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Haematology > Structure and Function of Blood > Flashcards

Structure and Function of Blood Flashcards

1
Q

What are the different types of blood cells?

A

RBC
WBC
Platelets

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2
Q

What is haematopoiesis?

A

Production of blood cells

Derived from a relatively small pool of pluripotent stem cells capable of making all the different types of blood cells

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3
Q

Where is the site of haematopoiesis in the embryo?

A

Yolk sac then liver then marrow

3rd to 7th month

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4
Q

Where is the site of haematopoiesis at birth?

A

Mostly bone marrow, liver and spleen when needed

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5
Q

Where is the site of haematopoiesis from birth to maturity?

A

Number of active sites in bone marrow decreases but retains the ability for haematopoiesis

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6
Q

Where is the site of hematopoiesis in adults?

A

Not all bones contain bone marrow

Haematopoiesis restricted to the skull, ribs, sternum, pelvis, proximal ends of femur

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7
Q

What has to happen to a stem cell to make blood?

A

Proliferation
Differentiation
Self renewal
Most stem cells are in a quiecent state

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8
Q

How will a neutrophil progress?

A

Myeloblast to promyelocyte to myelocyte through to metamyelocyte forms eventually to band forms and neutrophils that are seen in blood

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9
Q

Do cells get bigger or smaller as they divide?

A

Smaller

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10
Q

Describe the maturation progression of erythrocytes?

A 
Pronormoblast 
Basophilic 
Polychromatophilic
Orthochromatic 
Reticulocyte
Mature red cell
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11
Q

What is the precursor to platelets?

A

Megakaryocyte

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12
Q

What are the different forms of granulocytes?

A

Eosinophils
Basophils
Neutrophils

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13
Q

What is the structure of neutrophils?

A

Lobulated polymorphic nucleus

Neutral staining granules

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14
Q

What is the function of neutrophils?

A

Short life in circulation - transit to tissues
Phagocytose invaders
Kill with granule contents and die in the process
Attract other cells
Increased body stress - infection, trauma, infarction

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15
Q

What is the structure of eosinophils?

A

Bi-lobed

Bright orange/ red granules

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16
Q

What is the function of eosinophils?

A

Fight parasitic infection
Hypersensitivity; allergic reactions
Elevated in patients with allergic conditions; asthma, atopic rhinitis

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17
Q

What is the structure of basophils?

A

Infrequent in circulation

Large deep purple granules obscuring nucleus

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18
Q

What is the function of basophils?

A

Circulating version of tissue mast cells
Mediated hypersensitivity reactions
Fc receptors bind IgE
Granules contain histamine

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19
Q

What is the structure of monocytes?

A

Large single nucleus

Faintly staining granules, often vacuolated

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20
Q

What is the function of monocytes?

A

Circulate for a week and enter tissues to become macrophages
Phagocyte invaders; kill them and present antigen to lymphocytes
Attract other cells
More long lived than neutrophils

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21
Q

What is the structure of lymphocytes?

A 
Mature; small with condensed nucleus and a rim of cytoplasm 
If activated (atypical) - large with plentiful blue cytoplasm extending round neighbouring red cells
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22
Q

What is the function of lymphocytes?

A

Numerous types; B, T, NK

Cognate response to infection

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23
Q

What is the precursor cell to basophils, eosinophils, neutrophils and monocytes?

A

Myeloblast of which that is a lineage of common myeloid progenitor

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24
Q

What is the precursor cell to dendritic cells and macrophages?

A

Monocytes of myeloblast of common myeloid precursor

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25
Q

What is the precursor cell to platelets?

A

Megakaryocytes of myeloid progenitor

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26
Q

What is the immediate precursor cell to erythrocyte?

A

Reticulocyte

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27
Q

What is the precursor cell to B, T and NK cells?

A

Common Lymphoid progenitor

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28
Q

What cells will originate from common myeloid progenitor cells?

A

Megakaryocyte
Erythrocyte
Mast cell
Myeloblast

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29
Q

How are primitive precursor cells recognized?

A

Immunophenotyping; expression of antigens on cell surface

Bio-assays; culture in vitro and show lineage of progeny in different growth conditions

30
Q

Where are common sites for bone marrow aspiration?

A

Posterior iliac crests

31
Q

What is the name of a normal marrow biopsy?

A

Trephine

32
Q

What are the required properties of RBC?

A 
Full of Hb to carry oxygen 
No nucleus to allow flexibility and Hb molecules
No mitochondria
High surface area/ volume ratio 
Flexible to squeeze through capillaries
33
Q

What are the consequences of red blood structure?

A

Full of Hb; high oncotic pressure, oxygen rich environment (oxidation risk)
No nucleus; can’t divide or replace damaged proteins, limited life span
No mitochondria; limited to glycolysis
High SA/ volume ratio; need mechanism to keep water out
Flexible; specialised membrane required that can ensue mutations

34
Q

What molecules in the RBC membrane allow for flexibility?

A

Alpha and beta spectrin connected by tropomyosin actin complex

35
Q

What mechanism is present in RBC to ensure water is kept out?

A

Na/K+ ATPase pump (sodium out, potassium in)

36
Q

What type of protein is Hb?

A

Tetrameric globular protein

37
Q

What is the structure of Hb?

A

2 alpha and 2 beta chains
Heme group is Fe2+ in a flat porphyrin ring
One haem per subgroup
One oxygen binds to one Fe2+ (will NOT bind to oxidised Fe3+)

38
Q

What is the function of haemaglobin?

A

Delivers oxygen to tissues
Buffer for H+
CO2 transport

39
Q

What regulates red cell production?

A

Erythropoietin via hypoxia sensors in kidney

40
Q

What is the lifespan of a red blood cell?

A

120 days

41
Q

What happens to a red blood cells once it has reached its life span

A

Taken up by macrophages
Globin chains recycled to amino acids
Haem group broken down to iron and bilirubin
Bilirubin taken to liver to be conjugated and excretes in bile

42
Q

How is iron stored?

A

As ferritin or hemosiderin

Can be released to transferrin with the aid of ceruloplasmin

43
Q

What is the basic breakdown of haem?

A

Haem
Porphyrin
Biliverdin
Bilirubin

44
Q

What is the pathway of ATP production in red blood cells?

EXAM CONTENT

A

Embden-Meyerhof Pathway
Net gain of ATP and NADH
2 pyruvate

45
Q

What is the function of NADH in RBC?

A

Prevent oxidation of Fe2+ to Fe3+

46
Q

What is Fe3+ called?

A

Met Hb; oxidised Hb that has no capacity to carry O2

47
Q

What are the reactive oxygen species that can be found in RBC?

A

Superoxide
Hydrogen Peroxide
Free radicals that have an unpaired free electron and can interact with other molecules (protein, DNA) and damage their structure

48
Q

What enzyme converts superoxide to hydrogen peroxidase?

A

Superoxide dismutase

49
Q

What enzyme converts hydrogen peroxidase to water?

A

Peroxidases catalase

50
Q

What is the function of glutathione (GSH)?

A

Protects us from hydrogen peroxide by reacting with it to form water and oxidised glutathione product (GSSG)

51
Q

How can glutathione be replenished?

A

NADPH

52
Q

How is NADPH generated?

EXAM content

A

Hexose Monophosphate Shunt

53
Q

What is the rate limiting enzyme in the hexose monophosphate shunt that forms NADPH?

A

G6PD

54
Q

Can you have mutations in G6PD?

A

Yes; x-linked condition

55
Q

Why is a G6PD deficiency harmful?

A

Prevents neutralisation of damaging oxidative stress (hydrogen peroxide) to RBC
RBC will not live as long and will be hemolyzed

56
Q

How does CO2 get from the tissues to the lungs?

A

10% dissolved in solution
30% bound to Hb as carbamino-Hb
60% converted to bicarb

57
Q

What converts carbon dioxide to bicarb?

A

Carbonic anhydrase

58
Q

What exchange exports HCO3- from RBC?

A

Chloride/ bicarb shift

Cl- enters cell to preserve potential; cell swells

59
Q

When does the oxygen dissociation curve need to shift to the right?

A

Anaemic, metabolic acidosis, hypercapnia

60
Q

What is the structure of Hb in the foetus?

A

2 alpha, 2 gamma subunits

61
Q

How much oxygen will 1g of fully saturated Hb contain?

A

1.34 ml

62
Q

What do most dissociation curves follow?

A

Michaelis-Menten kinetics

63
Q

What dissociation curve does oxygen show?

A

Sigmoidal

Allosteric effect/ cooperative binding

64
Q

What dissociation curve does myoglobin show?

A

Hyperbolic

65
Q

What shunt forms t2,4-BPG?

A

Rapapoport Lubering shunt

66
Q

In what conditions is the Rapapoport-Lubering Shunt activated?

A

Chronic anaemia; will burrow into Hb interacting with how oxygen binds allowing increased oxygen tissue delivery

67
Q

What will shift the curve to the right?

A

Increased H+/ decreased pH
Increased 2,3-BPG
Increased temp
Increased CO2

68
Q

What are the clinical parts of the oxygen dissociation curve?

A
  1. 3 in venous blood

13. 3 in arterial blood

69
Q

What is the benefit of myoglobin and fHb?

A

At same pO2; they will bind to more O2

70
Q

What are the conditions that result in a dysfunctional red cell membrane structure?

A

Hereditary Spherocytosis

71
Q

What are the 3 main pathways in the biochem of red cells?

A

Embden-Meyerhof Pathway; anaerobic glycolysis that generates ATP and NADH (reverses metHb to Fe2+)
Hexose Monophosphate Shunt; generates NADPH, protective against oxidative stress and regenerates glutathione
Rapapoport-Lubering Shunt; generates 2,3-BPG which shift oxygen dissociation curve to right and allows more o2 to be released

Haematology (31 decks)

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