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

Where is the thymus gland found?

A

In the thorax in the anterior mediastinum

2
Q

Where does the thymus gland lie?

A

Posterior to the sternum, and anterior to the pericardium

3
Q

What happens to the thymus gland as we age?

A

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

4
Q

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

A

Reduciton in the functioning mass of the gland

5
Q

When does the thymus gland cease to function?

A

It doesn’t- it continues to function throughout life

6
Q

Label this diagram

A
  • 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
Q

What is the thymus gland arranged into?

A

Outer cortex and inner cortex

8
Q

How does the outer cortex differ from the inner medulla?

A

It is more cellular

9
Q

What does the inner medulla of the thymus gland havw?

A

Hassall’s corpuscles

10
Q

What are Hassall’s corpuscles?

A

Aggregated thymic epithelial cells

11
Q

What is the cellular composition of the thymus gland?

A
  • Lymphoid cells
  • Macrophages
  • Other supporting cells
  • Epithelial cells
12
Q

Describe the epithelial cells in the thymus gland

A

Have different appearances in different loations within the gland

13
Q

What do the epithelial cells of the thymus gland form?

A

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

14
Q

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

A

They are aggregated into Hassall’s corpuscles

15
Q

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

A

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
Q

What is the lymphoid system?

A

An ‘overflow system’

17
Q

What does the lymphoid system provide?

A

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

18
Q

What are lymphatic plexuses?

A

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

19
Q

What are the lymphatic vessels?

A

A nearly body-wide network of vessels

20
Q

Describe the structure of lymphatic vessels

A

Thin walled, abundant lymphatic valves

21
Q

Where do lymphatic capillaries and vessels occur?

A

Almost everywhere blood capillaries are found

22
Q

Where are lymphatic capillaries are vessels not found?

A
  • Teeth
  • Bone
  • Bone marrow
  • CNS
23
Q

What are lymph nodes?

A

Small masses of lymphatic tissue

24
Q

Where are lymph nodes located?

A

Along the course of lymphatic vessels

25
Q

What happens at lymph nodes?

A

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

26
Q

What are lymphoid organs?

A

Parts of the body that produce lymphocytes

27
Q

Give 5 lymphoid organs

A
  • Thymus
  • Red bone marrow
  • Spleen
  • Tonsils
  • GALT
28
Q

What is lymph?

A

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

29
Q

Describe the appearance of lymph

A

Usually clear, watery, and slightly yellow

30
Q

What do superficial lymph nodes drain into?

A

Deep lymph nodes

31
Q

What do deep lymph nodes do?

A

Join to form lymphatic trunks

32
Q

What do lymphatic trunks do?

A

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

33
Q

What does the right lymphatic duct drain into?

A

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

34
Q

Where does the thoracic duct drain?

A

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

35
Q

Label this diagram

A
  • 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
Q

What are the main functions of lymph nodes?

A
  • Phagocytic cells act as filters for particulate matter and microorganisms
  • Antigen presentation to the immune system
37
Q

Describe the structure of a lymph node

A
  • Fibrous capsule from which trabecular extend towards the centre
  • Node itself made of three components
38
Q

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

A

Forms a framework

39
Q

What components is the node made of?

A
  • Lymphatic sinuses
  • Blood vessels
  • Parenchyma
40
Q

What does the parenchyma of the lymph nodes consist of?

A
  • Cortex
  • Paracortex
  • Medulla
41
Q

Label this diagram

A
  • 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
Q

What does the cortex of the lymph nodes consist of?

A

Mainly B cells

43
Q

What does the paracortex of the lymph nodes consist of?

A

Mainly T cells

44
Q

How to B cells enter the lymph nodes?

A

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

45
Q

What happens once B cells have entered the lymph nodes?

A

They pass to follicles

46
Q

What happens to unstimulated B cells in the lymph nodes?

A

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

47
Q

What happens to B cells activated by antigenic stimulation?

A

They proliferate and remain in the node

48
Q

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

A

Follicle centre cells

49
Q

What kind of nucleus do follicle centre cells have?

A

Either cleaved nuclei or more open/several nuclei

50
Q

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

A

Centrocytes

51
Q

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

A

Centroblasts

52
Q

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

A

A geminal centre

53
Q

What is a germinal centre surrounded by?

A

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

54
Q

What happens to stimulated B cells in the cortex?

A

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

55
Q

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

A

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

56
Q

What happens once antigens have been presented to T cells?

A

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

57
Q

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

A

IL-4

58
Q

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

A

Centrocytes, then centroblasts

59
Q

What happens to centroblasts once they have been produced?

A

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

60
Q

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

A

Immunoblasts

61
Q

What do immunoblasts give rise to?

A

Plasma cells or memory B cells

62
Q

What does the paracortex of the lymph node contain?

A
  • Lymphocytes
  • Accessory cells
  • Supporting cells
63
Q

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

A

T-Lymphocytes in the lymph node

64
Q

What is the medulla of the lymph node rich in?

A

Macrophages

65
Q

What does the medulla of the lypmh nodes comprise?

A
  • Large blood vessels
  • Medullary cords
  • Medullary sinuses
66
Q

What are the medullary cords rich in?

A

Plasma cells

67
Q

What happens to the antibodies produced in the medullary cords?

A

They pass out of the node via the efferent lymphatics

68
Q

What is the cellular composition of the lymphoid follicles?

A

B cells

69
Q

What is the cellular composition of the paracortex?

A

T cells

70
Q

What is the cellular composition of the medulla?

A

Plasma cells

71
Q

What do HEVs allow?

A

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

72
Q

What % of lymphocytes enter the node in the lymph?

A

10%

73
Q

How do the majority of lymphocytes the lymph node?

A

From the blood via HEVs

74
Q

Describe the passage of lympho through lymph nodes

A

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

75
Q

How is the particulate matter in the lymph removed?

A

By macrophages

76
Q

What do APCs facilitate?

A

The specific immune response

77
Q

Where is the spleen located?

A

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

78
Q

Describe the appearance of the spleen

A
  • Ovoid
  • Usually purplish
  • Pulpy mass
  • About the size and shape of a fist
79
Q

What is the spleen considered to be?

A

The most vulnerable abdominal organ, as it is relatively delicate

80
Q

What is the arterial supply of the spleen from?

A

The splenic artery

81
Q

What is the splenic artery?

A

The largest branch of the coeliac trunk

82
Q

What course does the splenic artery follow?

A

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

83
Q

What does the coeliac trunk give rise to?

A

Splenic artery

84
Q

What happens between the layers of the splenorenal ligament?

A

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

85
Q

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

A

Supply different vascular semgments of the spleen

86
Q

Label this diagram

A
  • A - Aorta
  • B - Celiac artery
  • C - Common hepatic artery
  • D - Dorsal pancreatic artery
  • E - Greater pancreatic artery
  • F - Splenic artery
87
Q

What does the venous drainage of the spleen flow via?

A

The splenic vein

88
Q

What is the splenic vein formed by?

A

Several tributaries that emerge from the hilum

89
Q

What is the splenic vein joined by?

A

The inferior mesenteric vein

90
Q

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

A

Posterior to the body and tail of the pancreas

91
Q

What does the splenic vein unite with?

A

The Superior Mesenteric Vein

92
Q

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

A

Posterior to the neck of the pancreas

93
Q

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

A

It forms the hepatic portal vein

94
Q

Label this diagram

A
  • 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
Q

What is red pulp?

A

A ‘sponge-like’ blood filtration system

A complex system of blood vessels

96
Q

What does red pulp do?

A

Removes old or damaged RBCs from the circulation

97
Q

What does white pulp contain?

A
  • T cells
  • B cells
  • Accessory cells
98
Q

What does white pulp have many similarities with?

A

Lymph node structure

99
Q

What is the purpose of white pulp?

A

To mount an immunological response to antigens within the blood

100
Q

What may removal of the spleen lead to?

A

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

101
Q

Where is Gut Associated Lymphoid Tissue (GALT) found?

A
  • 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
Q

What do large aggregates of GALT have?

A

APCs, and distinct B cell follicles and T cell areas

103
Q

What are Peyer’s Patches?

A

Quite large aggregates of lymphoid tissue found in the small intestine

104
Q

What do Peyer’s Patches do?

A

Generate an immune response within the mucosa

105
Q

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

A

Complex microfolds (M cells)

106
Q

Are HEVs present in Peyer’s Patches?

A

No

107
Q

What happens in Peyer’s Patches?

A
  • 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
Q

What can happen to lymphocytes and some mononuclear phagocytes?

A

They can recirculate between lymphoid and non-lymphoid tissues

109
Q

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

A

Allowing lymphocytes to be exposed to the antigens that they recognise

110
Q

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

A

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

111
Q

How may naive lymphocytes move?

A

From the primary to secondary lymphoid tissue via the blood

112
Q

How may activated lymphocytes move?

A

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

113
Q

How may APCs such as macrophages and dendritic cells move?

A

May carry antigen back to lymphoid tissues from the periphery

114
Q

What do the complex patterns of recirculation depend on?

A
  • 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