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POM (Principles of Medicine) > Red cells > Flashcards

Red cells Flashcards

1
Q

What is haemopoiesis?

A

Production of erythrocytes, platelets, megakaryocytic and leukocytes

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2
Q

What substance influences the production of erythrocytes?

A

Erythropoietin

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3
Q

What are granulocytes?

A

Basophils, neutrophils, eoisinophils

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4
Q

What factors stimulate granulocyte formation?

A

Granulocyte cologne stimulating factors (G-CSF);

GM-CSF (Granulocyte-macrophage stimulating factor)

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5
Q

What factor stimulates platelet formation?

A

Thrombopoietin

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6
Q

What cells are multipotent?

A

Myeloid progenitor cells

Lymphoid progenitor cells

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7
Q

What is the function of erythrocytes?

A

Oxygen transport

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8
Q

What is the function of neutrophils?

A

Inflammation, phagocytosis of pathogens

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9
Q

What is the function of eosinophils?

A

Defence against parasitic infection?

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10
Q

What is the function of platelet?

A

Haemostasis

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11
Q

What is WBC?

A

White blood count, number of white blood cells in a given volume

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12
Q

What is RBC?

A

Number of red blood cells in a given volume

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13
Q

What is Hb?

A

Haemoglobin concentration

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14
Q

What is Pcv?

A

Mean packed volume proportion of centrifuged blood occupied by red cells

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15
Q

What is Hct?

A

Haematocrit, equivalent to PCV

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16
Q

What is MCV?

A

Men cell volume, the average size of red cells

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17
Q

What is MCH?

A

Mean cell haemoglobin, average amount of haemoglobin in a red cell

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18
Q

What is MCHC?

A

Mean cell haemoglobin concentration, the average concentration of haemoglobin in red cell

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19
Q

What is platelet count?

A

The number of platelets in a given volume of blood

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20
Q

What do myeloid progenitor cells give rise to during erythropoiesis?

A

Proerythroblasts –> erythroblasts –> eryhthrocytes

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21
Q

In respinse to cellular hypoxia , which hormone is released to stimulate erythropoeisis?

A

Erythropoeitin

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22
Q

Where is erythropoietin synthesised and released from?

A

Kidney

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23
Q

What other hormone stimulates release of erythropoietin?

A

Testosterone

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24
Q

Which cells secrete erythropoietin?

A

Juxtatubular cell association with the particular capillary and proximal convoluted tubule

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25
Q

Which factors stimulates the synthesis of erythropoietin?

A

Hypoxia-inudicble factors

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26
Q

Which receptors does erythropoeitin bind onto?

A

Epo receptors

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27
Q

What proteins carry oxygen in RBCs?

A

Haemoglobin

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28
Q

How is the prophetic haem group arranged?

A

Haem group is bound to ferrous group held in porphyrin ring

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29
Q

What are the adaptations of RBCs?

A

Thin cell membranes reduces diffusion pathway for oxygen molecules
No nucleus: Maximum storage capacity of Hb
Biconcave shape: Increases
SA:V ratio

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30
Q

What is the structure of haemoglobin?

A

Conjugated globular protein with quaternary structure of 2 alpha and 2 beta polypeptide chains.
Each chain is arranged around a haem group.
primary structure: Pseudo-repeating sequence of amino a

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31
Q

Why are haemoglobin molecules soluble?

A

Hydrophillic and hydrophobic interactions , polarised amino acid variable groups exposed externally, potential to form hydrogen bonds with water,

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32
Q

Why is Hb Susceptible too denaturation?

A

No covalent or disulphide bonding between chains, therefore weakly linked.

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33
Q

How does haemoglobin bind to oxygen?

A

Iron enables haemoglobin to bind and release oxygen molecules, changing shape to the polypeptide chains (conformational change).

34
Q

What form of iron is absorbed in duodenum?

A

Ferrous (Fe2+)

35
Q

What form is non-haem iron presented in?

A

Ferric (Fe3+)

36
Q

What reducing substances convert ferric iron to ferrous?

A

Vitamin c, ascorbic acid

37
Q

Which molecules reduce absorption of iron?

A

Phytates

38
Q

Why is excess iron toxic?

A

Free radicals , no physiological excretion of iron

39
Q

What molecules does hepcidin bind onto?

A

Ferroportin (Iron export protein)

40
Q

What is ferroportin?

A

Iron export protein

41
Q

What happens to ferroportin upon hepicidin binding?

A

Internalisation of ferroportin, ferrous iron is thereby sequestered within the enterocyte prevents efflux of iron

42
Q

Where does hepicidin act?

A

Gut, enterocytes

43
Q

How is hepcidin synthesis suppressed?

A

Erythropoietic activity, ensuring iron supply by increasing ferroportin in the duodenum enterocyte (maximising iron absorption)

44
Q

What happens to hepcidin synthesis during elevated iron levels?

A

Increases hepcidin synthesis, therefore iron sequestration increases, ferroportin degrades

45
Q

What is the role of macrophages in iron regulation?

A

Macrophages release iron that recycle in the spleen; dietary absorption in the duodenum, releases iron from storage in hepatocytes

46
Q

How is hepcidin influenced during inflammation?

A

Hepcidin production is stimulated, and iron entry into plasma is inhibited causes hypoferrenia and anaemia

47
Q

How is iron reduced to Fe2+?

A

Duodenal cytochrome b binds to divalent metal transporter on apical membrane.

48
Q

how is iron stored?

A

Iron is stored as ferritin or oxidised

49
Q

How is iron delivered to the bone marrow?

A

Plasma iron bound to transferrin

50
Q

What is the function of b12 and folate?

A

Necessary for the synthesis of thymidine, thus deficiency will result in the inhibition of DNA synthesis

51
Q

Why do erythroblasts require B12 & folate?

A

Required for proliferation during differentiation

52
Q

What happens during b12 and folate deficiency?

A

Inhibits purine and thymidylate syntheses, impairs dan synthesis and causes erythroblast apoptosis

53
Q

What condition occurs during b12 deficiency?

A

Megaloblastic erythropoiesis, macrocytosis

54
Q

What is the purpose of B12?

A

Cofactor for the conversion of methyl-malonyl Coa to succinylcholine CoA

55
Q

How is B12 absorbed?

A

Hydrochloric stomach acid releases B12
B12 combines with haptocorrin, cleaved by and bound to instrinsic factor
B12-IF Complex traverses into the small intestine, binds to ileum receptors
Taken up by enterocyte and bound to trans cobalamin-II

56
Q

What molecule does B12 combine with within the stomach?

A

Haptocorrin

57
Q

What molecule cleaves haptocorrin?

A

Intrinsic factor

58
Q

What cells secrete Intrinsic factor?

A

Gastric parietal cells

59
Q

How is b12-IF complex taken up?

A

By enterocyte

60
Q

how is b12 stored in the liver and transported?

A

Transcobalamin-II

61
Q

Where is folate absorbed?

A

Duodenum & Jejunum

62
Q

What are the causes for vitamin B12 deficiency?

A

Inadequate intake of sources containing B12 (Veganism)
Lack of stomach acid (Achlorhydria)
Inadequate secretion of intrinsic factor
Malabsorption

63
Q

How are erythrocytes destroyed?

A

Phagocytic cells of the spleen; phagocytic vacuole envelops ingested RBC, lysosome hydrolytic ally digests cell into haem and globin components

64
Q

What are phagocytic cells of the spleen named as?

A

Splenic reticuloendothelial macrophages

65
Q

What is the fate of globin?

A

Hydrolysed into amino acids, and returned to bone marrow for erythropoiesis

66
Q

What is transferrin?

A

Iron binding glycoproteins and is transported to the bone marrow to be incorporated into the synthesis of erythrocytes

67
Q

What are the two iron storage molecules?

A

Ferritin and hemosiderin

68
Q

What is the fate of the non-iron portion of haem?

A

Biliverdin converted into bilirubin, binds to albumin and travers to liver to produce bile

69
Q

What happens to circulating bilirubin?

A

Kidneys remove and secrete into urine

70
Q

What is microcytic anaemia?

A

RBC are comparatively smaller than the standard, anaemia with the small red cells (Microcytosis)

71
Q

What is normocytic anaemia?

A

RBC normal in size, anaemia

72
Q

What is macrocytosis?

A

Anaemia with cells larger than standard

73
Q

What is hypochromia?

A

Cells have larger area of central pallor than normal, due to lower haemoglobin content and concentration; flatter cell

74
Q

What is polychromatic?

A

Blue tinge associated to the cytosol of an erythrocyte, indicates young cell, polychromatic cells are larger than; cause of macrocytosis

75
Q

What is reticulocytosis?

A

New methylene blue can be applied to reticulocytes, associated with high RNA content

76
Q

What is anisocytosis?

A

Illustrates variation in size than the standard

77
Q

What is poikilocytosis?

A

variation in shape

78
Q

What are the different shapes in RBCs?

A

Spherocytes, irregularity contracted cells, sickle cells, target cells, ellioptocytes and fragments

79
Q

What are target cells?

A

Accumulation of haemoglobin in the centre of the area of central pallor

80
Q

What codon mutation is concerned with sickle cell?

A

Codon no/6, charged glutamic acid into uncharged valine

POM (Principles of Medicine) (34 decks)

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