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Fundamentals of Pathology > Origin of Blood Cells > Flashcards

Origin of Blood Cells Flashcards

1
Q

define haematopoiesis

A
  • the production of erythrocytes, leukocytes and platelets from haematopoeitic stem cells (HSCs)
  • highly regulated to maintain circulating cell numbers within a relatively constant level
  • requires high levels of cell replication
  • maintiains balance between self-renewal, terminal differentiation, migration and cell death
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2
Q

where is the site of haemotopoiesis?

A

In early embryo

  • 1st trimester: yolk sac
  • 2nd trimester: liver and spleen
  • 3rd trimester: central and peripheral skeleton

After birth

  • infant: bone marrow
  • adulthood: axial skeleton, vertebral bones, sternum, ribs, pelvic, flat bone
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3
Q

what is extramedullary haemopoiesis?

A
  • haemopoiesis that occurs outside the bone marrow

- occurs in ties of severe demand and can expand to foetal sites

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4
Q

what is the importance of bone marrow?

A
  • site of haemopoiesis and is the spongy jelly-like tissue inside the bone
  • has many blood cells to bring nutrients and take away new blood cells
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5
Q

what are the 2 types of BM?

A
  • red marrow- has active haemopoiesis

- yellow marrow- contains fat cells

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6
Q

what is the purpose of BM biopsy?

A

used to examine BM architecture

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7
Q

what are the stages of haematopoeisis?

A

stem cells → progenitor cells → precursor cells → effector cells

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8
Q

describe pluripotent stem cells

A
  • unlimited self renewal and differentiation (except into placental cells)
  • present in BM in small numbers
  • very resistant to chemotherapy
  • resides in BM and small amount in circulation
  • has CD34+ surface antigen present
  • looks like small lymphocytes
  • dysfunction causes aplastic anaemia or certain leukaemia
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9
Q

describe multipoint stem cells

A
  • they are lymphoid and myeloid cells
  • derived from pluripotent cells
  • capable fo extended self renewal and differentiation
  • lymphoid cells differentiate into lymphocytes and can give rise to lymphoproliferative malignancies
  • myeloid cells differentiate int RBCd, granulocytes and platelets and can give rise to myeloproliferative leukaemia
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10
Q

what are a type of progenitor cell and describe them

A
  • colony forming unit (CFU)
  • derived from multipoint GCs
  • capable of limited self renewal and differentiation
  • responsive to haematopoietic growth factors, EG: EPO stems CFU-E
  • expresses differentiation surface antigens
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11
Q

give examples of what progenitor cells can differentiate into

A
  • CFU-GEMM
  • CFU-ME
  • CFU-GM
  • CFU-E
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12
Q

can progenitor cells and stem cells be recognised morphemically?

A

no, but progenitors can be seen in special in vitro assays where colonies form into specific shapes

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13
Q

what are precursor cells?

A
  • blasts and their progeny
  • the first morphologically identifiable cells
  • little if any renewal
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14
Q

give examples of precursor cells

A
  • eryhtroblasts
  • myeloblasts
  • monoblasts
  • lymphoblasts
  • megakaryoblasts
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15
Q

give examples of mature effector cells

A

RBCs, neutrophils, monocytes, lymphocytes, platelets

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16
Q

state the steps in granulopoiesis

A

1) multipotent SC w CD34+ antigen
2) myeloid SC
3) progenitor; CFU-GM
4) progenitor; CFU-G
5) precursor; myeloblast
6) precursor; promyelocyte
7) precursor; myélocyte
8) precursor; metamyelocyte
9) precursor- band
10) neutrophil

17
Q

what are the different types of granules that form in neutrophils as they mature?

A
  • primary azurophilic granules develop asneutrophils differentiate from myéloblastes to promyelocytes
  • secondary specific granules form in myélocytes and metamyelocytes
  • tertiary gelatinise granules first appear in band cells

secretory vesicles only present in mature neutrophils

18
Q

state the steps in erythropoiesis

A

1) multipotent SC w CD34+ antigen
2) myeloid SC
3) progenitor; BFU-ME
4) progenitor; CFU-ME
5) precursor; pro erythroblast
6) precursor; basophilic erythroblast
7) precursor; polychromatophilic
8) precursor; orthochromatic
9) precursor- reticulocyte
10) erythrocyte

19
Q

what are the stages in platelet formation?

A

haemocytoblast → megakaryoblast → promegakaryocyte → megakaryocyte → platelet

20
Q

what are the stages of lymphopoiesis?

A

1) antigen independent phase- initially in the BM, then matures in lymph nodes and thymus
2) 2nd cycle of differentiation and proliferation in response to antigen exposure
3) follows antigen exposure and lymphocyte may live for many years

21
Q

describe T cell formation in the thymus

A
  • early progenitor migrates to thymus
  • T cell receptor gene arrangement
  • +ve and -ve selection
22
Q

describe B cell formation in the BM

A
  • Ig gene arrangement
  • expression of surface IgM
  • immature B cells migrate to secondary lymphoid organs for maturation and antigen selection
23
Q

what is the function of haematopoietic growth factors and what are some examples?

A
  • cell to cell communication by binding via cell surface transmembrane receptors to secreted cytokines or GFs
  • stims growth and survival of progenitors
  • binding triggered signal transductionfollowed by gene transcription, proliferation, differentiation, apoptosis
  • some are specific
  • polypeptide growth factors: cytokines
  • erythopoietin: stimulates RBC production
  • granulocyte colony stimulating factor G-CSF
24
Q

where is erythropoietin produced and what is its function?

A
  • produced in the kidney in response to hypoxia
  • increases RBC production by increasing CFU-E
  • specific to erythroid lineage
  • acts on late progenitors

-used to treat anaemia of kidney failure and alternative to blood transfusion for Jehovah’s witnesses

25
Q

where is granulocyte colony stimulating factor (G-CSF) produced and what is its function?

A
  • produced by many cell types
  • in response to inflammation
  • acts on neutrophils in the periphery
  • stims neutrophil production in BM by stimulating CFU-G and progenitors of other lineages
  • used to treat neutropenia and other causes
  • stims neutrophil recovery after chemo and BM transplant
  • cause SC to be released from BM to circulation
26
Q

are haematopoietic stem cells the only type of SCs that cab give long term engraftment?

A

Yes, progenitors or precursors cannot

27
Q

when are BM transplants used?

A
  • in leukemia, lymphoma, myeloma
  • in intensified chemo for solid tumours
  • for genetic disorders like SCID and thalassemia

Fundamentals of Pathology (7 decks)

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