PHYS 1525 Final Exam Review - Respiratory

PHYS 1525 Final Exam Review - Respiratory - Respiratory...

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Respiratory Unit: Where gaseous exchanges take palace. 300 million alveoli allow there to be around 750 square feet of surface area available for gas exchange. The Respiratory Unit Respiratory Membrane: The surface of the epithelium (inside the alveolus) and the respiratory capillary. The surface of the epithelium is covered by water and surfactant. 1. There is a very short diffusion distance (shown below). Anything that causes edema in the lungs affects this distance and subsequently compromises lung function. 2. Congestive heart failure: Capillary blood pressure in the capillaries of the alveolus increases and more fluid is filtered into the interstitial space. This resultant edema now makes the diffusion distance wider, and thus this interferes with gas exchange. Gaseous Exchange There are different cell types: a. Type I: Most of the alveolus cells; the basic structural cells. b. Type II: Produce pulmonary surfactant. c. There are also microphages in the alveolus. Surfactant: This substance decreases the surface tension of the water at the epithelial membrane. 1. When you breathe in, the alveoli (lined with water and surfactant) must get bigger. To do this, you must overcome the surface tension of the water inside of the alveolus. Surfactant lowers this surface tension and makes it more feasible to do so. 2. Surfactant also has a role in alveolar stability: a. There is a relationship between the pressure in the sphere (alveoli) and the surface tension. b. P = (2T)/r T = surface tension r = radius of alveoli P = pressure c. As r gets smaller the pressure increases. The smaller alveoli thus would collapse into the bigger alveoli. d. Surfactant prevents this by creating more stability in the alveoli. I. 1. IRDS (Infant Respiratory Distress Syndrome): In general, surfactant appears late in a fetus’ life because it does not need to breathe until it is born (pulmonary structures and surfactant are fully functional around 34 weeks). a. In premature infants (or with a mother who has diabetes mellitus or other pathology), there is not sufficient surfactant produced and the infant has a great deal of trouble breathing. This can lead to death.
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b. Treatment: Artificial surfactant can be administered through a tube or a breathing apparatus can be put in to force air in the lungs. 2. ARDS (Adult Respiratory Distress Syndrome): There is a different etiology involved than with IRDS. Also known as “wet lung” or “shock lungs”, 50% of the people with ARDS die even with medical treatment. The exact cause is not known, but thus far it is believed that it is due to some disturbance in the pulmonary capillaries: a. The pulmonary capillaries become very permeable to fluid (because of near drawings (water in the lungs), reactions to toxins, certain surgeries (heart bypass), or infections from pneumonia or TB). b. The resultant leakage of proteins into interstitium causes a
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This note was uploaded on 11/22/2011 for the course PHYS 1525 taught by Professor Lescane during the Winter '11 term at Life Chiropractic College West.

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PHYS 1525 Final Exam Review - Respiratory - Respiratory...

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