Bone Marrow and Blood Cells Flashcards

1
Q

Where does haemopoiesis take place in a 0-2 month old foetus?

A

The yolk sac

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2
Q

Where does haemopoiesis take place in a 2-5 month old foetus?

A

Liver and spleen

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3
Q

Where does haemopoiesis take place in a 5-9 month old foetus?

A

Bone marrow

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4
Q

Where does haemopoiesis take place after birth?

A

Bone marrow

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5
Q

In the bone marrow of which bones does haemopoiesis take place in infants?

A

Most bones

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6
Q

In the bone marrow of which bones does haemopoiesis take place in adults?

A

Vertebrae

Ribs

Sternum

Sacrum and pelvis

Proximal end of femur

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7
Q

What is bone marrow?

A

Soft, spongy, gelatinous tissue found in the hollow space in the interior of bones

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8
Q

What does bone marrow consist of?

A

Stem cells supported by stroma

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9
Q

What is produced in bone marrow?

A

Red blood cells

Platelets

Most white blood cells

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10
Q

What are the two different types of bone marrow?

A

Red marrow

Yellow marrow

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11
Q

What tissue is the main constituent of red marrow?

A

Haemopoietic tissue

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12
Q

What tissue is the main constituent of yellow marrow?

A

Fatty tissue

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13
Q

All marrow is what type at birth?

A

Red marrow

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14
Q

What proportion of marrow is red marrow in adulthood?

A

Half

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15
Q

What happens to half of the bodies red marrow between birth and adulthood?

A

It is converted to yellow marrow

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16
Q

How can bone marrow be examined histologically?

A

By taking a trephine biopsy of the marrow in the pelvis

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17
Q

What is the starting cell for haemopoiesis?

A

Multipotent haemopoietic stem cell

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18
Q

What cells can a multipotent haemopoietic stem cell become differentiate into?

A

Common myeloid progenitor

Common lymphoid progenitor

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19
Q

A common myeloid progenitor cell can eventually differentiate into which mature blood cells?

A

Platelets

Erythrocytes (RBC)

Mast cell

Basophil

Neutrophil

Eosinophil

Macrophage

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20
Q

Under the influence of what hormone does a common myeloid progenitor cell begin differentiating to platelets?

A

Thrombopoietin

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21
Q

Thrombopoietin causes common myeloid cells to differentiate into which cell initially?

A

Megakaryocytes

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22
Q

How do megakaryocytes become platelets?

A

Increase in size

Replicate DNA

Platelets bud from cytoplasm

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23
Q

What causes megakaryocytes to produce platelets?

A

Thrombopoietin

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24
Q

What causes common myeloid progenitor cells to differentiate into red blood cells?

A

Erythropoietin

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25
Q

During the process of erythropoiesis, what cells form before becoming a red blood cell?

A

Proerythroblast

Early normoblast

Intermediate normoblast

Late normoblast (nucleated red cell)

Reticulocyte

Erythrocytes

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26
Q

What percentage of new circulating red blood cells are reticulocytes?

A

1%

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27
Q

How long before a reticulocyte matures to an erythrocyte?

A

1-2 days

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28
Q

What is the lifespan of an erythrocyte?

A

~120 days

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29
Q

What process occurs first in the production of erythrocytes?

A

Haemoglobinisation of cytoplasm

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30
Q

What process occurs secondly in production of erythrocytes?

A

Nuclear maturation

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31
Q

What process occurs lastly in the formation of erythrocytes?

A

Nuclear extrusion

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32
Q

What two different types of tissue does the spleen consist of?

A

Red pulp

White pulp

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33
Q

Describe the structure of red pulp

A

Sinuses lined by endothelial macrophages and cords

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34
Q

Describe the structure of white pulp

A

Similar structure to lymphoid follicles

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35
Q

How does blood enter the spleen?

A

Via the splenic artery

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36
Q

The splenic artery is a branch of what?

A

The celiac trunk

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37
Q

Name the other branches of the celiac trunk (not including the splenic artery)

A

Left gastric artery

Common hepatic artery

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38
Q

White cells and plasma preferentially pass through which tissue of the kidney?

A

White pulp

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39
Q

Red blood cells preferentially pass through which tissue of the kidney?

A

Red pulp

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40
Q

What can red pulp do with red blood cells?

A

Sequester them

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41
Q

List the 4 main functions of the spleen

A

Sequestration and phagocytosis

Blood pooling

Extramedullary haemopoiesis

Immunological function

42
Q

Explain sequestering and phagocytosis in relation to the spleen

A

Old/abnormal red blood cells can be sequestered by the red pulp and removed by phagocytosis

43
Q

Explain the spleens blood pooling function

A

Platelets and red blood cells can be rapidly mobilised by the spleen during bleeding

44
Q

Explain the spleens extramedullary haemopoiesis function

A

Pluripotent stem cells proliferate during haematological stress or if the marrow fails (e.g. myelofibrosis)

45
Q

Explain the spleens immunological function

A

25% of T cells and 15% of B cells are present in the spleen

46
Q

What is an enlarged spleen known as?

A

Splenomegaly

47
Q

How can splenomegaly be defined on examination?

A

Feeling the spleen below the costal margin

48
Q

How is the splenomegaly palpated for?

A

Start palpating in the right iliac fossa ( to avoid missing massive splenomegaly) and move diagonally

You will feel an enlarged spleen edge move towards your hand on inspiration

Feel for the splenic notch

Measure in cm the distance from the costal margin in the mid-clavicular line

49
Q

Give reasons for splenomegaly

A

Back pressure of blood

Over working red pulp

Over working white pulp

Conducting extramedullary haemopoiesis

Expansion due to infiltration by malignant cells (of blood origin e.g. leukaemia or metastases)

Expansion due to infiltration by other material

50
Q

What can cause back pressure of blood in the spleen?

A

Portal hypertension in liver disease

51
Q

What conditions can cause massive splenomegaly?

A

Chronic myeloid leukaemia

Myelofibrosis

Chronic malaria

Schistosomiasis

52
Q

What conditions can cause moderate splenomegaly?

A

As with massive, PLUS:

Lymphoproliferative disorders

Myeloproliferative disorders

Liver cirrhosis with portal hypertension

Infections such as glandular fever

53
Q

What conditions can cause mild splenomegaly?

A

As with massive and moderate, PLUS:

Hepatitis

Endocarditis

Sarcoidosis

SLE

54
Q

What changes to blood count can occur as a result of splenomegaly?

A

Pancytopenia or thrombocytopenia

55
Q

Define thrombocytopenia

A

Low platelet count

56
Q

Why can pancytopenia and thrombocytopenia occur in splenomegaly?

A

There can be increased pooling of blood within the enlarged spleen

57
Q

What is increased pooling of blood in the spleen known as?

A

Hypersplenism

58
Q

What is at risk of occurring when the spleen is enlarged?

A

Rupturing of the spleen

59
Q

Why is spleen rupture a risk in splenomegaly?

A

As the spleen is no longer protected by the rib cage

60
Q

Define hyposplenism

A

Lack of functioning splenic tissue

61
Q

What can cause hyposplenism?

A

Splenectomy

Sickle cell disease in older children and adults (due to multiple infarcts of the spleen followed by fibrosis)

Coeliac disease

62
Q

What is seen on a blood film in people with hyposplenism?

A

Howell Jolly bodies

63
Q

What are patients with hyposplenism at risk of?

A

Overwhelming sepsis

64
Q

People with hyposplenism are particularly at risk from sepsis caused by which types of organisms?

A

Encapsulated organisms

E.g. pneumococcus, haemophilus influenzae, and meningococcus

65
Q

Define cytopenia

A

Reduction in the number of blood cells

66
Q

Give 5 different forms of cytopenia

A

Anaemia

Leucopenia

Neutropenia

Thrombocytopenia

Pancytopenia

67
Q

Anaemia is a low count of which cell?

A

Red blood cell

68
Q

Leucopenia is a low count of which cell?

A

White blood cells

69
Q

Neutropenia is a low count of which cell?

A

Neutrophils

70
Q

Thrombocytopenia is a low count of which cell?

A

Platelets

71
Q

Pancytopenia is a low count of which cells?

A

Red blood cells, white blood cells, and platelets

72
Q

Thrombocytopenia can generally caused by an increase and decrease in what?

A

Increased removal or use

Decreased production

73
Q

What can cause increase removal or use of platelets?

A

Immune destruction

Non-immune destruction

Splenic pooling

Many drugs

74
Q

What is the most common auto-immune cause of thrombocytopenia?

A

Immune thrombocytopenic purpura (ITP)

75
Q

What immunity related problems can thrombocytopenia occur secondary to?

A

SLE

Lymphoma

CLL

76
Q

How can thrombocytopenia due to immune destruction be treated?

A

Immunosuppression (corticosteroids or pooled human immunoglobulin)

77
Q

What treatment will not work in thrombocytopenia due to immune destruction?

A

Platelets transfusion

78
Q

Why will platelet transfusion not work to treat thrombocytopenia due to immune destruction?

A

Because the transfused platelets will be destroyed also

79
Q

What non-immunity related causes can cause thrombocytopenia ?

A

Microangiopathic haemolytic states

Cardiopulmonary bypass surgery

80
Q

What can cause reduced production of platelets?

A

B12/folate deficiency

Infiltration of bone marrow by cancer/fibrosis

Aplastic anaemia

Drugs - chemotherapy, co-trimoxazole

Viruses - HIV, EBV, CMV, viral hepatitis

81
Q

What can happen as a result of thrombocytopenia?

A

Easy bruising

Petechiae, purpura

Mucosal bleeding

Severe bleeding after trauma or procedures

Intracranial haemorrhage

82
Q

Numerically define neutropenia

A

Neutrophil count <1.5x10^9/L

83
Q

Neutropenia can generally be caused by an increase and decrease in what?

A

Increased removal or use of neutrophils

Decreased production of neutrophils

84
Q

What can cause increased removal or use of neutrophils?

A

Splenic pooling

Sepsis

Immune destruction

85
Q

What can cause reduced production of neutrophils?

A

B12/folate deficiency

Infiltration of bone marrow

Aplastic anaemia

Radiation

Drugs

Viral infection

Congenital disorders

86
Q

What drugs can cause neutropenia?

A

Chemotherapy

Antibiotics

Anti-epileptics

Psychotropic drugs

Rituximab

87
Q

What can happen as a consequence of neutropenia?

A

Severe life threatening bacterial infection

Severe life threatening fungal infection

Mucosal ulceration

88
Q

Is neutropenic sepsis worrying?

A

YES - it’s a medical emergency

89
Q

What should be given immediately to someone with neutropenic sepsis?

A

IV antibiotics

90
Q

Pancytopenia can generally be caused by an increase and decrease in what?

A

Reduced production of blood cells

Increased removal of blood cells

91
Q

What can cause increased removal of RBCs, WBCs and platelets?

A

Splenic pooling due to hypersplenism

92
Q

What can cause reduced production induced pancytopenia?

A

B12/folate deficiency

Bone marrow infiltration by malignancy

Marrow fibrosis

Aplastic anaemia

Radiation

Drugs

Viruses

Congenital bone marrow failure

93
Q

What is aplastic anaemia?

A

Pancytopenia with a hypocellular bone marrow in the absence of an abnormal infiltrate and with no increase in reticulin (fibrosis)

94
Q

What kinds of malignancy can cause pancytopnenia?

A

Haematological malignancy

Non-haematological malignancy

95
Q

What haematological malignancies can cause pancytopenia?

A

Acute and chronic leukaemia

Lymphoma

Myeloma

Myelofibrosis

96
Q

What non-haematological malignancies can cause pancytopenia?

A

Prostate

Breast

Lung

97
Q

What are the symptoms of pancytopenia?

A

Symptoms of anaemia

Symptoms of thrombocytopenia

Symptoms of neutropenia

Symptoms of underlying cause

98
Q

What are the symptoms of anaemia?

A

Fatigue

Dizziness

Chest pain

SoB

99
Q

What are the symptoms of thrombocytopenia?

A

Bleeding

Bruising

100
Q

What are the symptoms of neutropenia?

A

Infection

Ulcers

Fevers