1. 2 October 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 is posted to Website.

2. Survey (not graded) Name at the top edge, front side
1,2,3 Most important “take home messages” or most interesting facts or observations from this week’s lab on Andro paper, publication process including peer review, evaluation of sources.
Biggest concern about upcoming test.

3. 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.

4. Refractory period assures unidirectional conduction
Saltatory Conduction
Refractory period assures unidirectional conduction
Figure 6.23
AP CV (up to 100 m/s)
Location of channels
Energy Requirements
Axon diameter
Reminder: influx of Na+ is very quickly followed by efflux of K+ (not shown above)

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

6. Important Information

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

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

9. 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)

10. Types of Ligand-Gated Receptors
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.

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

12. 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.