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Flashcards in Infection and Immunity Anatomy Deck (114):
1

Where is the thymus gland found?

In the thorax in the anterior mediastinum

2

Where does the thymus gland lie?

Posterior to the sternum, and anterior to the pericardium

3

What happens to the thymus gland as we age?

It gradually enlarges during childhood, but after puberty undergoes a process of involution

4

What is the result of the process of involution on the thymus gland?

Reduciton in the functioning mass of the gland

5

When does the thymus gland cease to function?

It doesn't- it continues to function throughout life

6

Label this diagram

  • A - Fourth thoracic vertebra
  • B - Right pulmonary artery
  • C - Tracheobronchial lymph nodes
  • D - Transverse pericardial sinus
  • E - Left atrium
  • F - Oblique pericardial sinus
  • G - Thoracic duct
  • H - Spinal cord
  • I - Oesophagus
  • J - Inferior vena cava
  • K - Descending aorta
  • L - Diaphragm
  • M - Pericardial cavity
  • N - Right atrium
  • O - Right ventricle
  • P - Ascending aorta
  • Q - Sterum
  • R - Thymus
  • S - Transverse thoracic plane
  • T - Arch of aorta
  • U - Left brachiocephalic vein
  • V - Branchiocephalic trunk
  • W - Trachea

7

What is the thymus gland arranged into?

Outer cortex and inner cortex

8

How does the outer cortex differ from the inner medulla?

It is more cellular

9

What does the inner medulla of the thymus gland havw?

Hassall's corpuscles

10

What are Hassall's corpuscles?

Aggregated thymic epithelial cells

11

What is the cellular composition of the thymus gland?

  • Lymphoid cells
  • Macrophages
  • Other supporting cells
  • Epithelial cells

12

Describe the epithelial cells in the thymus gland

Have different appearances in different loations within the gland

13

What do the epithelial cells of the thymus gland form?

A continuous sub-capsular layer and network in the cortex and medulla

14

What happens to the thymus epithelial cells deep in the medulla?

They are aggregated into Hassall's corpuscles

15

Describe the passage of cells through the thymus gland during the process of T cell maturation

Immature T cells enter the cortex and proliferate, mature and pass on to the medulla. From the medulla, mature T lymphocytes enter the circulation

16

What is the lymphoid system?

An 'overflow system'

17

What does the lymphoid system provide?

Drainage of surplus tissue fluid and leaked plasma proteins to the bloodstream, and removal of debris from cellular decomposition and infection

18

What are lymphatic plexuses?

Networks of lymphatic capillaries that originate blinding in the extracellular spaces of most tissues

19

What are the lymphatic vessels?

A nearly body-wide network of vessels

20

Describe the structure of lymphatic vessels

Thin walled, abundant lymphatic valves

21

Where do lymphatic capillaries and vessels occur?

Almost everywhere blood capillaries are found

22

Where are lymphatic capillaries are vessels not found?

  • Teeth
  • Bone
  • Bone marrow
  • CNS

23

What are lymph nodes?

Small masses of lymphatic tissue

24

Where are lymph nodes located?

Along the course of lymphatic vessels

25

What happens at lymph nodes?

Lymph is filtered on it's way to the venous system

26

What are lymphoid organs?

Parts of the body that produce lymphocytes

27

Give 5 lymphoid organs

  • Thymus
  • Red bone marrow
  • Spleen
  • Tonsils
  • GALT

28

What is lymph?

The tissue fluid that enters lymph capillaries and is conveyed by lymphatic vessels

29

Describe the appearance of lymph

Usually clear, watery, and slightly yellow 

30

What do superficial lymph nodes drain into? 

Deep lymph nodes

31

What do deep lymph nodes do? 

Join to form lymphatic trunks 

32

What do lymphatic trunks do? 

Unite to form either the right lymphatic duct or the thoracic duct 

33

What does the right lymphatic duct drain into? 

The junction of the right subclavian and right internal jugular veins (right venous angle) 

34

Where does the thoracic duct drain? 

Into the junction of the left subclavian and left internal jugular veins (left venous angle) 

35

Label this diagram

  • A - Area draining to right lymphatic duct (pink) 
  • B - Right and left venous angles 
  • C - Deep cervical nodes 
  • D - Right lymphatic duct 
  • E - Right subclavian vein 
  • F - Central and posterior axillay nodes 
  • G - Deep lymphatic vessels 
  • H - Cubital nodes 
  • I - Deep inguinal nodes 
  • J - Superficial inguinal nodes 
  • K - Iliac nodes 
  • L - Lumbar (caval/aortic) nodes 
  • M - Lymphatic trunks 
  • N - Cisterna chyli 
  • O - Superficial lymphatic vessels 
  • P - Thoracic duct 
  • Q - Posterior mediastinal nodes 
  • R - Anterior axillary nodes 
  • S - Left subclavian vein
  • T - Thoracic duct 
  • U - Superficial cervical nodes 
  • V - Left internal jugular vein
  • W - Area draining to thoracic duct (grey)
  • X - Blood blow 
  • Y - Venule 
  • Z - Lymphatic capillaries 
  • Ai - Blood flow 
  • Bi - Arteriole 
  • Ci - Tissue cells
  • Di - Capillary bed 
  • Ei - Lymph flow 
  • Fi - Lymphatic valve
  • Gi - Lymph node
  • Hi - Vein
  • Ii - Efferent lymphatic vessel to vein or to secondary node 
  • Ji - To thoracic duct 
  • Ki - Artery 
  • Li - Lymphatic valve 
  • Mi - Traveculae 
  • Ni - Follicle
  • Oi - Afferent lymphatic vessel to node
  • Pi - Interstitial fluid

 

  • Light - Superficial 
  • Dark - Deep

 

36

What are the main functions of lymph nodes? 

  • Phagocytic cells act as filters for particulate matter and microorganisms
  • Antigen presentation to the immune system 

 

37

Describe the structure of a lymph node

  • Fibrous capsule from which trabecular extend towards the centre 
  • Node itself made of three components 

 

38

What is the result of the trabecular extending from the fibrous capsule of the lymph nodes? 

Forms a framework 

39

What components is the node made of? 

  • Lymphatic sinuses 
  • Blood vessels 
  • Parenchyma 

 

40

What does the parenchyma of the lymph nodes consist of? 

  • Cortex
  • Paracortex
  • Medulla 

 

41

Label this diagram

  • A - Medulla 
  • B - Paracortex
  • C - Cortex
  • D - Afferent lymphatic vessels 
  • E - Lymphoid follice 
  • F - Postcapillary high endothelial venule 
  • G - Marginal sinus 
  • H - Medually sinus 
  • I - Efferent lymphatic vessel 
  • J - Artery 
  • K - Vein 

42

What does the cortex of the lymph nodes consist of? 

Mainly B cells 

43

What does the paracortex of the lymph nodes consist of? 

Mainly T cells 

44

How to B cells enter the lymph nodes? 

Via post-capillary venules that have high endothelium, High Endothelial Venules (HEV)

45

What happens once B cells have entered the lymph nodes? 

They pass to follicles 

46

What happens to unstimulated B cells in the lymph nodes? 

They pas out rapidly from the node to return to circulation with the lymph 

47

What happens to B cells activated by antigenic stimulation? 

They proliferate and remain in the node 

48

What are activated B cells within the lymphoid follicles known as? 

Follicle centre cells 

49

What kind of nucleus do follicle centre cells have? 

Either cleaved nuclei or more open/several nuclei 

50

What are follicle centre cells called when they have cleaved nuclei? 

Centrocytes 

51

What are follicle centre cells called when they have more open/several nuclei? 

Centroblasts 

52

What is the pale staining central area of a secondary follicle known as? 

A geminal centre 

53

What is a germinal centre surrounded by? 

A mantle zone of small, naive B cells and a few T cells 

54

What happens to stimulated B cells in the cortex? 

They proliferate and undergo somatic hypermutation and are selected for high affinity antibodies to the antigen displaced by follicular dendritic cells 

55

What happens once stimulated B cells have been selected for high affinity antibodies? 

They take up the antigen, process it, and present it to T cells 

56

What happens once antigens have been presented to T cells? 

T cells then further promote the development of B celsl by releasing cytokines 

57

What cytokines to T cells release on presentation of an antigen by B cells? 

IL-4

58

What do B cells become when T cells have released IL-4 

Centrocytes, then centroblasts 

59

What happens to centroblasts once they have been produced? 

They leave the follicle and pass to the paracortex and medullary sinuses 

60

What do centroblasts become when they have passed to the paracortex and medullary sinuses? 

Immunoblasts 

61

What do immunoblasts give rise to? 

Plasma cells or memory B cells 

62

What does the paracortex of the lymph node contain? 

  • Lymphocytes 
  • Accessory cells 
  • Supporting cells 

 

63

What is the paracortex of the lymph node the predominant site for? 

T-Lymphocytes in the lymph node 

64

What is the medulla of the lymph node rich in? 

Macrophages

65

What does the medulla of the lypmh nodes comprise? 

  • Large blood vessels 
  • Medullary cords
  • Medullary sinuses 

 

66

What are the medullary cords rich in? 

Plasma cells 

67

What happens to the antibodies produced in the medullary cords? 

They pass out of the node via the efferent lymphatics 

68

What is the cellular composition of the lymphoid follicles? 

B cells 

69

What is the cellular composition of the paracortex? 

T cells 

70

What is the cellular composition of the medulla? 

Plasma cells 

71

What do HEVs allow?

Lymphocytes (B cells) to pass into lymph nodes from the circulation 

72

What % of lymphocytes enter the node in the lymph? 

10%

73

How do the majority of lymphocytes the lymph node? 

From the blood via HEVs 

74

Describe the passage of lympho through lymph nodes 

Afferent lymphatics -> Marginal sinus -> Cortical sinus -> Medually sinus -> Efferent lymphatics

75

How is the particulate matter in the lymph removed? 

By macrophages

76

What do APCs facilitate? 

The specific immune response 

77

Where is the spleen located? 

In the upper left quadrant, or hypochondrium, of the abdomen 

78

Describe the appearance of the spleen

  • Ovoid
  • Usually purplish
  • Pulpy mass 
  • About the size and shape of a fist 

 

79

What is the spleen considered to be? 

The most vulnerable abdominal organ, as it is relatively delicate 

80

What is the arterial supply of the spleen from? 

The splenic artery 

81

What is the splenic artery? 

The largest branch of the coeliac trunk 

82

What course does the splenic artery follow? 

A tortuous course posterior to the omental bursa, anterior to the left kidney, and along the superior border of the pancreas 

83

What does the coeliac trunk give rise to? 

Splenic artery 

84

What happens between the layers of the splenorenal ligament? 

The splenic artery divides into five or more branches that enter the hilum 

85

What do the branches of the splenic artery between the layers of the splenorenal ligament do? 

Supply different vascular semgments of the spleen

86

Label this diagram

  • A - Aorta 
  • B - Celiac artery 
  • C - Common hepatic artery 
  • D - Dorsal pancreatic artery 
  • E - Greater pancreatic artery 
  • F - Splenic artery 

 

87

What does the venous drainage of the spleen flow via? 

The splenic vein

88

What is the splenic vein formed by? 

Several tributaries that emerge from the hilum 

89

What is the splenic vein joined by? 

The inferior mesenteric vein 

90

Where does the splenic vein run for most of its course? 

Posterior to the body and tail of the pancreas 

91

What does the splenic vein unite with? 

The Superior Mesenteric Vein 

92

Where does the splenic vein unite with the superior mesenteric vein? 

Posterior to the neck of the pancreas 

93

What is formed when the splenic vein units with the superior mesenteric vein? 

It forms the hepatic portal vein 

94

Label this diagram

  •  A - Superior pancreaticoduodenal vein
  • B - Hepatic portal vein 
  • C - Short gastric vein
  • D - Pancreatic veins 
  • E - Splenic vein
  • F - Inferior mesenteric vein
  • G - Inferior pancreatiocoduodenal vein
  • H - Superior mesenteric vein 

95

What is red pulp? 

A 'sponge-like' blood filtration system 

A complex system of blood vessels 

96

What does red pulp do?

Removes old or damaged RBCs from the circulation 

97

What does white pulp contain? 

  • T cells 
  • B cells 
  • Accessory cells 

 

98

What does white pulp have many similarities with? 

Lymph node structure 

99

What is the purpose of white pulp? 

To mount an immunological response to antigens within the blood

100

What may removal of the spleen lead to? 

Enhanced susceptibility to infection, especially by polysaccharide encapsulated bacteria, in particular Streptococcus pneumoniae, Haemophillus influenzae, and meningococcus

 

 

101

Where is Gut Associated Lymphoid Tissue (GALT) found? 

  • Tonsils/adenoids (Waldeyer's ring)
  • Peyer's patches
  • Lymphoid aggregates in the appendix and large intestine
  • Lymphoid tissue accumulating with age in the stomach
  • Diffusely distributed lymphoid cells and plasma cells in the gut lamina propria 

 

102

What do large aggregates of GALT have?

APCs, and distinct B cell follicles and T cell areas 

103

What are Peyer's Patches? 

Quite large aggregates of lymphoid tissue found in the small intestine 

104

What do Peyer's Patches do? 

Generate an immune response within the mucosa 

105

What do some epithelial cells in the 'dome' overlying Peyer's Patches have?

Complex microfolds (M cells) 

106

Are HEVs present in Peyer's Patches? 

No

107

What happens in Peyer's Patches? 

  • B cell precursors and memory cells in Peyer's Patches are stimulated by antigens 
  • Cells pass to the mesenteric lymph nodes, where response is amplified 
  • Activated lymphocytes pass into the blood via the thoracic duct 
  • Activated cells home in to the gut to carry out final effector functions

 

108

What can happen to lymphocytes and some mononuclear phagocytes? 

They can recirculate between lymphoid and non-lymphoid tissues

109

What does the recirculation between lymphoid and non-lymphoid tissues help in? 

Allowing lymphocytes to be exposed to the antigens that they recognise 

110

What is the advantage of allowing lymphocytes to be exposed to the antigens that they recognise? 

It is valuable in the distribution of effector cells of the immune response to sites where they are needed 

111

How may naive lymphocytes move? 

From the primary to secondary lymphoid tissue via the blood 

112

How may activated lymphocytes move? 

From the spleen, lymph nodes, and MALT into the blood, and from there to other lymphoid and non-lymphoid tissues 

113

How may APCs such as macrophages and dendritic cells move? 

May carry antigen back to lymphoid tissues from the periphery 

114

What do the complex patterns of recirculation depend on? 

  • The state of activation of the lymphocytes
  • The adhesion molecules expressed by endothelial cells
  • The presence of chemotactic molecules that selectively attract particular populations of lymphocytes or macrophages