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Hematology and Oncology > EXAM #1: HEMATOPOESIS > Flashcards

EXAM #1: HEMATOPOESIS Flashcards

1
Q

What is the definition of hematopoiesis?

A

Formation of blood cells

Note that hematopoiesis provides the cellular elements of the peripheral blood i.e. leukocytes and RBCs.

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2
Q

Where does hematopoiesis occur?

A

Bone marrow

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3
Q

What is the lifespan of a lymphocyte?

A

Years

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4
Q

What is the lifespan of a RBC?

A

120 days

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5
Q

What is the lifespan of a platelet?

A

7-10 days

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6
Q

What is the lifespan of a granulocyte?

A

6-8 hours

Given the lifespan of granulocytes vs. RBCs; there are MORE granulocyte precursors in the bone marrow*

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7
Q

What cells are collectively called “granulocytes?”

A
  • Eosinophils
  • Mature segmented neurtorpils
  • Basophils
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8
Q

What are hematopoietic stem cells?

A

Cells that give rise to progenitor cells of ALL lineages

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9
Q

List the characteristics of hematopoietic stem cells.

A

1) High proliferative potential
2) Capable of self-renewal and differentiation
3) Multipotential

Note that these cells CANNOT be identified morphologically.

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10
Q

What are bone marrow stromal cells?

A

Cells in the bone marrow that allow hematopoietic stem cells to develop

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11
Q

Describe the interactions between bone marrow stromal cells and hematopoietic stem cells.

A

These cell types bind together

  • Tight binding the more immature the stem cell
  • Looser binding the more differentiated
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12
Q

What is the role of cytokines in the bone marrow/ hematopoiesis?

A

Cytokines drive specific cell differentiation pathways

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13
Q

What is the difference between a progenitor cell cytokine and an end-stage cytokine?

A

Progenitor= act on immature cells

End-stage= act on more differentiated cell types

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14
Q

What is the role of G-CSF in hematopoiesis?

A

“Granulocyte Colony Simulating Factor”

  • Released by macrophages at inflammatory sites
  • Circulates to bone marrow
  • Causes the production and release of NEUTROPHILS, basophils, and eosinophils
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15
Q

What is the role of EPO in hematopoiesis? What organ produces EPO? Why?

A

ERYTHROPOIETIN

  • Production and release of RBCs in response to HYPOXIA
  • Released by peritubular interstitial cells in the kidneys
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16
Q

What is the role of TGF-B in hematopoiesis?

A

Transforming Growth Factor- Beta

  • DOWNREGULATION of cells in the bone marrow
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17
Q

What is the clinical utility of G-CSF?

A

1) Given to donors to release bone marrow stem cells into the peripheral blood
2) Stimulation of granulopoiesis following chemotherapy-induced marrow suppression.

Note that flow cytometry can be used to isolate bone marrow stem cells, to isolate them and give them to patients. Second, chemotherapy will commonly have a negative impact of granulocytes in the bone marrow. G-CSF will stimulate the production of these granulocytes to allow for more frequent chemotherapy, and decreased infection in the chemotherapy induced immunosuppressed state.

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18
Q

What is GM-CSF? What is the clinical utility of GM-CSF?

A

Granulocyte-Macrophage Colony Stimulating Factor

This is given to increase myeloid cell recovery in bone marrow transplant patients

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19
Q

What are the two different forms of bone marrow? Generally, what is the difference between the two?

A 
Yellow= inactive 
Red= active
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20
Q

What type of marrow is present in the first few years of life?

A

Red

21
Q

Where is red marrow located after age 18?

A

1) Ribs
2) Sternum
3) Pelvis

22
Q

What is extramedullary hematopoiesis? Where can this take place?

A

This is hematopoiesis that occurs OUTSIDE of the bone marrow. It takes place in the:

1) Spleen
2) Liver

23
Q

Generally, what happens to RBCs during erythropoiesis?

A

As the cell matures:

1) Cell size decreases
2) N:C ratio decreases
3) Nucleoli decrease in # and disappear
4) Cytoplasmic staining goes from darker blue to lighter blue

24
Q

What is the definition of erythropoiesis?

A

Formation or production of RBCs

25
Q

Where does erythropoiesis initially occur?

A

Embryonic yolk sac

26
Q

Where does erythropoiesis continue after birth?

A

Liver and spleen, and then eventually transitions to bone marrow

27
Q

What is a reticulocyte?

A

Immature RBC that is one step removed from mature

28
Q

What is the normal percentage of reticulocytes?

A

1%

29
Q

What is an elevated reticulocyte count an indication of?

A
  • Bone marrow stress

- Increased need for new RBCs

30
Q

What is the definition of granulopoiesis?

A

Production of granulocytes:

  • Neutrophils
  • Eosinophils
  • Basophils
31
Q

What is a band? What is a normal band count?

A

1 Step removed from a mature neutrophil

3-5%

32
Q

What is an elevated band count an indication of?

A

Infection: the body is “kicking out” bands that will mature on the way to the site of infection

Specifically, bands are associated with BACTERIAL infection

33
Q

What is the clinical nomenclature for an increased band count?

A

“Left shift”

This just refers to a shift the the left in the cell lineage.

34
Q

What are the two pools of neutrophils?

A

Marginating= loosely attached

Circulating= circulating in the blood

Note that there is roughly a 50/50 ratio of these.

35
Q

What organ/ cell is responsible for the removal of dead granulocytes?

A

Splenic phagocytes

36
Q

What cell do macrophages develop from?

A

Monocytes

37
Q

When does a monocyte become a macrophage?

A

Once it has migrated from the blood into the tissue

38
Q

What is lymphopoiesis?

A

Production of lymphocytes:

  • T-cells
  • B-cells
  • NK-cells
39
Q

Where do B-cells mature?

A

Bone marrow

40
Q

When do you get rid of self-reactive B-cells? What immunoglobulin/s is/are expressed at this time?

A
  • Immature B-cell stage

- IgM

41
Q

What is a mature B-cell?

A

B-cell expression IgM and IgD

42
Q

Where do T-cells mature?

A

Thymus

Note that nearly 95% or prothymocytes that have come from the bone marrow to to the thymus, die in the thymus.

43
Q

What is thrombopoiesis?

A

Production of platelets i.e. “thrombocytes”

44
Q

What are the functions of platelets?

A
  • Limit bleeding

- Repair endothelium

45
Q

What are platelets i.e. what cell are platelets derived from?

A
  • Anuclear cytoplasmic remnants of megakaryocytes

- Specifically, platelets come from long cytoplasmic extensions of megakaryocytes

46
Q

What is the process that megakaryocytes undergo to produce platelets?

A

Endomitosis

47
Q

What stimulates thrombopoiesis?

A

Thrombopoietin

48
Q

What is the difference between an “absolute cell count” and a “differential count”

A

Absolute= quantity of each cell type

Differential= % of each cell type i.e. a relative count

Note that you must look at BOTH of these to determine NORMAL count.*

Hematology and Oncology (38 decks)

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