Blood Anatomy and Physiology Practice Questions

25 multiple-choice questions on Blood anatomy and physiology for paramedic and EMT students, from Chapter 25 (Hematologic Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A man reaches the ED 20 minutes after losing a large amount of blood from a leg wound. His first hematocrit is close to normal. The best explanation is that:

   1. A. The marrow has already replaced the lost cells
   2. B. Cells and plasma were lost together
   3. C. Hemorrhage concentrates the remaining blood
   4. D. The kidneys released extra erythropoietin
   Show answer

   Answer: B. Cells and plasma were lost together

   Whole blood is lost, so the ratio of cells to plasma stays about the same at first. The hematocrit falls over hours as fluid shifts into the vessels or IV fluid is given, so a normal early value does not rule out major hemorrhage. Marrow replacement and erythropoietin take days to have any effect.

2. After two days of vomiting and diarrhea, a patient has a hematocrit of 56%. The most likely reason is:

   1. A. New red cell production set off by fluid loss
   2. B. Polycythemia vera unmasked by the illness
   3. C. Loss of plasma water concentrating the cells
   4. D. Hemolysis releasing hemoglobin into plasma
   Show answer

   Answer: C. Loss of plasma water concentrating the cells

   Losing plasma water makes the same red cell mass a larger share of the blood (relative polycythemia), and it corrects with rehydration. New red cell production takes days, so it cannot explain a rise over two days, and hemolysis lowers the hematocrit rather than raising it.

3. Plasma is composed mostly of:

   1. A. Water
   2. B. Albumin
   3. C. Fibrinogen
   4. D. Glucose
   Show answer

   Answer: A. Water

   Plasma is about 92% water. The rest is proteins (albumin, globulins, fibrinogen), electrolytes, nutrients, hormones, and wastes.

4. Red cells stored for several weeks release oxygen poorly right after transfusion because they are low in:

   1. A. Hemoglobin
   2. B. Iron
   3. C. Albumin
   4. D. 2,3-DPG
   Show answer

   Answer: D. 2,3-DPG

   2,3-DPG inside red cells helps hemoglobin unload oxygen. Its level falls during storage, shifting the curve to the left, and recovers within a day or so after transfusion. Stored cells still contain normal hemoglobin and iron, and albumin is a plasma protein, not a red cell regulator.

5. A patient's lab report shows a hemoglobin of 10 g/dL. Her hematocrit is most likely about:

   1. A. 30%
   2. B. 10%
   3. C. 20%
   4. D. 50%
   Show answer

   Answer: A. 30%

   In most patients the hematocrit is roughly three times the hemoglobin, so 10 g/dL corresponds to about 30%. A hematocrit of 50% would match a hemoglobin near 17 g/dL.

6. All blood cells develop from:

   1. A. Mature circulating lymphocytes
   2. B. Pluripotent stem cells
   3. C. Splenic macrophages
   4. D. Hepatic stem cells
   Show answer

   Answer: B. Pluripotent stem cells

   A single type of marrow stem cell gives rise to red cells, white cells, and platelets.

7. Iron absorbed from the gut is carried in the plasma bound to:

   1. A. Albumin
   2. B. Ferritin
   3. C. Erythropoietin
   4. D. Transferrin
   Show answer

   Answer: D. Transferrin

   Transferrin carries iron to the marrow and to storage sites. Ferritin is the storage form inside cells, albumin carries many drugs but not iron, and erythropoietin is a hormone, not a carrier.

8. The flexible biconcave shape of a normal red cell mainly allows it to:

   1. A. Divide to replace damaged red cells
   2. B. Store iron for later use
   3. C. Squeeze through narrow capillaries
   4. D. Attach to the walls of injured vessels
   Show answer

   Answer: C. Squeeze through narrow capillaries

   The thin disc gives a large surface for gas exchange and lets the cell bend through capillaries narrower than itself. Mature red cells have no nucleus and cannot divide, and sticking to injured vessel walls is the platelets' job.

9. A lab report shows a high share of immature band neutrophils. This most suggests:

   1. A. A chronic parasitic infection
   2. B. A severe allergic reaction
   3. C. An acute bacterial infection
   4. D. Iron deficiency anemia
   Show answer

   Answer: C. An acute bacterial infection

   During a bacterial infection the marrow releases neutrophils before they fully mature, a so-called left shift. Parasites and allergies raise eosinophils instead, and iron deficiency affects red cells, not neutrophil maturity.

10. A normal adult white blood cell count is about:

    1. A. 500 to 1,000/µL
    2. B. 1,000 to 2,000/µL
    3. C. 50,000 to 100,000/µL
    4. D. 5,000 to 10,000/µL
    Show answer

    Answer: D. 5,000 to 10,000/µL

    Counts above about 11,000/µL (leukocytosis) suggest infection, inflammation, stress, or a leukemia. Counts of 1,000/µL or less leave the patient open to serious infection, and counts near 100,000/µL occur mainly in leukemia.

11. Which white cells are classed as granulocytes?

    1. A. Lymphocytes, monocytes, macrophages
    2. B. Neutrophils, eosinophils, basophils
    3. C. B cells, T cells, natural killer cells
    4. D. Platelets, reticulocytes, megakaryocytes
    Show answer

    Answer: B. Neutrophils, eosinophils, basophils

    Granulocytes have visible granules in their cytoplasm. Lymphocytes and monocytes (which become macrophages) are agranulocytes, and platelets and reticulocytes are not white cells.

12. Platelet production in the marrow is stimulated mainly by:

    1. A. Thrombopoietin
    2. B. Erythropoietin
    3. C. Aldosterone
    4. D. Prothrombin
    Show answer

    Answer: A. Thrombopoietin

    Thrombopoietin, made mostly by the liver, drives platelet production. Erythropoietin drives red cell production, aldosterone controls sodium, and prothrombin is a clotting factor, not a growth signal.

13. Normal adult hemoglobin (hemoglobin A) is made of:

    1. A. Two alpha and two beta chains
    2. B. Four identical alpha chains
    3. C. Two alpha and two gamma chains
    4. D. One alpha and three beta chains
    Show answer

    Answer: A. Two alpha and two beta chains

    Each chain holds one heme group. Two alpha and two gamma chains make fetal hemoglobin, which is the main type before birth. Inherited disorders that change or reduce one type of chain cause chronic anemia.

14. A patient with a hemoglobin of 6 g/dL has an SpO2 of 82% but no visible cyanosis. The best explanation is that:

    1. A. The pulse oximeter is reading falsely low
    2. B. Too little hemoglobin is deoxygenated to show
    3. C. Anemic blood holds more dissolved oxygen
    4. D. Anemia shifts the oxygen curve well to the left
    Show answer

    Answer: B. Too little hemoglobin is deoxygenated to show

    Cyanosis needs roughly 5 g/dL of deoxygenated hemoglobin in capillary blood. A severely anemic patient may never reach that amount, so the absence of cyanosis does not mean oxygenation is adequate. Treat the low SpO2; do not wait for a color change. Dissolved oxygen is tiny at any hemoglobin level.

15. To bind oxygen, the iron in hemoglobin must be in which form?

    1. A. Ferric (Fe3+)
    2. B. Free iron in plasma
    3. C. Ferritin in the liver
    4. D. Ferrous (Fe2+)
    Show answer

    Answer: D. Ferrous (Fe2+)

    Oxidizing heme iron to the ferric form makes methemoglobin, which cannot carry oxygen. Oxidant drugs such as benzocaine or dapsone can cause it. Iron stored as ferritin or circulating free is not part of working hemoglobin.

16. A patient started on high-dose prednisone 3 days ago has a white count of 15,000/µL, no fever, and no signs of infection. The most likely explanation is that:

    1. A. The prednisone has caused acute leukemia
    2. B. Steroids make the marrow produce extra red cells
    3. C. The steroid has released stored neutrophils
    4. D. A hidden parasitic infection is present
    Show answer

    Answer: C. The steroid has released stored neutrophils

    Corticosteroids release neutrophils that normally cling to vessel walls, raising the count within hours. This is an expected effect, but keep assessing for infection, since steroids can also blunt fever. Steroids do not cause leukemia over days, and parasites raise eosinophils, which steroids actually lower.

17. Platelets are fragments of:

    1. A. Red blood cells
    2. B. Megakaryocytes
    3. C. Lymphocytes
    4. D. Macrophages
    Show answer

    Answer: B. Megakaryocytes

    Large marrow cells called megakaryocytes break apart to release platelets, which live about 7 to 10 days.

18. A normal platelet count is about:

    1. A. 5,000 to 10,000/µL
    2. B. 40,000 to 80,000/µL
    3. C. 900,000 to 1,200,000/µL
    4. D. 150,000 to 400,000/µL
    Show answer

    Answer: D. 150,000 to 400,000/µL

    Spontaneous bleeding becomes a risk when the count falls below about 20,000/µL.

19. Normal red cell production depends most on adequate supplies of:

    1. A. Calcium, vitamin D, and zinc
    2. B. Vitamin K, vitamin C, and sodium
    3. C. Iron, vitamin B12, and folate
    4. D. Potassium, iodine, and vitamin A
    Show answer

    Answer: C. Iron, vitamin B12, and folate

    Iron is built into hemoglobin, and B12 and folate are needed for the DNA synthesis of dividing marrow cells. A shortage of any of them causes anemia. Vitamin K is for clotting factors and calcium and vitamin D for bone.

20. After donating a unit of blood, a healthy adult restores the lost plasma volume within about:

    1. A. 1 to 2 days
    2. B. 1 to 2 hours
    3. C. 2 to 3 weeks
    4. D. 4 to 6 months
    Show answer

    Answer: A. 1 to 2 days

    Fluid shifts from the tissues and the kidneys conserve salt and water, so plasma volume returns within a day or two. Red cell mass takes much longer, several weeks, which is why donors must wait about 8 weeks between whole-blood donations.

21. Before a routine transfusion, the crossmatch tests:

    1. A. Recipient plasma against donor red cells
    2. B. Donor platelets against recipient platelets
    3. C. The donor unit for its hemoglobin level
    4. D. Recipient red cells against donor plasma
    Show answer

    Answer: A. Recipient plasma against donor red cells

    Mixing the patient's plasma with the donor's cells shows whether the patient has antibodies that would destroy them. In an emergency, uncrossmatched group O cells are given while this testing is done.

22. Most of the body's iron is found in:

    1. A. Ferritin stored in the spleen
    2. B. Iron-containing enzymes in the liver
    3. C. Iron bound to plasma albumin
    4. D. Hemoglobin in circulating red cells
    Show answer

    Answer: D. Hemoglobin in circulating red cells

    About two-thirds of body iron is in the hemoglobin of circulating red cells, so losing blood means losing iron. Ferritin stores in the liver, spleen, and marrow hold most of the rest.

23. Which formed element has the shortest life span in the circulation?

    1. A. Red blood cells
    2. B. Platelets
    3. C. Neutrophils
    4. D. Memory lymphocytes
    Show answer

    Answer: C. Neutrophils

    Neutrophils circulate for less than a day, platelets about 7 to 10 days, red cells about 4 months, and some memory lymphocytes for years. The short neutrophil life span is why marrow damage from chemotherapy shows up first as neutropenia.

24. A reticulocyte is:

    1. A. A type of white blood cell
    2. B. An immature red blood cell
    3. C. A platelet fragment
    4. D. A marrow fat cell
    Show answer

    Answer: B. An immature red blood cell

    A rising reticulocyte count shows the marrow is responding to blood loss or hemolysis.

25. A blood sample drawn with hard suction through a small catheter hemolyzes in the tube. Which lab result is most likely to be falsely high?

    1. A. Potassium
    2. B. Sodium
    3. C. Glucose
    4. D. Bicarbonate
    Show answer

    Answer: A. Potassium

    Red cells hold far more potassium than plasma, so cells bursting in the tube release it and the lab reports a falsely high level. Draw gently through an adequate catheter. Sodium, glucose, and bicarbonate are not raised by hemolysis to any important degree.