Haematopoiesis & Blood Cells Flashcards

(40 cards)

1
Q

what is haematopoiesis?

A

production of mature blood cells from precursor stem cells

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2
Q

what are stem cells?

A

stable and quiescent cells of mesoderm origin that can self renew indefinitely and undergo differentiation and proliferation to produce a certain type of blood cell

*once a stem cell has started down a specific pathway, it cannot go back

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3
Q

what is the primary site of haematoiesis?

A

red bone marrow

  • when born, all bones have red marrow and are involved
  • as we age, amount of red marrow decreased and is replaced with yellow marrow
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4
Q

what is the main sites of haematoiesis in children vs adults?

A

children - long bones of limbs

adults - skull, ribs, sternum, pelvis, proximal ends of femur (axial skeleton)

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5
Q

what does the common myeloid precursor differentiate stem cells into?

A

B cells, T cells, NK cells

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6
Q

what does the common myeloid precursor differentiate stem cells into?

A

megakaryocyte / erytheroid precursor -> RBC and platelets

granulocyte / macrophage precursor -> macrophage, basophils, eosinophils, neutrophils

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7
Q

what is the main stimulant for erythropoiesis?

A

reduced oxygen carrying capacity in blood - stimulates EPO production and release from the kidneys

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8
Q

cell lineage - what is polychromatic normoblast?

A

when Hb begins to be produced

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9
Q

cell lineage - what is orthochromatic normoblast?

A

when nucleus shrinks and all haemoglobin is present

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10
Q

cell lineage - what is reticulocyte?

A

orthochromatic normoblast becomes reticulocytes when nucleus extruded

these are the final precursors before mature RBCs

reticulocytes pass into the blood stream and circulate before becoming mature RBCs

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11
Q

how does reticulocytes differ from mature RBCs?

A

reticulocytes are larger and contain RNA (makes them polychromatic)

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12
Q

what are the features of a mature RBC?

A
biconcave shape
no nucleus (no DNA or RNA)
no mitochondria (only glycolysis)
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13
Q

what is the lifespan of a mature RBC and how are they removed?

A

120 days

removed by liver and spleen

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14
Q

what is haemoglobin composed of?

A

4 globin chains and a haem group

haem group: prophyrin ring / Fe2+ (ferrous)

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15
Q

there are multiple types of globin chain, with different combinations being seen at different stages of life, what chain is the only constant?

A

α chain

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16
Q

what globin chain is present in foetal haemoglobin (HbF)?

A

α2 Υ2

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17
Q

what are the three different forms of adult haemoglobin?

A

HbA: α2 β2 (97%)

HbA2: α2 δ2 (2.5%)

HbF: α2 Υ2 (0.5%)

18
Q

what do RBCs rely on for energy?

19
Q

what is the role of the NADH produced in glycolysis of RBC?

A

required to maintain iron in Fe2+ state (ferrous) - needs to be in this state to bind oxygen

20
Q

what is the name of the tripeptide structure which helps protect RBCs from reactive oxygen species which causes oxidative damage to cellular enzymes and Hb?

A

glutathione

  • functions as part of enzyme called glutathione reductase
  • in order for glutathione to function as part of GR, it needs to be in its reduced form
  • this is achieved via the activity of NADPH dependent glutathione reductase
21
Q

what cell is a precursor to platelets?

A

megakaryocyte (large cell with large lobulated nucleus)

*platelets are essentially buds of the megakaryocyte cytoplasm

22
Q

what is the lifespan of platelets?

23
Q

what are the key features of neutrophils?

A

multi segmented nucleus (polymorph)

expresses myeloperoxidase (peroxidase enzyme)

24
Q

what is the name of the process in which neutrophils leave the blood stream?

A

marginisation

25
what are the functions of neutrophils?
phagocytosis | recruitment of other immune cells
26
what causes neutrophilia (due to reducing marginisation)?
acute inflammation / infection haemorrhage pregnancy drugs = steroids
27
what causes neutropenia?
aplastic anaemia pancytopenia drugs = clozapine, carbimazole
28
what are the key features of eosinophils?
red staining granules | bi lobed horse shoe shaped nucleus
29
what are the functions of eosinophils?
allergy and defence against parasitic infections
30
what conditions are eosinophils raised in?
churg strauss atophy parasitic infections hodgkins
31
what is the most infrequent granulocyte?
basophils
32
what are the key features of basophils?
dark-staining granules that obscure nucleus
33
what is the function of basophils?
thought to be circulating version of mast cells but function not completely known
34
in what conditions is there an increase in basophils?
CML | polycythemia rubra vera
35
what are the key features of monocytes?
produced from same cell lineage as granulocytes | have large cytoplasm and pale, irregular nucleus (kidney shaped)
36
what is the function of monocytes?
they circulate for a couple of days before entering tissues and becoming macrophages where they are involved in phagocytosis and antigen presentation
37
in which conditions are monocytes increased?
``` chronic bacterial infections SLE RA lymphoma leukaemia ```
38
what are the key features of lymphocytes?
small cells with a proportionally large nucleus, with only a small rim of cytoplasm
39
in what conditions are lymphocytes increased in?
infection malignancy hyposplenism
40
in what condition is atypical lymphocytes seen and what do these look like?
glandular fever increase in cytoplasm and wrapping around red cells