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Old 08-19-2011
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Lungs Cells capable of gas exchange!

A physiologist has created an in vitro replication of the human lung and is in the process of designing the component responsible for gas exchange. He wants to design a product that is most similar to human alveolar sacs and can efficiently exchange O2 and CO2. Which of the following must be a part of his design plans?
A. Cells that can replicate when exposed to damage
B. Phagocytic cells that release inflammatory cytokines
C. Cells that secrete pulmonary surfactant
D. Columnar cells with secretory granules
E. Squamous cells that form tight junctions
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Old 08-19-2011
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c) cells must produce surfactant to be able to get oxygen (keep area surface)
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Old 08-19-2011
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Im not really sure about this though. squamous cells that make the tight junctions could be pneumocyte I which does gas exchange. To my knowledge they make up the gas exchange barrier so i guess they make the tight junction as well. I pick C because in the question stem it says 'efficiently' which surfactant will help by decreasing the surface tension.
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Old 08-19-2011
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A physiologist has created an in vitro replication of the human lung and is in the process of designing the component responsible for gas exchange. He wants to design a product that is most similar to human alveolar sacs and can efficiently exchange O2 and CO2. Which of the following must be a part of his design plans?
A. Cells that can replicate when exposed to damage= Type II Pneumocytes
B. Phagocytic cells that release inflammatory cytokines
C. Cells that secrete pulmonary surfactant= Type II Pneumocytes
D. Columnar cells with secretory granules
E. Squamous cells that form tight junctions= Type I Pneumocytes
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Old 08-21-2011
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The correct answer is E.
The physiologist is designing cells that are most similar to Type I pneumocytes. He needs cells that can participate in diffusion of gasses, and thus needs thin squamous cells forming tight junctions, as type I pneumocytes do in the lining of the alveolus.

Type II pneumocytes secrete pulmonary surfactant and replicate to form both type I and II pneumocytes when damaged. Columnar cells with secretory granules are Clara cells. They secrete proteins that inhibit neutrophil recruitment and activation. Alveolar macrophages are phagocytic cells that release inflammatory cytokines that attract neutrophils when the lung is damaged.
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Cell-Biology-, Histology-, Physiology-, Respiratory-, Step-1-Questions

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