Term
| What happens to the shape of the diaphragm as it contracts? |
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Definition
| It shortens and flattens, increasing the volume of the thorax. |
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Term
| What substantial structure separates the two lungs? |
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Definition
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Term
How many "generations" or levels exist in the lungs?
In which levels does gas exchange take place? |
|
Definition
23
The last four generations of airways; 20-23 |
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Term
| What is the approximate number of alveoli in the lungs? |
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Definition
|
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Term
| What is the approximate geometry of individual alveoli? |
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Definition
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Term
| What is the pproximate diameter of alveoli? |
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Definition
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Term
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Definition
| Essentially flat, basically a meshwork of capillaries. |
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Term
What are anastomoses?
What is their function? |
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Definition
Connections between bronchial and pulmonary capillaries
Usually little function in healthy adults; may open in pathological conditions, such as when blood flow is blocked to a portion of the lung |
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Term
| What is the diffusion distance for gases to move from the alveolar space to erythrocytes? |
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Definition
|
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Term
| Describe diffusion time for gases. |
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Definition
| Very short, almost instantaneous |
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Term
| What is the pathway from alveolus to erythrocyte in gas exchange? |
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Definition
| Alveolar epithelium -> interstitial space -> endothelial cells -> plasma -> erythrocyte |
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Term
| What is the pressure of the atmosphere at sea level? |
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Definition
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Term
What percentage of barometric pressure is exerted by O2 vs. N2 molecules?
What are their partial pressures? |
|
Definition
21% O2
79% N2
PO2 = 0.21 * 760 = 160mmHg
PN2 = 0.79 * 760 = 600mmHg |
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Term
| What is the conversion between mmHg and cm H20? |
|
Definition
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Term
| What is the partial pressure of water vapor at body temperature? |
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Definition
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