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Lecture 8

KNES 323 Lecture Notes - Lecture 8: Central Chemoreceptors, Respiratory Center, Peripheral Chemoreceptors

Course Code
KNES 323
Carol Gibbons Kroeker

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Gas Exchange
-Occurs at pulmonary and systemic capillaries
-Depends on surface area, solubility, membrane thickness, diffusion distance,
concentration gradient (MOST important).
Partial Pressures:
- (Atmospheric pressure) x (composisiton)
-Majority of air (~79%) is nitrogen, the rest is oxygen, CO2, and other randoms.
Gas Laws:
P.gas = P.atm x % of gas in atmosphere
-CO2 and O2 pressures in blood….
Movement of gases:
-Mainly dependent on pressure gradient and solubility
-Temp also a factor.
Causes of Low Alveolar Oxygen Pressure:
-Low oxygen content in air (altitude)
-Alveolar ventilation is inadequate. (Low lung compliance, high resistence)
-Hypoxic hypoxia- low arterial oxygen pressure. High altitude
-Anemic hypoxia- low amount of oxygen bound to Hb.
-Ischemic hypoxia-…
-Histotoxic hypoxia-...
Gas Exchange:
-Oxygen diffuses across alveolar epithelial cells and capillary endothelial cells to
enter blood plasma
Pathological changes:…
Oxygen Transport:
-Hb increases oxygen transport in blood.
Hemoglobin: 4 subunits, each centered around Fe.
Oxygen-Hemoglobin Dissociation Curve:
-Slide 15 for graph/curve
-Larger oxygen pressure (like that in the alveoli) have a very high Hb saturation %.
-Hb saturation decreases at an accelerated rate as oxygen pressure drops.
-Physiological factors such as high temp or exercise shit the curve to the right, which
is good because it represents a greater ability to unload and use the oxygen.
-Oxygen is still consistently loaded, but the dissociation and use rate increases.
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