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Yr 1 PoM > Red cells > Flashcards

Red cells Flashcards

1
Q

where do all blood cells originate from

A

bone marrow derived from a cell → multipotent haemopoietic stem cell (HSCs)

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2
Q

recall which cells are then derived from multipotent haemopoetic stem cells

A
  • lymphoid stem cells

- myeloid stem cells (→ RBCs, platelets, granulocytes + monocytes)

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3
Q

define “haemopoisis”

A
  • production of blood cells

- occurs in the bone marrow

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4
Q

haemopoisis of erythrocytes

A

multipotent lymphoid-myeloid stem cell (HSC) → myeloid stem cell → erythrocyte
-same with granulocytes, monocytes -> macrophages, megakaryocyte

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5
Q

haemopoisis of B cells, T cells + NK cells

A

multipotent lymphoid-myeloid stem cell (HSC) → lymphoid stem cell → B, T, NK cells

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6
Q

two characteristics of HSCs

A

1) they can self renew (HSCs not depleted)

2) differentiate to mature progeny (not undifferentiated but can differentiate further?)

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7
Q

define “erythropoiesis”

A

development of erythrocytes

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8
Q

stages of erythropoiesis

A

myeloid stem cell → precursor cell (erythroblasts) → erythrocytes
-gradually loses its ribosome so loses its blue colour (Stain)

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9
Q

which growth factor is needed for erythropoiesis?

A
  • erythropoietin (GP synthesised in the kidney)

- stimulated by hypoxia/anaemia → stimulates BM to produce more RBCs (haemostasis)

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10
Q

where is erythropoietin synthesised?

A

1) 90% in juxatubular interstitial cell (kidney)

2) 10% hepatocytes + interstitial cells

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11
Q

how do RBCs structure help it transport oxygen?

A
  • haemoglobin → 2-alpha + 2-beta chains
  • each chain has a haem group held in a chain porphyrin → Fe2+ can bind to 1 O2
  • 300 million Hb in each RBC
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12
Q

why is it important to have these two different chains

A

-interactions between the globing chains for the delivery of O2 to the tissues

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13
Q

what type of haemoglobin in feotuses?

A

fetal haemoglobin - 2alpha + 2 gamma chains

-facilitates transfer of O2 between mother and foetus

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14
Q

where is iron absorbed?

A

duodenum

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15
Q

what is non-haem iron?

A

Fe3+ needs action of reduction substances form absorption ie. vit C

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16
Q

why is iron homeostasis important?

A

1) excessive iron taxi to liver + heart

2) no mech to excrete iron must be kept 1-2 mg per day

17
Q

which mechanisms reduce iron levels?

A

1) bone marrow → RBC recycled
2) liver storage
3) enzymes + myoglobin production

18
Q

proteins that block release of iron for the stores?

A

hepcidin

19
Q

how does hepcidin work?

A

1) released from liver (hep)

2) targets duodenum + macrophages (ferroportin degraded as hepcidin binds)

20
Q

which two vitamins are key to produce DNA?

A

1) vitamin B12

2) folate (folic acid)

21
Q

what does a deficiency of vitamins B12 and folate affect?

A

affects all rapidly dividing cells i.e. bone marrow, epithelial surfaces, gonads

-too large cells (can’t divide as not enough DNA + anaemia)

22
Q

how is vitamin B12 absorbed?

A

1) combines with intrinsic factor (IF) in stomach

2) B12-IF binds to ileum receptors

23
Q

reasons for B12 deficiency?

A
  • intake
  • IF recreation ie autoimmune disease
  • malabsoption
24
Q

how are RBCs destroyed?

A
  • in reticuloendothelial system
  • storage form of iron in macrophages
  • transferrin transports Fe in the plasma
25
Q

term to describe a SMALLER than normal rbc

A

microcyte (microcytic)

e.g. polychromatic microcyte (young RBC still synthesising heamoglobin)

26
Q

term to describe a LARGER than normal rbc

A

macrocyte

27
Q

three types of macrocytes

A
  • ovbal
  • round
  • polychromatic
28
Q

term to describe rbcs with a larger area of central pallor

A

hypochromic (ie. low Hb levels)

-goes with microcytosis often

29
Q

term to describe rbcs with a blue tint when stained

A

polychromasia (ie. higher Hb levels such as young rbcs)

-goes with macrocytosis often

30
Q

what stain colour are reticulocytes?

A
  • blue as higher RNA content so stains with methylene blue

- immature rbc

31
Q

term to describe variation in rbc size

A

anisocytosis

32
Q

term to describe variation in rbc shape

A

poikilocytosis

33
Q

examples of poikilocytes?

A

sickle cell, target cells

34
Q

how do target cells arise?

A
  • accumulation of Hb in the central area

- due to ie liver disease, spleen removal, jaundice

35
Q

what is the difference between symptoms and signs?

A
  • symptoms → what patient is feeling
  • signs → physical finding

-rbc morphology must been interpreted in relation to a patients symptoms + full blood count

36
Q

what factors affect ‘normal’?

A

-age, gender, ethnicity, altitude…

37
Q

how is a reference range determined?

A

derived from a reference population

  • sample using same techniques
  • ie free of infection, not access alcohol, age range
38
Q

what to look out for on a blood film?

A

-anaemia?/ blood count?
-clinical history?
blood film:
-size, shape, age(polychromasia)

Yr 1 PoM (17 decks)

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