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POM > HAEM - RBC > Flashcards

HAEM - RBC Flashcards

1
Q

Haemopoiesis

A

Blood cell type production which originate in the bone marrow

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2
Q

Lineage of cells

A

Derived from pluripotent haemopoietic stem cells
They give rise to lymphoid stem cells (forming lymphocytes)
OR
Myeloid stem cells (forming erythrocytes, platelets, monocytes, mast cells, eosinophils and basophils)

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3
Q

Erythrocyte

A

Intravascular life span - 120 days
Function - oxygen transport

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4
Q

Platelet

A

10 days
Haemostasis

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5
Q

Monocyte

A

Several days
Phagocytosis + killing of micro-organisms

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6
Q

Neutrophil

A

7-10 hours
Phagocytosis + killing of micro-organisms

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7
Q

Eosinophil

A

Lifespan shorter than 7-10 hours
Defence against parasitic infection

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8
Q

Lymphocyte

A

Very variable lifespan
Humoral/cellular immunity

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9
Q

Haemopoietic stem cells characteristics

A

1) They can self-renew - continuously provide more progenitors to differentiate further (pool of HSCs not depleted) - some daughter cells remain as HSC
2) Differentiate to mature progeny

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10
Q

After HSC comes

A

Common myeloid/lymphoid progenitors

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11
Q

Platelets are

A

Broken down from megakaryocytes

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12
Q

Sites of haemopoiesis 3 weeks

A

Yolk sac ; generation of HSC (mesoderm)

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13
Q

Mesoderm

A

Middle developmental layer giving rise to skeleton, muscle, heart and bones

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14
Q

Haemopoiesis 6-8 weeks

A

Liver takes over and principle source of blood in foetus until shortly after birth

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15
Q

Haemopoiesis 10 weeks gestation

A

Children - occurs in all bones’ marrow
Adults - mainly in bone marrow of the pelvis, vertebrae and sternum

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16
Q

HSC and progenitor

A

Distributed in orderly fashion within bone marrow of mesenchymal/endothelial/vascularate

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17
Q

What is haemopoiesis regulated by

A

Genes/transcription factors/microenvironment

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18
Q

Disruption of regulation of haemopoiesis

A

Proliferation and differentiation is disrupted - lead to leuakemia/bone marrow failure

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19
Q

Haemopoietic growth factors

A

Hormones which bind to surface receptors and regulate proliferation/differentiation of HSCs

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20
Q

Red cell production

A

Erythropoiesis is regulated by erythropoietin (made in kidney)

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21
Q

Granulocyte and monocyte production?

A

Regulated by cytokines like interleukins

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22
Q

Megakaryocytopiesis and platelet production

A

Thrombopoietin

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23
Q

Lymphoid differentiation

A

Lymphoid progenitor splits into 3 :
B cell progenitor - humoral (antibody)
T cell progenitor - cellular (cytokine)
NK cell progenitor - cellular (cytokine/natural killer)

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24
Q

Myeloid differentiation

A

Common myeloid progenitor splits into two
Granulocyte-monocyte
MEP (splits into erythroid and megakaryocytic)

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25
Q

As differentiation progresses?

A

Self renewal and lineage plasticity decrease

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26
Q

Polychromatic RBCs

A

RBCs are immature - appear bluish grey

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27
Q

Reticulocytes

A

Higher RNA content (different methylene blue stain is used for this)

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28
Q

Erythropoiesis

A

Myeloid progenitor - porerythroblast - erythroblast - erythrocytes

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29
Q

4 components needed for erythropoiesis

A

Iron
Vitamin B12
Folic Acid
Erythropoietin (regulates everything)

30
Q

Low iron deficiency

A

Anaemia - microcytic (small RBC size) ; due to loss of blood (gastro/menstrual)/reduced intake/increased requirement (pregnancy) or inflammation/chronic disease

31
Q

Hookworm

A

Helminths - blood loss leading to anaemia

32
Q

What do microcytic RBCs look like

A

Hypochromic (smaler/paler)

33
Q

b12/folic acid deficiency

A

Anaemia - macrocytic (RBCs have a large size) - leads to megaloblastic anaemia - they grow but cannot divide due to lack of B12/Folic Acid

34
Q

Hypoxia

A

Oxygen is not present in sufficient amounts at tissue level to maintain adequate homeostasis

35
Q

Erythropoietin is glycoprotein synthesised in response to

A

Hypoxia so there is demand feedback loop - it stimulates bone marrow to produce more RBCs

36
Q

Iron 2 major functions

A

Oxygen transport haemoglobin
Mitochondrial proteins (cytochromes a b c for apt production)

37
Q

Iron deficiency shows

A

Koilonychia
Glossitis and Angular Stomatitis
Hypochromic and microcytic

38
Q

Where is iron absorbed

A

Duodenum

39
Q

Animal derived iron

A

Best form - ferrous - FE2+

40
Q

Iron in food (dariy/eggs etc too)

A

Ferric - Fe3+ - has to be reduced first by vitamin c for example before absorption

41
Q

Iron homeostasis

A

Excess iron is toxic to heart/liver and no way to excrete iron so tightly controlled ; 1-2mg per day is absorbed

42
Q

How is iron harmful?

A

Free radicals that can damage body tissues

43
Q

Fe3+ foods also contain

A

Phytates which bind to iron and reduce its absorption

44
Q

Iron forms/transport

A

Reduced to Fe2+ by duodenal cytochrome b ; either taken up as ferritin or in ferric form (fe3+) and transported to plasma via ferroportin

45
Q

When iron is needed for erythropoiesis

A

Bound to transferrin which delivers it to bone marrow

46
Q

Enterocytes

A

Columnar epithelial cells in gut lining

47
Q

Action of hepcidin

A

Binds to ferroportin and induces its internalisation preveting efflux of iron from enterocyte

48
Q

iron stores in cell is called

A

Ferritin

49
Q

What does hepcidin do to ferritin

A

When iron stpres are full then upregulation of hepcidin and iron absorption is limited and vice versa for when increased erythropoeisis

50
Q

Action of hepcidin

A

ACTS ON FERROPORTIN MEANING FE3+ CANNOT BE SECRETED INTO THE PLASMA FROM ENTEROCYTE
WHEN ERYTHROPOEISIS IS NEEDED THEN DOWNREGULATION OF HEPCIDIN = ALLOWING EFFLUX OF FE3+ INTO PLASMA WHICH CAN GO TO BONE MARROW (TRANSFERIN) AND CREATE RBC STEM CELLS

51
Q

Iron deficiency

A

Microcytic
Hypochromia

52
Q

How many days do rbcs circulate for

A

120 - then phagocytosed by macrophages in the spleen and haem is recycled - this is what produces bile

53
Q

Folic acid

A

Enzyme reaction : dUMP to dTTP (synthesis of thymidine)

54
Q

Vitamin B12

A

Cofactor in krebs and cofactor in regenerating tetrahydrofolate WHICH IS ESSENTIAL FOR dUMP to dTTP - so THEY ARE LINKED

55
Q

Failure of RBCs due to B12/folate deficiency

A

Megaloblastic anaemia - which is a cause of macrocytic anemia

56
Q

Folate absorbed mainly in

A

Duodenum/jejunum ; mainly from leafy greens and demand increases during pregnancy/sickle-cell anaemia where there is increased RBC production

57
Q

B12

A

Only found in foods of animal origin - cleaved from food proteins by hcl first and then binds to haptocorrins - then cleaved from this and binds to IF which is essential for absorption in the ileum

58
Q

In circulation B12 is bound to enzyme

A

Transcobalamin

59
Q

Situations of B12 deficiency

A

Vegan diet
Lack of stomach acid
Autoantibodies - production of IF disrupted - PERNICIOUS ANAEMIA
Diseases in ileum that reduces absorption

60
Q

Shortened red cell survival

A

Haemolysis

61
Q

Disruption of vertical linkages in membrane proteins

A

Hereditary spherocytosis - round with no central pallour - loss of membrane without loss of cytoplasm so membrane rounds up - removed by spleen

62
Q

Disruption of horizontal linkages

A

Hereditary elliptocytosis

63
Q

Haemolysis due to

A

Integrity of membrane
Haemoglobin structure/function
Cellular metabolism

64
Q

G6PD deficiency

A

Glucose 6 phosphate produces NADPH in PPP ; NADPH provides reducing power for maintaining reduced glutathionine which is a vital antioxidant in RBCs
G6PD maintains reducing power of NADPH that enavles glutathioine protection

65
Q

Deficiency of G6PD means

A

Red cells vulnerable to oxidant damage

66
Q

What does G6PD deficiency look like?

A

A lot of irregularly contracted cells (bite cells) - smaller and lost central pallour

67
Q

Polycythaemia

A

Too many red blood cells in circulation ; Hb/RBC/Hct all increased

68
Q

Cause 1 of Polycythaemia

A

Elevated erythropoietin levels

69
Q

Cause 2 (independent)

A

Intrinsic bone marrow disorder - myeloproliferative disorder

70
Q

Polycythaemia leads to

A

Thick blood - high viscosity which could result in thrombosis - removed via venesection

POM (12 decks)

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