Term
| How thick is the alveolocapillary membrane? What is the total alveolocapillary membrane surface area? |
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Definition
alveolocapillary membrane = 0.2-0.3 um
surface area = 50 to 100 m2 |
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Term
| What is the net gradient for nitrogen to diffuse in the lungs/capillaries? |
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Definition
| there is no net gradient for N2 to diffuse across the interface because we neither produce nor consume N2 |
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Term
| What is the partial pressure of oxygen in the lung? in deoxygenated blood? |
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Definition
lung = 100 mmHg
venous blood = 40 mmHg |
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Term
| what are characteristics of bronchioles? |
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Definition
| smooth muscle but no cartilage, very flexible |
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Term
| Where is the region for airway resistance control? |
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Definition
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Term
| how many times does the lung branch? |
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Definition
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Term
| What is airway generation 0 of the lungs? |
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Definition
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Term
| What is airway generation 1 of the lungs? |
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Definition
| L and R mainstream bronchi |
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Term
| What are airway generations 2-3 of the lungs? |
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Definition
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Term
| what airway generation are the terminal bronchioles? |
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Definition
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Term
| What characterizes airway generations 17 to 19? What name is given to these divisions? |
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Definition
| Airway generations 17 to 19 (respiratory bronchioles) have scattered alveoli and comprise the transitional zone. Gas can exchange with the blood only in places where alveoli are present. |
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Term
| What airway generations are the alveolar ducts? |
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Definition
| Airway generations 20 to 22 |
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Term
| What is airway generation 23 (or the last generation)? |
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Definition
| alveolar sacs -- they have alveoli in all directions supporting rich gas exchanges with the blood. |
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Term
| What is the volume of the airway conduction zone? |
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Definition
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Term
| What is the volume of the airway respiratory zone? |
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Definition
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Term
| What makes up the blood-gas interface? |
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Definition
| the capillary endothelium and alveolar epithelium separated by an ultra-thin interstitium |
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Term
| How thick is the pulmonary capillary diameter? |
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Definition
pulmonary capillary diameter = 7 to 10 um
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Term
| What is the pressure in the pulmonary vascular system? What is the pulmonary vascular resistance? |
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Definition
pulmonary vascular pressure = 20 mmHg
pulmonary vascular resistance = 4 mm Hg/(L/min) |
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Term
| What is the difference between Type I and Type II pneumocytes? |
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Definition
| Type I forms the thin alveolocapillary membrane Type II secretes surfactant and is bigger |
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Term
| How many alveoli does the human lung have? what is their average diameter? |
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Definition
| 500 million alveoli with an average diameter of 0.3 mm. |
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Term
| What two factors keep alveoli open? |
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Definition
| 1. The negative intrapleural pressure pulls on the surface of the lung and each alveolus pulls on its neighbor to the deepest part of each lung lobe. 2. the presence of alveolar surfactant floating on the water layer of the alveolar epithelium decreases the air-water surface tension forces. |
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Term
| What size of particles are able to diffuse across the alveolar membrane? |
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Definition
| particles less than 0.1 um |
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Term
| How do the characteristics of the airway walls change as you descend from the trachea/bronchi to bronchioles to alveoli? |
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Definition
trachea/bronchi have goblet cells, cartilage, smooth muscle, epithelium, cilia
bronchioles have smooth muscle, epithelium, cilia
alveoli only have membrane and single layers epithelium/endothelium |
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Term
| since there are no cilia in the aveoli, how are unwanted particles removed? |
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Definition
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Term
How long do RBCs spend in the gas exchange zone?
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Definition
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