Lect29 - Feb18 - resp IV and renal I

Lect29 - Feb18 - resp IV and renal I - O2 diuses down a PP...

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Topic #2 Respiration 26 Some Questions on the Oxyhemoglobin Dissociation Curve 0 2 4 6 8 10 12 14 16 18 20 0 10 20 30 40 50 60 70 80 90 100110120130 Po2 Torr O2 Content ml O2/100 ml Blood Decrease O2 content by 2 ml. Decrease O2 Content by 2 ml. What are the contributions of dissolved & Hb bound sources of oxygen when content decreases from 20 to 18 ml? Why is the change in partial pressure for oxygen so much greater with a decrease in content from 20 to 18 compared to 14 to 12 ml? What are the contributions of dissolved & Hb bound sources of oxygen when content decreases from 14 to 12 ml? O2 di f uses down a PP gradient. The PP gradient determines how much di f uses. As O2 di f uses from it's dissolved state into the tissues, the PO2 of the blood decreases, thus decreasing the PP gradient for di f usion. The decrease in PO2 is bu f ered by Hb. As the PO2 falls, Hb releases O2, but Hb releases O2 at di f erent rates depending on the PO2 of the blood = Hb's a F nity for O2 changes depending on the PO2 of the blood. The more readily Hb releases O2, the slower the fall in PO2. The time it takes for blood to Fow though the capillaries is on the order of 1/2 second, so di f usion must happen very quickly. 1) there is a 2ml decrease in O2 content from 20ml to 18ml --> PO2 falls from 100 to 60 Torr. As O2 di f uses from the dissolved state out into the tissues, the amount of O2 dissolved decreases --> Hb bu f ers the drop in PO2 very little because it's a F nity for O2 is still very high. 2) there is a 2ml decrease in O2 content from 14ml to 12ml --> PO2 falls from 38 to 33 Torr. Only a 5 Torr di f erence. Hb's a F nity for O2 is much less at this PO2, so it more readily gives up O2. the amount dissolved is much less. As O2 leaves the blood, the PO2 < 60 Torr, Hb gives up O2 and this bu f eres the decrease - slows the fall in dissolved O2 and thus slows the fall in PO2. ENHANCES DI±±USION O± O2 INTO THE TISSUES. 1 2

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1/26/11 28 Topic #2 Respiration 27 Model Showing Hemoglobin’s Buffering of Dissolved Oxygen and the Partial Pressure of Oxygen as Oxygen Content Decreases
1/26/11 29 Respiration 21 Outline Topic #3 1. Chemical Control of Ventilation – Peripheral and Central Chemoreceptors. 2. Central Neural Control of Ventilation – Medullary, Midbrain, & Cortical Control. Hering- Breuer (Inspiratoinhibitory) Reflex You are responsible for covering this material on your own.

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1/26/11 30 Topic #3 Respiration 29 Chemical and Central Neural Control of Respiration Fig. 13-33 & 13-34 Chemical Control 1. Peripheral Chemoreceptors Carotid Bodies & Aortic Bodies 2. Central Chemoreceptors – Two populations in Brainstem Adjacent to the 4 th Ventricle & influenced by BBB Population neurons in Brainstem adjacent to permeable capillaries ( permeable gases and ions ) 3. Effective Stimulus at chemosensitive cells Po2 H+ Central Neural Control – Brain Stem + Higher Areas Generation of Basic Breathing Rhythm in Medullary Respiratory and Expiratory Neuron Groups.
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This note was uploaded on 08/21/2011 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.

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Lect29 - Feb18 - resp IV and renal I - O2 diuses down a PP...

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