Question

imagine the two test tubes contain 10 ml’s of mary’s centrifuged blood. one from the first test and one from the second test. select the correct test for each beaker. next, answer the questions below.

1. what made mary’s hematocrit drop so drastically from the first results to the second? (highlight one)

a. mary received a lot of saline and increased her plasma content dramatically.
b. mary continued to lose blood from her injuries.
c. marys blood pressure dropped causing a drop in her hematocrit.
d. mary did not receive enough saline to help increase the red blood cell count.

1. what would have been the best treatment for replacing mary’s excessive blood loss without dropping her hematocrit levels? (highlight one)

a. infusion of more saline
b. infusion of white blood cells only.
c. infusion of whole blood.
d. infusion of red blood cells only.

1. why did you select this option?

Explanation:

Question 1

To determine why Mary's hematocrit dropped, we analyze each option:

• Option A: Saline increases plasma (liquid part of blood), diluting red blood cells (RBCs), so hematocrit (RBC volume %) drops. But the test tubes show less RBC in Test 2, suggesting blood loss, not dilution.
• Option B: Continuing blood loss reduces total RBC (since blood loss includes RBCs), so hematocrit (RBC/total blood volume) drops. This matches the test tube observation (Test 2 has less RBC than Test 1).
• Option C: Blood pressure drop doesn’t directly cause hematocrit to drop; hematocrit is about RBC concentration, not pressure.
• Option D: Saline doesn’t increase RBC count; it dilutes. So this is incorrect.

So the correct answer is B as blood loss reduces RBC, lowering hematocrit.

To replace blood loss without dropping hematocrit, we need to replace both RBCs and plasma (since hematocrit is RBC/total blood volume).

• Option A: Saline (plasma-like) dilutes RBCs, lowering hematocrit.
• Option B: White blood cells (WBCs) don’t replace RBC loss, so hematocrit would still drop (since RBCs are lost, and WBCs don’t contribute to hematocrit).
• Option C: Whole blood contains RBCs, WBCs, plasma, etc. Replacing with whole blood restores total blood volume and RBC count, so hematocrit (RBC/total) stays stable.
• Option D: RBCs alone would increase RBC count but not plasma, so total blood volume might not be restored, and hematocrit could rise (but the goal is to replace blood loss, which includes plasma). Whole blood is better as it replaces all components.

Thus, whole blood (Option C) is best.

Whole blood contains red blood cells (RBCs), plasma, and other blood components. Mary lost whole blood (both RBCs and plasma). Infusing whole blood replaces both the lost RBCs (to maintain their concentration/hematocrit) and the lost plasma (to restore blood volume).

• Saline (Option A) only replaces plasma, diluting RBCs (lowering hematocrit).
• WBCs (Option B) don’t replace RBC loss, so hematocrit drops.
• RBCs alone (Option D) don’t replace plasma, so blood volume might not be fully restored, and hematocrit could become too high or not address plasma loss.

Whole blood matches the composition of lost blood, so it maintains hematocrit while replacing volume.

Answer:

B. Mary continued to lose blood from her injuries.

Question 2