chapter 5

Question 1

1. Which of the following is an erythroid progenitor?
   a. Pronormoblast
   b. Reticulocyte
   c. CFU-E
   d. Orthochromic normoblast

Answer 1

c. CFU-E

Question 2

2. Which of the following is the most mature normoblast?
   a. Orthochromic normoblast
   b. Basophilic normoblast
   c. Pronormoblast
   d. Polychromatic normoblast

Answer 2

a. Orthochromic normoblast

Question 3

3. What erythroid precursor can be described as follows: The cell is of medium size compared with other normoblasts, with an N:C ratio of nearly 1:1. The nuclear chromatin is condensed and chunky throughout the nucleus. No nucleoli are seen. The cytoplasm is gray-blue.
   a. Reticulocyte
   b. Pronormoblast
   c. Orthochromic normoblast
   d. Polychromatic normoblast

Answer 3

d. Polychromatic normoblast

Question 4

4. At which normoblastic stage does globin production begin?
   a. Orthochromic normoblast
   b. Pronormoblast
   c. Polychromatic normoblast
   d. Basophilic normoblast

Answer 4

b. Pronormoblast

Question 5

5. Hypoxia stimulates RBC production by:
   a. Inducing more pluripotent stem cells into the erythroid lineage
   b. Stimulating EPO production by the kidney
   c. Increasing the number of RBC mitoses
   d. Stimulating the production of fibronectin by macrophages of the bone marrow

Answer 5

b. Stimulating EPO production by the kidney

Question 6

6. Erythropoietin can increase the production of RBCS by:
   a. Promoting apoptosis of erythroid progenitors
   b. Decreasing intravascular hemolysis
   c. Increasing EPO receptor sites
   d. Promoting early release of reticulocytes from bone marrow

Answer 6

d. Promoting early release of reticulocytes from bone marrow

Question 7

7. In the bone marrow, erythroid precursors are located:
   a. Surrounding macrophages in erythroid islands
   b.Adjacent to megakaryocytes along the adventitial cell lining
   c. Surrounding fat cells in apoptotic islands
   d. In the center of the hematopoietic cords

Answer 7

a. Surrounding macrophages in erythroid islands

Question 8

8. Which of the following determines the timing of egress of RBCs from the bone marrow?
   a. Stromal cells decrease production of adhesive molecules over time as RBCs mature.
   b. Endothelial cells of the venous sinus form pores at
   specified intervals of time, allowing egress of free cells.
   c. Periodic apoptosis of pronormoblasts in the marrow cords occurs.
   d. Maturing normoblasts slowly lose receptors for adhesive molecules that bind them to stromal cells.

Answer 8

d. Maturing normoblasts slowly lose receptors for adhesive molecules that bind them to stromal cells.

Question 9

9. What single feature of normal RBCs is most responsible for
   limiting their life span?
   a. Loss of the nucleus
   b. Increased flexibility of the cell membrane c. Reduction of hemoglobin iron
   d. Loss of mitochondria

Answer 9

a. Loss of the nucleus

Question 10

10. Extravascular hemolysis occurs when:
    a. RBCs are mechanically ruptured
    b. RBCs extravasate from blood vessels into the tissues
    c. Splenic macrophages ingest senescent RBCs
    d. RBCs are trapped in blood clots outside the blood vessels

Answer 10

c. Splenic macrophages ingest senescent RBCs