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

8. Types of Neurons

9. Supporting Cells = Neuroglia

10. Schwann Cells

12. Neural Pathways Example

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

15. 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

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

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

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

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

22. 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

23. Changes in Membrane Potentials

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

25. Graded Potentials Can be depolarizing event or hyperpolarizing event

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

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

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