RBC2

Question 1

What is erythropoiesis?

Answer 1

Formation of RBC

Erythropoiesis is the process of producing red blood cells (RBCs) in the body.

Question 2

What are the three main processes of blood cell formation?

Answer 2

• Erythropoiesis
• Thrombopoiesis
• Leucopoiesis

Question 3

What are the sites of erythropoiesis in a fetus?

Answer 3

• Mesoderm of yolk sac (0-2 months)
• Liver and spleen (2-7 months)
• Bone marrow (4-5 months onwards)

Question 4

Where does erythropoiesis occur in adults?

Answer 4

Bone marrow (red marrow) in vertebrae, ribs, sternum, pelvic bones, skull, proximal ends of femur and humerus

Question 5

What is the common site to obtain a sample of bone marrow?

Answer 5

Sternum or iliac crest

Question 6

What are the three types of stem cells involved in hematopoiesis?

Answer 6

• Pluripotent stem cells
• Myeloid stem cells
• Lymphoid stem cells

Question 7

What is the primary function of pluripotent stem cells?

Answer 7

Gives rise to any blood cells

Question 8

What do myeloid stem cells give rise to?

Answer 8

• RBC
• Platelets
• Granulocytes
• Monocytes

Question 9

What do lymphoid stem cells give rise to?

Answer 9

Lymphocytes (B and T cells)

Question 10

What are the two properties of all stem cells?

Answer 10

• Self-renewal
• Differentiation and commitment

Question 11

What are colony-forming units (CFU)?

Answer 11

Cells that arise from myeloid and lymphoid progenitors

Question 12

What are the two main lineages that arise from hematopoietic stem cells?

Answer 12

• Myeloid progenitor
• Lymphoid progenitor

Question 13

What type of progenitor cells are CFU-GEMM and CFU-E?

Answer 13

CFU-GEMM: Multipotent
CFU-E: Unipotent

Question 14

What is the earliest stage in the erythroid series?

Answer 14

BFU-E (Burst-forming unit – Erythrocyte)

Question 15

What is the role of erythropoietin (EPO)?

Answer 15

Stimulates RBC production in response to hypoxia

Question 16

What are essential factors for erythropoiesis?

Answer 16

• Iron
• Vitamin B12
• Folate

Question 17

What is the function of iron in erythropoiesis?

Answer 17

Essential for hemoglobin synthesis

Question 18

What are the stages of erythropoiesis?

Answer 18

• Pronormoblast
• Basophilic normoblast
• Polychromatophilic normoblast
• Ortochromic normoblast
• Reticulocyte
• Erythrocyte

Question 19

What happens to the nucleus during the maturation of erythrocytes?

Answer 19

It becomes pyknotic and is extruded

Question 20

What is the diameter of a mature erythrocyte?

Answer 20

7 to 8 µm

Question 21

What causes the secretion of erythropoietin?

Answer 21

Decreased tissue oxygenation (hypoxia)

Question 22

What are the consequences of vitamin B12 deficiency in erythropoiesis?

Answer 22

Failure of nuclear maturation and production of macrocytes

Question 23

Fill in the blank: The common site to obtain a sample of bone marrow for diagnostic purposes is either the _______ or the iliac crest.

Answer 23

sternum

Question 24

True or False: Erythropoietin is secreted by the liver.

Answer 24

False

Question 25

What is the average volume of a mature erythrocyte?

Answer 25

Approximately 60 fL

Question 26

What are the changes in cell size during normal erythropoiesis?

Answer 26

Cell size decreases

Question 27

What is Thymidine triphosphate (TTP)?

Answer 27

One of the four nucleoside triphosphates used in the in vivo synthesis of DNA

Question 28

What causes failure to absorb vitamin B12?

Answer 28

Failure of the gastrointestinal tract

Question 29

What is erythropoiesis?

Answer 29

The process of red blood cell formation

Question 30

What is the role of intrinsic factor?

Answer 30

Combines with vitamin B12 in food and makes B12 available for absorption by the gut

Question 31

What happens in pernicious anemia?

Answer 31

Atrophic gastric mucosa fails to produce intrinsic factor

Question 32

Which hormones increase erythropoiesis?

Answer 32

* Androgen/testosterone * Thyroxine * Growth hormone * Prolactin * ACTH * Adrenocortical steroids

Question 33

How do androgens affect EPO production?

Answer 33

Enhance EPO production, leading to greater RBC count in males compared to females

Question 34

What is the effect of thyroxine on erythropoiesis?

Answer 34

Promotes erythropoiesis; causes polycythemia in hyperthyroidism and anemia in hypothyroidism

Question 35

What is the effect of oestrogen on EPO secretion?

Answer 35

Decreases EPO secretion by decreasing globin synthesis and depressing erythropoietic response to hypoxia

Question 36

What is the average life span of red blood cells (RBC)?

Answer 36

Approximately 120 days

Question 37

Where are old RBCs destroyed in the body?

Answer 37

In the red pulp of the spleen and by macrophages in the liver and bone marrow

Question 38

What happens to hemoglobin when RBCs are destroyed?

Answer 38

It is phagocytized by macrophages

Question 39

What are the components of hemoglobin breakdown?

Answer 39

* Haem * Globin * Iron * Porphyrin

Question 40

What happens to iron after RBC destruction?

Answer 40

Carried by transferrin to bone marrow for erythropoiesis or stored in the liver as ferritin

Question 41

Fill in the blank: The destruction of RBCs results in the production of _______.

Answer 41

Bilirubin