Term
Fick's Law of Diffusion
The rate of diffusion is proportional to the _______ & inversely proportional to the _______.
How does the partial pressure difference affect diffusion? |
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Definition
The rate of diffusion is proportional to the area & inversely proportional to the thickness.
Gas diffuses from higher pressure to lower pressure. |
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Term
The amount of carbon monoxide that gets into the blood is limited by the diffusion properties of the blood-gas barrier and not by the amount of blood available.
CO is therefore... |
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Definition
Diffusion limited.
This happens because CO is tightly bound to Hg in the RBC, preventing a big increase in capillary partial pressure. |
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Term
| The amount of gas taken up by the blood depends entirely on the amount of available blood, and not at all on the rate of diffusion. What type of gas exchange is this? |
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Definition
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Term
| Under what conditions is O2 diffusion-limited? |
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Definition
When the diffusion properties of the lung are impared.
(For example, thickening of the blood-gas barrier.) |
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Term
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Definition
| Amount dissolved is proportional to the partial pressure. |
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Term
| Normal arterial blood with PaO2 of 100 mmHg contains ______ blood. |
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Definition
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Term
| 1 gram Hb binds ______ O2. |
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Definition
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Term
| Hb bound O2 vs dissolved. |
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Definition
20 mL / dL
vs
0.3 mL / dL |
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Term
| Mixed venous oxygen saturation. |
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Definition
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Term
| Ideal person a-v difference. |
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Definition
Since 75% saturation, 15ml O2 / dL
20 - 15 = 5 |
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Term
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Definition
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Term
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Definition
| CaO2 = (Hb x SaO2 x 1.34) + (PaO2 x 0.003) |
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Term
What threshold must you reach before DO2 is insufficient and causes shock?
How does sepsis influence this? |
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Definition
66%
Sepsis makes the delivery worse, body consumes more at rest, shock reached easier. |
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Term
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Definition
| One can estimate cardiac output if one has the arterial and mixed venous blood gas and assumes VO2 to be 250 ml/min. |
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Term
Hemoglobin
PaO2 vs % saturation |
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Definition
100 mmHg = 97.5%
40 mmHg = 75%
26.5 mmHg = 50% (P50) |
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Term
| Right shift in the Hb dissociation curve is seen with... |
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Definition
Decreased pH
Increased PaCO2
Increased 2,3-DPG
Increased temperature |
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Term
| CO effect on O2 transport |
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Definition
It has 240x the affinity for Hb, so Hb binds much less oxygen.
It also causes a left shift in the curve, interfering with oxygen delivery. |
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Term
| Blood-Tissue gas exchange limitations |
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Definition
Diffusion limitation - increase distance from capillary to cell or decrease PaO2
Perfusion limitation - increase demand without increase in flow |
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Term
| How is carbon dioxide carried? |
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Definition
Dissolved - 10%
As bicarbonate - 60%
Combined with proteins - 30% |
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Term
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Definition
| RBC enzyme that creates carbonic acid from carbon dioxide and water. |
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Term
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Definition
Carbonic acid from RBC turns into H+ and bicarbonate. Bicarb diffuses out, but H+ cannot.
Cl comes into cell to maintain neutrality. |
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Term
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Definition
Reduced Hb in periphery helps loading of CO2.
Oxygenated Hb in the lung promotes unloading of CO2. |
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