Chapter 6: Erythrocyte Production and Destruction (30Q)

Which of the following is an erythroid progenitor?

CFU-E

Which of the following is the most mature normoblast?

Orthochromic normoblast

What erythroid precursor can be described as: medium size, N:C ratio nearly 1:1, nuclear chromatin condensed and chunky, cytoplasm gray-blue?

Polychromatic normoblast

At which normoblastic stage does globin production begin?

Pronormoblast

Hypoxia stimulates RBC production by:

Stimulating EPO production by the kidney

Erythropoietin can increase the production of RBCs by:

Promoting early release of reticulocytes from bone marrow

In the bone marrow, erythroid precursors are located:

Surrounding macrophages in erythroid islands

Which of the following determines the timing of egress of RBCs from the bone marrow?

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

What single feature of normal RBCs is most responsible for limiting their life span?

Loss of the nucleus

Extravascular hemolysis occurs when:

Splenic macrophages ingest senescent RBCs

Which stage of erythroid maturation is the last to undergo mitosis?

Polychromatic normoblast

Which organ produces the majority of erythropoietin in adults?

Kidney

What is the average lifespan of a normal RBC in peripheral blood?

120 days

Which stage of erythroid maturation first shows pink cytoplasm due to hemoglobin synthesis?

Polychromatic normoblast

What is the primary function of erythropoietin?

Stimulate proliferation and differentiation of erythroid progenitor cells

Which cells are the first morphologically identifiable erythroid precursors in bone marrow?

Pronormoblasts

Which organ is primarily responsible for RBC destruction under normal conditions?

Spleen

Reticulocytes differ from mature RBCs because they contain:

Residual RNA

Which RBC precursor has an N:C ratio of about 4:1, with fine chromatin and 1–2 nucleoli?

Pronormoblast

Which cytokine works synergistically with EPO in erythropoiesis?

Interleukin-3 (IL-3)

Which process allows RBC precursors to exit bone marrow into circulation?

Diapedesis through sinusoidal endothelium

Which organ contributes to extravascular hemolysis by filtering senescent RBCs?

Spleen

What major energy pathway maintains RBC membrane integrity?

Embden-Meyerhof pathway (glycolysis)

What is the main iron transport protein for hemoglobin synthesis?

Transferrin

Which morphological change occurs as RBC precursors mature?

Decrease in cell size and N:C ratio

Which factor inhibits apoptosis of erythroid progenitors during hypoxia?

Erythropoietin (EPO)

Which organ serves as a secondary site of RBC destruction if the spleen is absent?

Liver

How is bilirubin produced during RBC destruction?

From the breakdown of heme

Which feature differentiates orthrochromic normoblast from earlier stages?

Pyknotic nucleus ready for extrusion

Which test indicates increased erythropoietic activity in bone marrow?

Reticulocyte count