PLEASE DO NOT COPY AN ANSWER THAT WAS ALREADY POSTED Ed Rive

PLEASE DO NOT COPY AN ANSWER THAT WAS ALREADY POSTED

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

1. Predict the direction (increase, decrease, no change) you would expect Ed’s infusion to have produced in these parameters, and explain your predictions in terms of what you know from lecture and lab.

a. Mrs. X’s plasma osmolarity after the infusion? Prediction: Why?

b. Mrs. X’s rbc volume after the infusion equilibrates with blood? Prediction: Why?

c. The osmolarity of the rbcs and plasma after equilibration, in relation to the initial state? Prediction: Why?

Solution

a. Mrs. X\'s plasma osmolarity after the infusion will decrease because when steril distilled water IV is infused into the patient, the plasma volume is expanded and the solutes present in the plasma is diluted.

b. the rbc volume will increase after the infusion equilibrates with blood because of the decrease in plasma osmolarity.

c. rbc osmolarity will decrease and the plasma osmolarity will increase, but the value will be varying from the inital stage.