1. Bellringer: Water Intoxication What is hyponatremia? Symptoms? What is brain edema? What can it lead to? What is vasopressin and what does it do?

2. http://www.nbcnews.com/id/16614865/ns/us_news-life/t/woman- dies-after-water-drinking-contest/ http://www.nbcnews.com/id/16614865/ns/us_news-life/t/woman- dies-after-water-drinking-contest/ http://www.scientificamerican.com/article/strange-but-true-drinking- too-much-water-can-kill/?print=true http://www.scientificamerican.com/article/strange-but-true-drinking- too-much-water-can-kill/?print=true

3. Action Potentials Neuron’s signaling device Brief reversal of membrane potential Excitable membranes only – nerve and muscle SODIUM!

5. Propagation of the signal Sent/transmitted Local patch of axonal membrane Local current flows are established Depolarization of adjacent membrane areas – which way? Voltage-gated channels open, impulse is regenerated – self- propagating at a constant velocity Every action potential is identical “spread of local depolarizing currents”

8. Role of myelin

9. Saltatory Conduction “leaping/jumping” electrical signal Current can only pass through the membrane at the nodes, myelin insulates Dramatically increases speed of signal

10. No sodium entry – no action potential Alcohol Sedatives Injected anesthetics  block nerve impulses by reducing membrane permeability to ions

11. Cold and continuous pressure Interrupt blood circulation to neuronal processes  Impair ability to conduct impulses Ice to numb Foot goes “to sleep” when you sit on it

12. Exit Slip: What is multiple sclerosis? Impacts? http://www.youtube.com/watch?v=qgySDmRRzxY