Hematopoiesis

Question 1

What is hematopoiesis?

Answer 1

Process of blood cell formation

Question 2

What is the classical marker of hematopoietic stem cells?

Answer 2

CD 34

Question 3

When does hematopoiesis start in embryonic development?

Answer 3

Around the nineteenth day of embryonic development

Question 4

What are the two related theories on the origin of hematopoietic progenitor cells?

Answer 4

Polyphyletic Theory, Monophyletic Theory

Question 5

Which theory is most widely accepted among experimental hematologists?

Answer 5

Monophyletic Theory

Question 6

What is the name of the pluripotential stem cell suggested by the Monophyletic Theory?

Answer 6

Pluripotential stem cell

Question 7

What are the three phases of hematopoiesis?

Answer 7

Mesoblastic/Megaloblastic, Hepatic stage, Intramedullary/Myeloid

Question 8

What is the chief site of hematopoiesis during the Mesoblastic phase?

Answer 8

Yolk sac

Question 9

What is the chief site of hematopoiesis during the Hepatic stage?

Answer 9

Fetal liver, with contributions from spleen, thymus, lymph nodes

Question 10

What is the chief site of hematopoiesis during the Intramedullary/Myeloid phase?

Answer 10

Bone marrow

Question 11

What is the first blood cell formed during the Mesoblastic phase?

Answer 11

Primitive erythroblast

Question 12

What hemoglobins are produced by Primitive Erythroblasts?

Answer 12

Gower-1, Gower-2, and Portland

Question 13

How does yolk sac hematopoiesis differ from fetal and adult hematopoiesis?

Answer 13

Yolk sac hematopoiesis occurs intravascularly (within developing blood vessels)

Question 14

What is the predominant hemoglobin during the Hepatic stage?

Answer 14

Hb F (Fetal hemoglobin)

Question 15

Which organ is the first to develop in the fetus?

Answer 15

Thymus

Question 16

What is the role of the thymus during the Hepatic stage?

Answer 16

Major site of T cell production

Question 17

Which organs produce B cells during the Hepatic stage?

Answer 17

Kidneys and spleen

Question 18

When does hematopoiesis start in the bone marrow?

Answer 18

Before the 5th month of fetal development

Question 19

When does bone marrow become the chief site of hematopoiesis?

Answer 19

By the end of 24 weeks’ gestation

Question 20

Where are hematopoietic tissues located in adults?

Answer 20

Bone marrow, lymph nodes, spleen, thymus, liver

Question 21

What is produced by the bone marrow in adults?

Answer 21

Developing erythroid, myeloid, lymphoid, and megakaryocytic cells

Question 22

What function does bone marrow have in adults?

Answer 22

Acts as a primary lymphoid organ

Question 23

How many RBCs are generated per kilogram of body weight daily by the bone marrow?

Answer 23

2.5 billion RBCs

Question 24

How many granulocytes are generated per kilogram of body weight daily by the bone marrow?

Answer 24

1 billion granulocytes

Question 25

How many platelets are generated per kilogram of body weight daily by the bone marrow?

Answer 25

2.5 billion platelets

Question 26

What is retrogression in the context of hematopoiesis?

Answer 26

The process of replacing red marrow with yellow marrow during development

Question 27

When does retrogression occur in humans?

Answer 27

Between 5 and 7 years of age

Question 28

What is the result of retrogression in adults? (RSVP)

Answer 28

Red marrow is restricted to the ribs, sternum, skull, shoulder blades, vertebrae, and proximal ends of long bones

Question 29

What is yellow marrow made of?

Answer 29

Adipocytes

Question 30

How does yellow marrow respond to increased demand on the bone marrow?

Answer 30

It can revert back to active marrow

Question 31

What are the proportions of red and yellow marrow in adults?

Answer 31

Approximately equal amounts, 50% red marrow and 50% yellow marrow

Question 32

What is the function of red marrow?

Answer 32

Hematopoietic activity, producing RBCs, WBCs, and platelets

Question 33

What is the function of yellow marrow?

Answer 33

Inactive hematopoietic activity, made up of adipocytes

Question 34

When does yellow marrow replace red marrow in childhood?

Answer 34

Between 5 to 7 years old

Question 35

Where does lymphoid development occur?

Answer 35

Primary lymphoid organs (bone marrow and thymus), secondary lymphoid organs (spleen and lymph nodes)

Question 36

What are primary lymphoid organs?

Answer 36

Bone marrow and thymus

Question 37

Function of primary lymphoid organs?

Answer 37

Derivation of T and B lymphocytes

Question 38

Location of B cell differentiation?

Answer 38

Bone marrow

Question 39

Thymus during fetal development?

Answer 39

Increases in size until puberty, then atrophies with aging

Question 40

Major secondary lymphoid organs?

Answer 40

Spleen and lymph nodes

Question 41

Functions of secondary lymphoid organs?

Answer 41

Trapping foreign substances, antibody production, T lymphocyte induction

Question 42

Largest secondary lymphoid organ?

Answer 42

Spleen

Question 43

Lymph node shape and size?

Answer 43

Small, ovoid, bean-shaped, < 1 cm in diameter

Question 44

Role of spleen in immunity?

Answer 44

Synthesis and release of antibodies

Question 45

What is lymphoma?

Answer 45

Solid tumor of lymphoid tissue

Question 46

Effects of splenectomy in children?

Answer 46

Increased bacterial sepsis (S. pneumoniae, N. meningitidis, H. influenzae)

Question 47

Effects of splenectomy in adults?

Answer 47

Increased blood-borne bacterial infections

Question 48

What is splenomegaly?

Answer 48

Enlargement of the spleen

Question 49

Minor secondary lymphoid organs?

Answer 49

Tonsils, appendix, Peyer's patches, MALT

Question 50

Function of Peyer's patches?

Answer 50

Detect substances in the small intestine lining

Question 51

What is MALT?

Answer 51

Unencapsulated lymphoid tissues in mucosal areas

Question 52

What is extramedullary hematopoiesis?

Answer 52

Hematopoiesis in the liver in response to infection or myelofibrosis

Question 53

Role of liver in hematopoiesis?

Answer 53

Maintains hematopoietic stem cells for blood cell generation