

  9. Schwann Cells

  10. Neural Pathways Example

  11. Membrane Potential • Electrical Difference = Potential • Membrane at Rest = Resting Membrane Potential (RMP)

  12. Membrane Proteins • Sodium Potassium Pump • Maintains Resting Membrane Potential • Leak Channels • Na+ and K + Leak Channels • Chemically-Regulated (Gated) Channels • Also called Ligand-Gated Channels • Voltage-Regulated (Gated) Channels • Na+ and K + Voltage-Regulated Channels

  13. Chemically-Regulated Channels • Gated • On dendrites and cell body • Responds to chemicals • Graded potentials

  14. Voltage-Regulated Channels • Gated • On axons • Respond to changes in voltage • Action potentials (APs)

  15. Voltage-Regulated Na+ Channel Na+ Channel is Closed and Activated Na+ Channel is Closed and Inactivated Na+ Channel is Open; Stays Open for Short Amount of Time

  16. Voltage-Regulated K+ Channel K+ Channel is Closed K+ Channel is Open

  17. Changes in Membrane Potential • Resting Membrane Potential (RMP) • Depolarization • Membrane becomes more + than RMP • Hyperpolarization • Membrane becomes more – than RMP • Action Potential: pattern of MP changes • Depolarization • Repolarization • Undershoot: Brief Hyperpolarization

  18. Changes in Membrane Potentials

  19. Graded Potentials • Occur at dendrites and cell bodies • Response to changes in chemically-regulated channels • Strength diminishes over distance • Vary in strength

  20. Graded Potentials • Can be depolarizing event or hyperpolarizing event

  21. Action Potentials • Occur only along axons • Strength is always the same • Strength of signal stays the same along the entire length • All-or-none

  22. Threshold Stimulus • Threshold Stimulus – Enough depolarization to generate an AP • Usually -55 mV • Subthreshold Stimulus – Insufficient depolarization to generate an AP

  23. The End Unless otherwise specified, all images in this presentation came from: Campbell, et al. Biology, 7th ed. and 8th ed. Pearson Benjamin Cummings.

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