Hematopoiesis

Question 1

In what week of gestation does fetal hematopoiesis begin?

Answer 1

Week 3

Question 2

What is the sequence of embryonic organs that take over hematopoiesis?

Answer 2

Young (1) Liver (2) Synthesizes (3) The (4) Blood

(1) Liver
(2) Spleen
(3) Thymus
(4) Bone marrow

Question 3

What are the five white blood cell types, in order of prevalence?

Answer 3

Never Let Monkeys Eat Bananas

(1) Neutrophils
(2) Lymphocytes
(3) Monocytes
(4) Eosinophils
(5) Basophils

Question 4

When does medullary hematopoiesis (in bone marrow) begin in the fetus?

Answer 4

5 months of gestation

Question 5

What is a characteristic feature of stem cell division in hematopoiesis?

Answer 5

Asymmetry - one cell retains properties of the stem cell

Question 6

What are two causes of induced hematopoiesis?

Answer 6

(1) Infection leads to increased production of neutrophils

(2) Anemia leads to increased production of RBCs

Question 7

What do stromal cells in bone marrow do?

Answer 7

(1) Nurture and protect stem cells, (2) secrete factors that are chemotactic for hematopoietic cells

Question 8

Where are bone marrow aspirations drawn from in children?

Answer 8

Anterior tibia

Question 9

What is the term for replacement of cellular bone marrow with fat? At what age does this occur?

Answer 9

Involution at 5-7 years

Question 10

After ~20 years, where is cellular marrow found?

Answer 10

(1) Sternum
(2) Ribs
(3) Pelvis
(4) Vertebrae
(5) Skull
(6) Scapulae
(7) Proximal ends of long bones

Question 11

How long does it take reticulocytes to mature to RBCs?

Answer 11

About 3 days (2 in bone marrow + 1 in peripheral blood)

Question 12

What is a marker for hematopoietic stem cells?

Answer 12

CD34

Question 13

Where are neutrophils found?

Answer 13

(1) 50% in marginal neutrophil pool and (2) 50% in circulating neutrophil pool

Question 14

What do steroids do to neutrophil populations?

Answer 14

Movement from marginal neutrophil pool to the circulating neutrophil pool

Question 15

How long do neutrophils circulate?

Answer 15

10-14 hours

Question 16

What is the life span of RBCs and platelets?

Answer 16

RBCs: 120 days
Platelets: 7-10 days

Question 17

When are hypersegmented neutrophils found?

Answer 17

Folate and vitamin B12 deficiency

Question 18

What are G-CSF and GM-CSF and what do they do?

Answer 18

Granulocyte colony stimulating factor and granulocyte-macrophage colony stimulating factor - stimulate differentiation and mobilization of stem cells into peripheral blood

Question 19

What stimulates the differentiation and maturation of megakaryoblasts and megakaryocytes?

Answer 19

Thrombopoietin (TPO)

Question 20

Where are bone marrow aspirations drawn from in adults?

Answer 20

Posterior superior iliac crest

Question 21

What is the term for variation in RBC diameter on blood film?

Answer 21

Anisocytosis

Question 22

What are the staining characteristics in Wright stain?

Answer 22

(1) Methylene blue stains acidic structures blue (basophils)
(2) Eosin stains basic structures pink (eosinophils)
(3) Neutrophils are purple from being stained by both methylene blue and eosin

Question 23

What is a band shift or left shift?

Answer 23

(1) Increase in bands and immature neutrophils in peripheral blood (2) due to proliferation of myeloid cells

Question 24

What is a consequence of hematopoiesis occurring throughout the skeleton in children?

Answer 24

Hyperactive immunity