Term
| If PO2 is low, what does that mean? |
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Definition
| lower concentration of oxygen in the air = lower oxygen partial pressure |
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Term
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Definition
| concentration of oxygen in the air (PO2) |
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Term
| Why is PO2 of inspired air lower than environmental air? |
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Definition
| because it gets humidified, and the added water vapour 'dilutes' the oxygen concentration |
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Term
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Definition
| alveolar partial pressure of carbon dioxide |
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Term
| Why is alveolar oxygen tension (PA O2) lower than that of inspired air? |
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Definition
| because oxygen is diffusing out of the alveoli into the blood, and CO2 is diffusing in |
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Term
| If PA CO2 rises, what happens to PA O2? |
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Definition
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Term
| What is alveolar hypoventilation? |
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Definition
| decrease in ventilation of the alveoli, resulting in an increased PA CO2 and decreased PA O2 |
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Term
| What effect does alveolar hyperventilation have on PA CO2 / PA O2? |
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Definition
| increased ventilation will mean more CO2 is removed from the blood than is being produced, so PA CO2 will decrease while PA O2 increases |
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Term
| Will hypoxia lead to hypo or hyper ventilation? |
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Definition
| hyper (lack of oxygen will increase breath per minute to try and compensate) |
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Term
| Is gas exchange active or passive? |
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Definition
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Term
| What factors affect diffusion of gases across the alveolar & endothelial walls? |
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Definition
Diffusion coefficient of the gas
Surface area available for diffusion
Distance between air and blood
Pressure gradient |
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Term
| Why does gas exchange between capillaries & tissues improve during exercise? |
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Definition
| More capillaries are recruited, reducing the distance between tissues & capillaries and as the number of dilating vessels increases, blood flow slows which allows more time for gas exchange |
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Term
| What causes 'normal' ventilation mistmatch? |
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Definition
Gravity's effects on perfusion
-ventral areas have a lower V/Q than dorsal areas |
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Term
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Definition
| ventilation/perfusion ratio |
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Term
| What is 'normal' V/Q in animals? |
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Definition
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Term
| What does a low V/Q mean? |
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Definition
| blood is circulating but not becoming fully oxygenated |
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Term
| What does a low V/Q mean? |
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Definition
| the alveolus is well ventilated but not receiving enough blood |
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Term
| Impaired ventilation is associated with (high/low) V/Q ratios |
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Definition
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Term
| What type of problem can be addressed by providing oxygen, ventilation or perfusion? |
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Definition
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Term
| What is a right-to-left shunt |
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Definition
| When blood flows through an unventilated region of the lung (or bypasses the lung completely) and picks up no O2 |
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Term
| Impaired perfusion is associated with (high/low) V/Q ratios |
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Definition
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Term
| If ventilation is normal but blood flow in the lungs is impaired, PO2 will be (high/low), while PCO2 will be (high/low) |
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Definition
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