Red Blood Cells Flashcards

1
Q

What do all blood cells originate from?

A

Haematopoetic stem cells

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2
Q

Where does foetal haematopoeisis start?

A

The yolk sac

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3
Q

Which bones in children does haematopoiesis occur in?

A

All bones

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4
Q

Which bones in adults does haematopoiesis occur in?

A

Long bones - femur, pelvis, sternum

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5
Q

What are the two characteristics of HSC?

A

The can self renew and they can differentiate

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6
Q

What are the two cells that HSC differentiate into?

A

Common Lymphoid Progenitor and Common Myeloid Progenitor

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7
Q

What is the intravascular life span of red blood cells?

A

120 days

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8
Q

Where does erythropoiesis occur?

A

Bone Marrow

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9
Q

What is HAEM iron also known as?

A

Ferrous iron - fe2+

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10
Q

What is non-HAEM iron also known as?

A

Ferric iron - fe3+

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11
Q

What affect do phytates have on iron absorption?

A

They reduce it

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12
Q

What organs is excess iron toxic to?

A

Heart and liver

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13
Q

Where is ferroportin found?

A

In duodenum enterocytes

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14
Q

How do we lose iron if it is high?

A

Higher iron leads to HEPCIDIN release, which blocks ferroportin, so iron cannot leave the enterocytes. Therefore when the enterocyte is destroyed so is the iron stored within it

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15
Q

What does inflammation do to Hepcidin?

A

Increases hepcidin, and therefore can lead to anaemia of inflammation as there is not enough iron in the blood as it is all being kept within the enterocytes

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16
Q

Why do we need Folate and Vitamin B12?

A

They are needed for dTTP synthesis - thymidine, needed for DNA synthesis

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17
Q

What can a Vitamin B12 and Folate deficiency cause?

A

Megaloblastic erythropoiesis - this is because the cells keep dividing but lack the DNA

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18
Q

Name three sources of Folate

A

Green leafy vegetables, cauliflower and Brussels sprouts

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19
Q

Name three sources of B12

A

Meat, fish, clams

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20
Q

What does B12 combine with so it can be absorbed?

A

Intrinsic factor which is made in the gastric parietal cells

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21
Q

What causes vitamin B12 deficiency

A

Inadequate intake, pernicious anaemia and malabsorption

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22
Q

What is pernicious anaemia?

A

This is where your body does not make IF therefore the B12 cannot bind and therefore cannot be absorbed

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23
Q

Why do red blood cells have a life span of 120 days?

A

When they move through capillaries and blood vessels, the walls bend and stretch meaning they get damaged

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24
Q

Where are the red blood cells destroyed?

A

Spleen

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25
Q

What are the RBCs broken down into?

A

HAEM and globin

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26
Q

What does the HAEM part of the RBC after it is destroyed?

A

Gets broken down into bilirubin

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27
Q

How is bilirubin excreted

A

In bile

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28
Q

Why is bile important

A

Contains bile salts which are needed for the emulsification of fats so they can be absorbed

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29
Q

What are the three types of granulocytes

A

Neutrophil, basophils and eosinophil

30
Q

What does hypochromia mean?

A

Too little haemoglobin so pale

31
Q

What is a polychromatic RBC?

A

One that is too read due to too much haemoglobin

32
Q

What are target cells?

A

When you have an accumulation of hemoglobin in the area of central pallor

33
Q

What causes the presence of target cells?

A

Jaundice, liver disease, hyposplenism

34
Q

What does anisocytosis mean

A

Variation in size

35
Q

What does poikilocytosis mean

A

Variation in shape

36
Q

What causes sickle cells?

A

Due to the polymerisation of HbS which forms tachtoids that distort the shape of the RBC

37
Q

What is the mutation that causes sickle cell disease? SICKLE CELL SIX GIVES ME A CRISIS

A

Charged glutamic acid residue at positive 6 in beta Hb gene is replaced by uncharged valine

38
Q

“Normal” Hb is determined by many things like..

A

Gender and physiological status eg altitude

39
Q

What type of distribution fo Hb concentrations show?

A

Gaussian distribution

40
Q

An infant with sickle cell anaemia (HbSS) develops symptoms of fatigue and pain. Blood tests reveal anaemia with thrombocytopenia. Examination reveals a mass on the left-hand side of his abdomen. Given this information, what could be the most likely explanation for his symptoms?

A

Pooling of blood in the spleen - spleenic sequestration

41
Q

What is Crohn’s Disease?

A

inflammatory bowel disease which often involves ulcer formation in the mucosal layer of the intestines.

42
Q

How can Crohn’s disease lead to iron-deficiency anaemia?

A

Crohn’s disease can lead ulcer formation in the stomach, meaning internal bleeding can occur. This may result in iron-deficiency anaemia due to blood loss

43
Q

What regulates the proliferation and differentiation of Haematopoietic stem cells?

A

Haematopoietic growth factors

44
Q

A 28-year old female has some tests carried out following a full blood count that subsequently reveal that she is folate deficient. What changes in the red blood cells would you expect to see.

A

Macrocytic cells

45
Q

Which cells do myeloid stem cells give rise to?

A

Red blood cells, granulocytes, monocytes, mast cells and basophils

46
Q

What is the life span and function of a platelet?

A

10 Days - Haemostasis

47
Q

What is the life span and function of a monocyte?

A

Several days, defense against infection by phagocytosis

48
Q

What is the life span and function of a neutrophil?

A

7-10 hours - defense against infection by phagocytosis and killing of micro-organisms

49
Q

At what point does the liver take over haematopoiesis in the foetus?

A

6-8 weeks gestation

50
Q

What are haematopoietic growth factors?

A

Glycoprotein hormones which bind to cell surface receptors
Regulate proliferation and differentiation of HSCs
Regulate function of mature blood cells

51
Q

What is the haematopoietic growth factor which influences red cell production?

A

Erythropoietin

52
Q

What are the haematopoietic growth factors which influence granulocyte and monocyte production?

A

G-CSF, G-M CSF, cytokines e.g. interleukins

53
Q

Which common progenitor do megakaryocytes derive from?

A

Myeloid

54
Q

What are three causes of microcytic anaemia?

A

Iron deficiency
Pregnancy
Childhood

55
Q

What are three causes of macrocytic anaemia?

A

(B12/folate deficiency)- alcohol excess, pregnancy, vegan diet

56
Q

What are the two main functions of iron?

A

Oxygen transport in haemoglobin
Mitochondrial proteins
cytochromes a, b and c: for production of ATP

57
Q

Why is ferric iron not as easily absorbed?

A

and requires action of reducing substances (e.g. vitamin C) for absorption

58
Q

How does anaemia of chronic disease/inflammation occur?

A

Pro-inflammatory cytokines such as IL-1, TNF-alpha, IL-6 and IFN-gamma work to decrease EPO production, and increase hepcidin - increased hepcidin means less iron absoprtion in the gut as hepcidin binds to ferroportin, meaning iron is unable to leave theenterocytes and therefore is destroyed when the entoercytes die

59
Q

When is hepcidin released?

A

Released from the liver in response to high storage iron

60
Q

What can cause a deficiency in B12?

A

inadequate intake e.g. veganism
- inadequate secretion of IF: pernicious anaemia (an autoimmune disorder)
Malabsorption e.g. coeliac disease
lack of acid in stomach (achlorhydria)

61
Q

During what situations do the requirements for folic acid increase?

A

During pregnancy and during red cell production

62
Q

What three things does erythrocyte function depend on?

A

Integrity of the membrane
Haemoglobin structure and function
Cellular metabolism

63
Q

What structures help t maintain the integrity and shape of the red cell?

A

The red cell membrane - made of lipid bilayers which is supported by proteins and contains transmembrane proteins

64
Q

What are the transmembrane proteins found in red cell membrane?

A

Band 3 and rhesus

65
Q

What are the skeletal proteins found in red blood cells membrane?

A

Spectrin and junctional

66
Q

What does a disruption to vertical linkages in the red blood cell membrane cause?

A

Hereditary Spherocytosis

67
Q

What would be seen on a blood film of a patient with hereditary spherocytosis?

A

Rounded, with a regular outline and lacking central pallor

68
Q

Disruption of horizontal

linkages in red cell membrane produces…

A

Hereditary elliptocytosis

69
Q

How does deficiency in G6PD affect red cells?

A
  1. G6PD is an important enzyme in the HMP shunt
  2. The HMP shunt is involved in metabolism of glutathione which protects the red cell from oxidant damage
  3. Therefore deficiency of G6PD causes red cells to be vulnerable to oxidant damage
70
Q

What protects the red cells from oxidant damage?

A

Glutathione

71
Q

What does G6PD deficiency cause?

A

G6PD deficiency usually causes intermittent, severe intravascular haemolysis as a result of infection or exposure to an exogenous oxidant

72
Q

What are episodes of intravascular haemolysis associated with the appearance of?

A

considerable numbers of Irregularly contracted cells/ ‘bite cells’