Blood Cells and Haemopoesis Flashcards Preview

Z OLD Tissues of the Body > Blood Cells and Haemopoesis > Flashcards

Flashcards in Blood Cells and Haemopoesis Deck (174):
1

Where are blood cells first produced in the foetus?

By the mesoderm and the yolk sac

2

Where are the blood cells produced after the mesoderm of the yolk sac?

By the liver and spleen, and then finally by the bone marrow

3

Where do all the cellular components of the blood arise from?

Stem cells

4

What are stem cells capable of?

Division and differentiation

5

What two main lines develop from stem cells?

#NAME?

6

What is meant by ‘blasts’?

Cells capable of division

7

What are myeloid blasts the precursors of?

- Erythrocytes 
- Granulocytes 
- Monocytes
- Platelets

8

What are erythrocytes?

Red cells

9

What are granulocytes?

White cells with granules in the cytoplasm

10

What are monocytes?

Macrophage precursors

11

What are lymphoblasts the precursors of?

Lymphocytes

12

What happens to lymphocytes once they have been produced?

They leave the bone marrow, and some pass through the thymus

13

What happens to lymphocytes that pass through the thymus?

They transform into T cells

14

What can T cells do?

Some can kill virus infected cells in cellular immunity

15

What do B cells do?

Produce antibody molecules responsible for humoral immunity

16

Where can further division of differentiation of lymphocytes occur?

In lymph nodes and lymphoid aggregates throughout the body

17

Where are early blood cells held?

In the bone marrow

18

What holds early blood cells in the bone marrow?

Adhesion molecules

19

Give 2 examples of adhesion molecules

- Collagen 
- Fibronectin

20

What happens as blood cells mature?

The adhesion molecule receptors on their surface downregulate, leading to the release of mature cells into circulation

21

What regulates the rate of division and differentiation of blood cells?

Various growth factors known as cytokines

22

What is the function of red blood cells?

- To carry oxygen from the lungs to all the tissues of the body
- To transport CO 2  back to the lungs

23

What is RBC production regulated?

By a feedback system which increases the production of erythropoietin form peritubular endothelial cells in the kidney in response to hypoxia

24

What does erythropoietin do?

Increases the rate of RBC production and release from teh bone marrow, thereby increasing oxygen carrying capacity of the blood

25

How is oxygen carried in RBC?

Bound to haemoglobin

26

What does haemoglobin consist of?

4 globin chains (2 α and 2 ß)

27

What does each globin chain carry?

A haem molecule

28

What does each haem molecule do?

Binds to oxygen

29

Are globin chains tightly or loosely bound?

Loosely

30

What does globin chain interaction depend on?

Oxygen tension

31

What is the end effect of haem binding?

A very efficient oxygen dissociation curve

32

What is the oxygen dissociation curve of haemoglobin so effective?

Because oxygen is more tightly bought in areas of high oxygen tension, and more readily released in areas of low oxygen tension

33

How long does the average RBC survive for?

120 days

34

What happens when a RBC has reached the end of its lifespan?

It is broken down, with other abnormal RBCs, in the lvier and spleen

35

What happens to the components of RBC on breaking down?

- The iron is recycled 
- The protoporphyrin of haem is metabolised to bilirubin

36

What are leucocytes?

Nucleated cells which circulate in the blood

37

What do leucocytes include?

- Neutrophils 
- Eosinophils 
- Basophils 
- Monocytes
- Lymphocytes

38

What do mature neutrophils have?

Multi-lobed nucleus and small granules in the cytoplasm

39

What is the function of neutrophils?

To migrate out of the circulation to a site of infection and destroy foreign material by phagocytosis

40

What is the process of migration to site of infection known as?

Chemotaxis

41

What does chemotaxis occur in response to?

Chemotactic substances released by bacteria or other white cells already presented in the infected or damaged tissue

42

What do some cytokines do regarding neutrophils?

- Increase neutrophil production 
- Increase chemotaxis and phagocytosis

43

Give an example of a cytokine that has an influence on neutrophils?

G-CSF

44

How long does the average neutrophil survive?

About 10 hours

45

What do eosinophils have?

Bilobed nucleus and orange granules

46

What do eosinophils do?

- Phagocytosis 
- Release cytotoxic enzymes

47

What is the purpose of the cytotoxic enzymes released by eosinophils?

To damage larger particles

48

What are numbers of eosinophils increased in association with?

Allergic reaction and atopy

49

What do basophils have?

Many large, dark purple granules

50

What do basophils do?

Mediate acute inflammatory reactions

51

What do mediatory basophils include?

Heparin and histamine

52

Describe a monocyte

Large, with folded nucleus, grey/blue cytoplasm and occasional vacuoles

53

When can monocytes move out of circulation?

After 20-40 hours

54

What happens once monocytes have moved out of the circulation?

They migrate to become macrophages in many other oragans in the body

55

What are macrophages known as in the liver?

Kupffer cells

56

What are macrophages known as in the brain?

Glial cells

57

What do monocytes do?

Chemotaxis, moving towards areas of infection, inflammation or neoplasm. Can phagocytose and interact with T cells

58

Describe lymphocytes

Small cells, with round nucleus and rim of pale blue cytoplasm

59

What % of lymphocytes are T?

75%

60

What are T lymphocytes responsible for?

Cellular immunity

61

What are T lymphocytes processed by?

Thymus

62

What cells are released from lymphocytes?

Only those which can recognise self-histocompatibilty molecules (HLA- human leucocyte antigens), but not react against them

63

What are helper cells?

T cells expressing CD4 on their surface

64

What do helper cells do?

Recognise antigens attached to HLA class II molecules, and stimulate cytotoxic cells

65

How to helper cells stimulate cytotoxic cells?

By expressing CD8

66

What does CD8 expression do?

Recognises and kills virally infected host cels

67

What does CD4-expressing helper T cells permit?

The transformation of B cells to plasma cells

68

What are B lymphocytes responsible for?

Humoral immunity

69

What can B cells be stimulated by?

Antigens

70

What happens to B cells on stimulation with antigens?

They transform into immunoblasts, and then plasma cells

71

What do plasma cells do?

Secrete immunoglobulins

72

What are immunoglobulins?

Antibody molecules

73

What are platelets?

Small round blue particles

74

What produces platelets?

The cytoplasm of megakaryocytes in the bone marrow

75

What do platelets have?

- Cytoplasm containing alpha granules and dense granules 
- Complex surface membrane

76

What do alpha granules contain?

Fibrinogen, von Willebrand’s Factor and other large molecules

77

What do dense granules contain?

Small molecules such as ADP and calcium

78

What does platelet activation result in?

Adhesion to damaged cell wall and aggregation with other platelets

79

What to platelets present?

A phospholipid surface

80

What is the purpose of the presentation of the phospholipid surface by platelets?

Provides binding sites for clotting factors during the activation of the clotting cascade

81

What is blood classified as?

A loose connective tissue

82

What are the two main parts of blood?

#NAME?

83

Give two examples of the formed elements of blood

- Blood cells 
- Platelets

84

What is the liquid phase of blood called?

Plasma

85

How does plasma appear histologically?

Structureless, homogenous

86

What % of blood volume does plasma constitute?

55%

87

What are the cells of the blood called?

Blood corpuscles

88

What are the two types of blood corpuscles?

#NAME?

89

What are leucocytes further classified into?

- Polymorphonucleur granulocytes 
- Agranulocytes

90

What are polymorphonucleur granulocytes?

Cells whose nuclei are lobed, and whose cytoplasm is filled with granules

91

What are agranulocytes?

Cells having normal looking nucleus and cytoplasm, free of granules

92

What does the blood contain in addition to these corpuscles?

Platelets

93

Does a mature erythrocyte possess a nucelus?

No

94

What shape in a mature erythrocyte?

A biconcave disc, about 7.5µm in diameter

95

Why do erythrocytes often appear circular in blood smears?

They are often orientated ‘face on’

96

What must be true for an erythrocytes true form to be seen in micrographs?

The film must be sufficiently thick for them to be seen in lateral profile

97

What is an important characteristic of erythrocytes?

They are extremely flexible

98

What is the advantage of erythrocytes being extremely flexible?

They can pass through the smallest of blood vessels, the capillaries, whose diameter may be less than theirs

99

What are a small proportion of red blood cells known as?

Reticulocytes

100

How much of the circulating RBCs are known as reticulocytes?

1%

101

What are reticulocytes?

Newly formed RBC which have only just been discharged into the blood from the bone marrow

102

What stain is used for blood smears?

Leishmanns

103

What should be looked for when inspecting a blood smear?

- Scan the slide for even cell distribution 
- Avoid periphery of slide as spread is too thick where the drop of blood was placed, and too thin where the cells are widely dispersed where smear ended

104

What shape are polymorphonuclear granulocytes?

Round

105

How big are polymorphonuclear granulocytes?

10-12µm

106

What do polymorphonuclear granulocytes have?

A nucleus which has 2-5 lobes
Cytoplasmic granules

107

What are the polymorphonuclear granulocytes classified as?

- Neutrophils 
- Eosinophils 
- Basophils

108

What are the most numerous of the granulocytes?

Neutrophils

109

How do neutrophils appear?

Pale cytoplasm containing very indistinct granules

110

What kind of cells are neutrophils?

Phagocytic

111

What do histological methods show regarding neutrophils?

The granules are actually lysosomes containing digestive enzymes

112

How long do neutrophils cells last?

Short lived

113

What happens to neutrophils?

They become pus cells

114

Where are gross accumulations of pus cells visible?

In abscesses as pus

115

What are neutrophils able to do?

Migrate through the walls of the blood vessels to reach sites where their phagocytic action is required

116

How do eosinophils appear?

They have a cytoplasm which is completely filled with large granules which stain red

117

Describe the properties of eosinophils

- Highly mobile 
- Weakly phagocytic

118

What do eosinophils ingest?

Antigen-antiobdy complexes

119

What is the result of eosinophils ingesting antigen-antibody complexes?

The blood level of eosinophils is abnormally high in allergic conditions such as asthma or hay fever

120

What are the least common cells in blood?

Basophils

121

What is the most distinctive feature of basophils?

Their granules stain intensely blue

122

What do basophil granules contain?

Heparin, serotonin and histamine

123

What do basophils resemble?

Mast cells

124

What are basophils concerned with?

The inflammatory response

125

When are basophils released into the tissue?

After local tissue damage, released into site of injury

126

What does histamine cause?

Vasodilation and leakage of fluid into the tissues (oedema)

127

What does heparin do?

Prevents clotting of the blood

128

What are the two types of agranulocytes found in the circulating blood?

Monocytes and lymphocytes

129

What system to monocytes belong to?

Macrophage

130

What kind of cells are monocytes?

Actively phagocytic

131

How big are monocytes?

Largest cell in peripheral blood, being almost twice the size of neutrophils

132

Describe the nucleus of monocytes

Classified as mononuclear cells, but the nucleus irregular in shape, often kidney-shaped and so indented that it may appear to be lbed

133

What differentiates monocytes from lymphocytes?

Monocytes have abundant cytoplasm

134

Does monocytes have lysosomes?

Yes, they are present in the cytoplasm, but are barely visible under the light microscope

135

What are the main characteristics on monocytes?

Their mobility and phagocytic power

136

What is meant by the motility of monocytes?

They readily pass through the walls of the smallest blood vessels into the surrounding tissues

137

What are monocytes known as once they are in the tissue?

Histiocytes (tissue macrophages)

138

What happens to monocytes when the immune reaction subsides?

They may return to the circulation

139

Describe the appearance of lymphocytes

They have a very high nucleo-cytoplasmic ratio, with a thin rim of cytoplasm evident around the nucleus 
Under the electron microscope, small cytoplasmic projections are visible on the surface

140

What is different about larger lymphocytes?

The cytoplasm is more abundant

141

How does the nuclear chromatin of lymphocytes stain?

Darkly, usually clumped appearance

142

What does the identification of different lymphocyte subsets require?

The use of monoclonal antibodies

143

What do small lymphocytes do?

They are actively mobile cells, which can pass between endothelial cells lining the blood vessels and thus enter adjacent tissues

144

How is the presence of accumulation of lymphocytes in various tissues explained?

By their migration out of the circulation

145

Where by aggregations of lymphocytes be found?

In certain chronic inflammatory states and around skin grafts

146

What happens to lymphocytes that have left the circulation?

They return to the main blood stream by way of the lymphatic system

147

What is the importance of the lymphocytes?

They are a fundamental part of the adaptive immune response to foreign materials

148

What are the smallest cells in the blood?

Blood platelets (thrombocytes)

149

Do platelets have nuclei?

No

150

How do platelets tend to occur?

In groups

151

How do platelets appear in blood smears?

Centre appears dark purple, while periphery may be lighter in colour

152

What is the function of platelets?

To assist in clotting (coagulation or thrombosis) or blood

153

What are platelets rich in?

- Compounds which cause constriction of blood vessel walls 
- Phospholipid factor III

154

What compound causes constriction of blood vessel walls?

Serotonin

155

Where do platelets accumulate?

At sites of injury

156

What do platelets do at sites of injury?

Release serotonin to cause constriction

157

What are platelets responsible for?

Forming the clot or thrombus

158

What does phospholipid factor III do?

Activates prothrombin into thrombin

159

What does thrombin does?

Converts soluble fibrinogen to insoluble fibrin in blood

160

What does blood plasma contain?

Large number of substances such as proteins (albumins, globulins and fibrinogen), and traces of mineral ions, all of which are dissolved in water.  Also contains minute fat globules (chylomicrons) and small particles of broken down blood corpuscles

161

What % of plasma does water constitute?

90%

162

What are the stages of haemopoiesis?

Proliferation 
Differentiation

163

What happens in proliferation?

Starting with a stem cell, the cell divides into two

164

Why does the stem cell divide into two in proliferation?

One to replace the original stem cell (self-renewal), and one that differentiates

165

What happens in the differentiation stage of haemopoiesis?

The haemopoietic progenitor will first differentiate to form either a myeloid blast or a lymphoid blast

166

What do myeloid blasts go on to be?

RBC, WBC or platelet

167

What do lymphoid blasts go on to be?

Immuneresponse cells

168

What does the progenitor cell differentiate into under the influence of?

A particular cytokine

169

What is eryhtropoiesis controlled by?

Partial pressure of oxygen

170

What does a low partial pressure of oxygen stimulate?

Increase in erythrypoietin

171

What is the life span of a red blood cell?

120 days

172

What shape is a RBC?

Biconcave, flexible disc

173

What is the purpose of the shape of RBCs?

It facilitates the passage through microcirculation

174

Describe the process of haem catabolism?

- Red blood cells are broken down into haemoglobin 
- Haemoglobin is broken down into haem 
- Haem is broken down in bilirubin 
- Bilirubin passes into the liver 
- Once in liver, bilirubin either passes to kidney, or to gall bladder through bile duct to small intestine. 
- If in small intestine, bilirubin passes down to large intestine, and is either converted to stercobilin or urobilinogen 
- Stercobilin continues down large intestine 
- Urobilirubin is passed to kidney and excreted