1. 26 September 2008 Finish Chapter 6 Section B Membrane Potentials
Begin Section C: Synapses
Test # 1 Monday (includes to Ch. 6B)
Start promptly at 8:30 am (Get here early!)
Test Study Guide to be posted to Website.

2. Action Potential conduction in non-myelinated axons
Figure 6.22
Action Potential conduction in non-myelinated axons
(0.5 m/sec in small diameter unmyelinated axons)
Axon diameter and AP CV
Energy Requirements
Changes in concentration of Na+ and K+ only with long lasting period of high frequency action potentials.
Initial experiments with squid giant axon (1mm diameter) lead to knowledge of APs.

3. AP CV (up to 100 m/s) Location of channels Energy Requirements
Figure 6.23
AP CV (up to 100 m/s)
Location of channels
Energy Requirements
Axon diameter

4. Who Cares?
Multiple sclerosis and episodic degeneration of myelin by immune disorder.

5. Important Information

6. End of Material For Test # 1
Begin Material For Test # 2

7. Figure 6.24
Two categories of Synapses: Electrical (rare in nervous system) & Chemical

8. Figure 6.25 Unidirectional Release, diffusion, binding,
Post-synaptic Receptor Types: Inotropic or Metabotropic
Figure 6.25
Classification:
Excitatory (closer to threshold for AP) Or
Inhibitory (stabilizes or hyperpolarizes)

9. Inotropic receptor
Metabotropic receptor
Some ion channels are permeable to both Na+ and K+
Preview of coming attraction: the nicotinic Acetylcholine receptor so named for its agonist.

10. Synapses named for NT used: -ergic
Examples:
Cholinergic
Adrenergic
Serotonergic
Peptidergic

11. Vesicle release proportional to Ca++ influx
Figure 6.27
Fates of neurotransmitters:
1) Diffusion away from synapse,
2) Enzymatic degradation (e.g. AChE and MAO)
3) Reuptake into presynaptic terminal (SSRI)
Tetanus toxin & Botulinum toxin disrupt SNARE function.

12. Figure 6.28
EPSPs :which ion moving in which direction?
Duration of PSP vs AP
Synaptic delay
Ion Channels that allow flux of Na+ and K+ simultaneously.

13. IPSPs :which ion moving in which direction?
Figure 6.29
IPSPs :which ion moving in which direction?
Some IPSPs result in no change in membrane potential by opening Chloride channels that stabilize membrane potential at resting value or in cells that actively transport Cl- out.

14. Summation and Synaptic Integration
Figure 6.31
Summation and Synaptic Integration