BIO 203 Lecture 23

BIO 203 Lecture 23 - Lecture 23 4/24/07 Breath-hold diving...

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Lecture 23 4/24/07 Breath-hold diving Shallow water blackout Sudden loss of consciousness Strikes most commonly within 15 feet of the surface Occurs without warning Amnesia associated Hyperventilation in the diver, get more oxygen and then get rid of carbon dioxide Blows up much more CO2 as well Diver got rid of additional CO2, but did not gain much more oxygen at all Peripheral chemoreceptors, in rest of body, as opposed to central, in brain or spinal cord Mammals – carotid body and aortic arch are the receptors in mammals, activated by decreases in O2 and increased CO2 partial pressures He decreased so much CO2 while he hyperventilated that the chemoreceptors did not have a chance to detect the amount of CO2 to the diver that he needed to breath and so suddenly got unconscious Peripheral stretch receptors Hering-Breuer Reflex Inspiration activates stretch receptors in bronchi and bronchioles…. Rest of slide Central chemoreceptors o Mammals and other air breathing vertebrates o Located in medulla oblongata o Stimulated by a decrease in pH of cerebral spinal fluid CSF o Very sensitive Has to get past blood brain barrier, lack fenestrations (like windows or holes in capillaries), lack in brain capillaries, things like proteins and RBCs are less likely to get through from the capillary into the brain Ordinarily these fenestrations would provide an aqueous path that charged ions could get through Charged ions cannot travel through cell membrane because they are charged and need aqueous pores in order to get through Brain lacks these pores, so charged molecules cannot get through Sensitive to pH, hydrogen ion concentration, a charged particle, cannot get through the blood brain barrier Gases, oxygen and carbon dioxide are the ones that can diffuse through this barrier
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This note was uploaded on 04/08/2008 for the course BIO 328 taught by Professor Cabot during the Spring '07 term at SUNY Stony Brook.

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BIO 203 Lecture 23 - Lecture 23 4/24/07 Breath-hold diving...

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