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Histology > Exam2Lec7Hematopoiesis&Bone Marrow&Thymus > Flashcards

Exam2Lec7Hematopoiesis&Bone Marrow&Thymus Flashcards

1
Q

Which organs are primary lymphoid organs (2)? What cells do they produce?

A
  • Thymus = T cells
  • Bone marrow = B cells
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2
Q

Which organs and tissue are secondary lymphoid organs and tissues (4)?

A
  • Diffuse lymphatic tissue (e.g. GALT)
  • Lymphatic nodules and tonsiles
  • Lymph nodes
  • Spleen
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3
Q

Where are T cells found?

A

Thymus

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4
Q

Where are B cells found?

A

Bone marrow and gut associated lymphatic tissues (GALT) in humans

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5
Q

After birth, where does hemopoiesis occur?

A

occurs only in red bone marrow and lymphatic tissues

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6
Q

Explain the 3 phases/stages of fetal hemopoiesis

A

1st phase: Embryonic yolk sac = formation of blood islands (RBCs only)
2nd phase: red and some WBCs
3rd phase: Bone marrow = RBCs and WBCs, also spleen and lymphatic organs

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7
Q

What are the two types of bone marrow? Which one is active and inactive? What do they produce?

A

*Red marrow = active, produce blood cells
* Yellow marrow = inactive, produce fat cells

red marrow changes gradually to yellow (inactive)

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8
Q

What makes up active(red) normal bone marrow in adults (3)?

A
  1. stroma (reticular cells) = produce reticular fibers network
  2. blood-forming cords (dividing hemopoietic cords)
  3. endothelial-lined sinusoids with discontinuous base membrane
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9
Q

Newborns have which type of bone marrow?

A

red

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10
Q

Where are lymphocytes formed?

A

formed in red bone marrow and in the lymphatic tissues

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11
Q

In adults, erythrocytes, granulocytes, monocytes, and platelets are formed where?

A

red bone marrow

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12
Q

**Explain steps of bone marrow aspiration(3) **

A
  1. needle inserted into hip bone (preferred anatomical site)
  2. small amount of bone marrow obtained
  3. aspirate is spread on a glass slide

inject needle into bone marrow and smear on slide

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13
Q

Explain steps of bone marrow core biopsy (3)

A
  1. intact bone marrow is obtained by a small incision in the skin
  2. biopsy needle is inserted into bone using a corkscrew movement to obtain a solid piece of bone marrow
  3. biopsy is used to diagnose and stage different types of cancer or monitor the results of chemotherapy

take an actual piece of bone marrow and screen for cancer

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14
Q

Which cells are the last cell capable of mitosis for platelets (endomitosis)?

A

Megakaryoblasts = chromosome replication

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15
Q

Under hormone stimulation by ____ causes a megakaryoblast to become a megakaryocyte (platelet-producing cell).

A

thrombopoietin

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16
Q

Where do platelets originate in adults?

A

red bone marrow by fragmentation of the cytoplasm of mature megakaryocytes

a multipotential myeloid stem cell precursor->megakaryoblasts->megakarocyte by stimulation of thromboietin-> platelet

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17
Q

What is the precursor for the red cell and white cell lineage?

A

multipotential myeloid stem cell

before that is a pluripotential hematopoietic stem cell

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18
Q

Breifly explain cell movement to sinusoid capillary and platelet formation

slide 21

A
  1. Mature megakaryocye pushes against a sinusoial endothelial cells
  2. They get fusied into the membrane is this causes a temporary opening b/w endothelial cells and then closes after cell completes production of platelets
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19
Q

List stages of erythrocyte lineage (erythropoiesis) (6)

A
  1. Proerythroblast
  2. Basophilic erythroblast
  3. Polychromatophilic erythroBLAST (last mitosis)
  4. Orthochromatophilic erythroblasts aka normoblast
  5. Polychromatiphilic (polychromatic) erythroCYTE -Reticulocyte
  6. Erythrocyte (mature cell)
    “Powerful Businesses Pollute Our Rural Environment”

All blasts are still mitotically active and can further differentiate

20
Q

RBCs develop from the multipotential ______ stem cell in bone marrow under the influence of ____ and some cytokines.

A
  • myeloid
  • erythropoietin

helps with development

21
Q

What are the major changes during the process of erythrocyte maturation (6)?

A
  • Cell volume decreases
  • Nucleoli diminish in size until they become invisible under LM
  • Nuclear diameter decreases
  • Chromatin becomes increasingly dense = thickened and reduced in size and finally extruded from the cell
  • Cytoplasmic basophilia (ribosomes) decrease while acidophilia (hemoglobin) simultaneously increases

gradual reduction in cell diameter and incr nuclear condensation of chromatin
bigger cell=younger
becmes lighter and smaller as it matures

22
Q

How many days does it take RBCs to develop?

A

7 days

23
Q

How manys to RBCs circulate in the blood?

A

120 days

24
Q

What occurs when a proerythroblast transitions to an erythrocyte (2)?

A
  1. increase in cytoplasmic hemoglobin concentration
  2. decrease in nuclear volume and an increase in chromatin condensation followed by extrusion of a pyknotic nucleus
25
Q

Explain the process of a reticulocyte becoming a mature erythrocyte

A
  1. Nuclues is extruded to become a an immature erythocyte (reticulocyte)
  2. Reticulocyte will leave the bone marrow, pass to bloodstream, lose its mitochondria and ribosomes within 1-2 days = becomes a mature erythrocyte

macrophages will then phagocytize discarded nucleu

26
Q

1-2% of total RBC count in peripheral blood, but may be elevated in blood to compensate for blood loss

A

Reticulocyte

27
Q

What are the possible pathological causes involving RBCs?

A
  • anemia
  • thalassemia
  • miliary tuberculosis
  • cancers involving bone marrow (myelomas, leukemias, lymphomas) and chronic hypoxemia
28
Q

What are the 6 stages of leukopoiesis?

A
  1. Myeoblast
  2. Promyelocyte = largest cell, primary azurophilic granules only produced in this stage
  3. Myelocyte = primary (azurophilic) granules + secondary (specific) granules produced (1st time secondary granules are produced)
  4. Metamylocyte (only in neutrophils and eosinophils) = nucleus is kidney shaped
  5. Band cell = only in neutrophils
  6. Neutrophilic granulocyte = 1st sign of the development of neutrophil, eosinophil, basophil

myelo-oval
meta-indented
mature-segemented

29
Q

Where are monocytes produced?

A

in bone marrow from a biopotential stem cell

monocyted and neutrophils are formed from the same stem cell

30
Q

Do monocytes have specific cytoplasmic granules?

A

NO, only azurophillic granules with lysosomal enzymes

31
Q

Monocytes travel to tissues where they become…?

A

macrophages

32
Q

Cell stages for monocyte formation

ly

A

myeloid stem cell->myeloblast-> promonocyte (monoblast)->monocyte

33
Q

Leukopoesis-Lymphocyte

Lymphocyte
produced where?
contains what type of granules?
what can it do?

A

produces in bone marrow (primary lymphoid organ)
Contain only primary azuro granules
only cells to be able to recirculate blood

34
Q

3 characteristics of lymphocytes

A
  1. thin (basophilic) cytoplasm
  2. large nucleus (takes up entire cell)
  3. T-cells (thymus), b cells (bone marrow)-immune fxn
35
Q

What is aplastic anemia also called?

A

hypocellular bone marrow

36
Q

What is aplastic anemia marked with pancytopenia?

A

reduction in the # of erythrocytes, all WBCs, and platelets in blood circulation

37
Q

What causes aplastic anemia (aka hypocellular bone marrow)?

A
  • Many cases are idopathic = unknown
  • Some can follow toxic exposure to chemotherapy drugs or to chemicals such as benzene, radiation, and infection with viral hepatitis
38
Q

How is aplastic anemia (aka hypocellular bone marrow) treated?

A
  • bone marrow transplantation
  • anti-lymphocyte globulin (in idopathic cases)
39
Q

What is the function of the thymus?

A
  • primary lymphatic organ
  • educates thymocytes (before becoming T-cells)
40
Q

What makes up the structure of the thymus?

A
  • capsule: poorly developed
  • **epithelioreticular cells (aka nurse cells) = responsible for development and maturation of T-cells **
  • few fibers
  • No lymphatic nodules = no interaction with B cells

lymphatic nodules are where T and B cells interacts, so w/o it, T cells are able to develop w/o B cells coming in the way

41
Q

What is the function of Hassall’s corpuscle (thymic corpuscle)?

A

produce interleukins that function in differentiation and education of T cells

site of final stage of T-cell education

hassal corpuscle=medullary epithoreticular cells=located in medulla

42
Q

Lymphatic vessels of the thymus are?

A

efferent

43
Q

What is the purpose of the blood thymus barrier?

A

To keep B cells from penetrating and interacting with T cells

microcirculation: postcapillary venules and thymus blood barrier to protect T cells

44
Q

How do mature T cells (CD8+ and CD4+) leave the cortex?

A

through postcapillary venules in medulla and enter the blood circulation

early stage T cells in the cortex migrate to medulla for education. Mature T-cells (in medulla) leave the thymus via post capillary venules-> Tcells enter blood circulation

45
Q

What is DiGeorge Syndrome?

A

an inherited immunodeficiency disease

46
Q

What causes DiGeorge Syndrome?

A
  • the cortical epithelial (epithelioreticular) cells did not develop = thymus is underdeveloped = no T cell education b/c lack of epithelioreticular cells
47
Q

What is the result of DiGeorge Syndrome?

A
  • lack of cell-mediated immunity (low T cell count)
  • loss of parathyroid gland and cardiac abnormalities

Histology (39 decks)

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