Ed Rivers, a 3rd year medical student, was alone in the hospital ER one night. It was unusually quiet that night, and the resident was getting some much needed sleep. A patient, Mrs. X, was brought in showing signs of serious dehydration. Ed tried to give her water, but she vomited this back up. Feeling he must try something, and not wanting to wake the resident, Ed administered 1 liter of sterile distilled water IV. Assume for simplicity that the red blood cells contain only solutes to which the rbc membrane is impermeable, and that the rbcs and plasma are in osmotic equilibrium when the patient is brought in. The osmolarity of the rbc is 300 mOsm/L.The volume of Mrs. Xâs plasma was 3 liters before Ed administered the IV.
Had Ed given Mrs. X a sucrose solution instead of water, he might have helped her. What concentration of sucrose solution should he have administered to leave her rbc volume unaffected, and why?
Ed Rivers, a 3rd year medical student, was alone in the hospital ER one night. It was unusually quiet that night, and the resident was getting some much needed sleep. A patient, Mrs. X, was brought in showing signs of serious dehydration. Ed tried to give her water, but she vomited this back up. Feeling he must try something, and not wanting to wake the resident, Ed administered 1 liter of sterile distilled water IV. Assume for simplicity that the red blood cells contain only solutes to which the rbc membrane is impermeable, and that the rbcs and plasma are in osmotic equilibrium when the patient is brought in. The osmolarity of the rbc is 300 mOsm/L.The volume of Mrs. Xâs plasma was 3 liters before Ed administered the IV.
Had Ed given Mrs. X a sucrose solution instead of water, he might have helped her. What concentration of sucrose solution should he have administered to leave her rbc volume unaffected, and why?
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