Bellringer: Water Intoxication What is hyponatremia? Symptoms? What is brain edema? What can it lead...
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Transcript of Bellringer: Water Intoxication What is hyponatremia? Symptoms? What is brain edema? What can it lead...
Bellringer: Water Intoxication
• What is hyponatremia?• Symptoms? • What is brain edema? • What can it lead to? • What is vasopressin and what does it do?
• 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
Action Potentials
• Neuron’s signaling device• Brief reversal of membrane potential• Excitable membranes only – nerve and muscle• SODIUM!
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”
Role of myelin
Saltatory Conduction
• “leaping/jumping” electrical signal • Current can only pass through the membrane at the nodes, myelin
insulates• Dramatically increases speed of signal
No sodium entry – no action potential• Alcohol• Sedatives• Injected anesthetics block nerve impulses by reducing membrane permeability to ions
Cold and continuous pressure
• Interrupt blood circulation to neuronal processesImpair ability to conduct impulses
Ice to numbFoot goes “to sleep” when you sit on it
Exit Slip: What is multiple sclerosis? Impacts? • http://www.youtube.com/watch?v=qgySDmRRzxY