Hematopoiesis Phases and Sites Flashcards by Penny Nichols

What is the definition of hematology?

Simple: the study of blood cells
Expanded: the study of blood cell morphology, function, blood-forming organs, and diseases of the blood and bone marrow

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What are the formed elements of the blood?

Erythrocytes (RBCs)
Leukocytes (WBCs)
Thrombocytes (platelets)

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What is the layer between the RBCs and the plasma called in a tube with anticoagulant in it? What does that layer consist of?

the buffy coat

- made up of WBCs and platelets

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What two elements need to be present and activated for a clot to form in a specimen?

Fibrinogen and thrombin. Thrombin takes fibrinogen into fibrin, which is another name for the clot

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What does EDTA stand for? What are the types available?

ethylenediamine tetraacetic acid

- avaliable as a disodium or dipotassium salt (preferred for solubility)

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What concentration of EDTA is preferred?

What specifically does it do to prevent clot formation?

EDTA is used in a concentration of 1mg / 1ml of blood

- it chelates (removes) calcium, which prevents the formation of thrombin

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How long after draw is an EDTA tube good for blood smears? What happens after 2 hours that makes it unacceptable?

good for 2 hours after draw. Beyond that, cell morphology begins to change

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How long is an EDTA good for when refrigerated? What tests can be performed on this specimen?

Good for 24 hours for tests such as hemoglobin and cell counts

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What are some examples of artefacts?

crenated cells: cells with wavy edges
WBCs with odd-shaped nuclei: segmented neutrophil nuclei will split completely
platelet clumping
cells with unusual morphology

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What can cause artefacts?

Not mixing blood thoroughly after draw - results in clot formation

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What is the definition of hematopoiesis?

the process of blood cell production, differentiation, and development

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What 5 organs make up the hematopoietic system?

bone marrow
liver
spleen
lymph nodes
thymus

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What is the ratio of RBCs : Plasma : WBCs/platelets in a whole blood specimen?

44% : 55% : 1%

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Defining characteristics of:
A: segmented neutrophil
B: Band neutrophil
C: Eosinophil
D: Basophil
E: Lymphocyte
F: Monocyte

A: nucleus appears “pinched”
B: nucleus not “piched,” relatively same width
C: when stained, will have pink/orange granules from the eosin dye
D: have blue granules
E: Very large, dark nucleus, takes up majority of the cell
F: Cytoplasm has a very “lacy” appearance. Nucleus looks to be “stretched out”

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Hematopoietic stem cells are capable of _____? (2 things)

Self-renewing

- Differentiation

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What are the three phases of cell development?

Mesoblastic
Hepatic
Medullary (aka myeloid)

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Where is the primary site of mesoblastic cell development?

At what gestational age does cell development begin?

Primary site is the yolk sac

- Begins @ 19 days after fertilization

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What are the three types of hemoglobin produced by erythrocytes in the mesoblastic phase?

Gower-1
Gower-2
Portland

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When does the hepatic stage of cell development begin?

What organ is responsible for cell development in this stage?

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begins at 5-7 gestational weeks

- liver takes over from the yolk sac

What are the types of blood cells present in the hepatic phase of cell development?
What organs do they colonize?

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Lymphoid cells; Clusters of erythroblasts, granulocytes and monocytes
fetal liver, thymus, spleen, placenta, and ultimately the bone marrow space

What is extravascular hematopoiesis?
In what phase does EV hematopoiesis begin?
What gestational age?

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Extravascular: outside the blood vessels
Hepatic phase
Around the third month of fetal development

What is the first fully developed hematopoietic organ? What cells is it responsible for?

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Thymus

- T-cells

What organs are responsible for producing B-cells in the hepatic phase?

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Kidneys and spleen

What phase of cell development do we begin to see megakaryocytes present?

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hepatic phase

``` What is the predominant hemoglobin found in the hepatic phase? What type(s) of hemoglobin is it replacing? ```

- Hemoglobin F most predominant | - Replaces Gower-1, Gower-2, and Portland from mesoblastic phase

At what age of development does the medullary phase begin/become primary phase? Where is the primary site of hematopoiesis?

- Begins before the fifth month (end of 24th week) | - Cell development moves to the medullary area of the bone marrow

At what stage is the adult ratio of myeloid:erythroid activity seen? What is that ratio?

- Seen in the medullary stage | - Ratio is 3:1 M:E, which means that three times more lymphocytes are being produced than erythrocytes

What are the two types of hemoglobin present in the myeloid stage? What are the three types of cytokines found in this stage?

- Hbg: F (predominant) and A | - Cytokines: EPO, G-CSF, and GM-CSF

What cells are the thymus responsible for? What markers does it add to those cells?

- Adds CD 4 and CD 8 to T-cells

What organs are involved in adult hematopoietic tissue?

- Bone marrow - Liver - Spleen - Thymus

What are the primary and secondary lymphoid development tissues in adults? When do the secondary tissues help in development?

- Primary: Bone marrow and thymus (B & T cells) - Secondary: Spleen, lymph nodes, MALT - -not active unless other sites are rendered incapable

What are the two components of bone marrow and when are they active?

- Red marrow: primary site of cell development, and most of the time, maturation - Yellow marrow, contains adipocytes, undifferentiated mesenchymal cells and macrophages. Not a site for cell production, but can become red marrow when the original marrow is unable to produce cells

What is bone marrow retrogression? At what age do we start seeing this occur? What is the ratio of red:yellow in adults?

- The process of red marrow becoming yellow marrow - Begins at around 5-7 years old. Before this age, all marrow is active red marrow. - By adulthood, ratio is 50:50

Where in the bone marrow do: erythrocytes develop?megakaryocytes develop? (Im)mature myeloid cells develop?

- Erythrocytes: clusters on the outer surfaces of the vascular sinuses - Mega: adjacent to the walls of the vascular sinuses - facilitates release of platelets into the lumen - Immature: through to the metamyelocyte stage located deep in the cords - Mature: moved closer to the vascular sinuses

What are Kupffer cells?

- macrophages that remove senescent (aged) cells and foreign debris from the blood that circulates through the liver

What organ removes membrane-damaged RBCs from circulation?

- The liver

What is extramedullary hematopoiesis? | What organ is responsible for maintaining it?

- hematopoiesis occurring outside of the bone marrow | - The liver

What are enzymatic storage diseases (3) that effect Kupffer cells and result in hepatomegaly?

- Gaucher disease - Niemann-Pick disease - Tay-Sachs disease

What is the largest lymphoid organ in the body and what are the three types of tissues that make up this organ?

- The spleen - White pulp (lymphocytes, macrophages, and dendritics) - Red pulp (specialized macrophages) - Marginal zone

Where are the cords of Billroth located?

- The red pulp of the spleen

What is the cellular distribution of the spleen (4 types)? | What are the cells responsible for?

- B lymphocytes - Macrophages - - RBC removal - Culling cells - - Phagocytized with subsequent degradation of cell organelles - Pitting splenic macrophages - - Remove inclusions or damaged surface membrane from the circulating RBCs

What are some common causes of splenomegaly? | Seven examples given

- Leukemias - RBC enzyme defects - Hemoglobinopathies - Hodgkins lymphoma - Thalassemias - EBV/mono - Malaria

What type of cells are stored in the spleen? | About how much of the body's supply is stored there?

- About 30% of the body's platelets are stored in the spleen

What is an autosplenectomy? | For what blood disorder is this a common symptom?

- When the body attacks/damages its own spleen | - Common symptom of sickle cell anemia

What are the three major functions of the lymph nodes?

- Site of lymphocyte proliferation - Initiation of the specific immune response to foreign antigens - Filter particulate matter, debris, and bacteria entering the lymph node via the lymph

Where is the thymus located? | What is the cell distribution (6 types)?

- Upper part of the anterior mediastinum at about the level of the great vessels of the heart - Cellular distribution lymphoid cells, mesenchymal cells, reticular cells, epithelial cells, dendritic cells, and many macrophages

What happens to the thymus as we age? | At what ages do these changes typically occur?

- Weighs 12 to 15 g at birth - Increases to 30 to 40 g at puberty - Decreases to 10 to 15 g at later ages

Hematopoiesis Phases and Sites Flashcards

(47 cards)