The Lymphatic System Flashcards

1
Q

Where do HSC arise from?

A

Foetal liver / post-natal bone marrow

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2
Q

What organ is associated with B cell maturation?

A

Bone marrow

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3
Q

What organ is associated with T cell maturation?

A

Thymus

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4
Q

What is the central (primary) lymphoid system composed of?

A

Bone marrow + thymus

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5
Q

What is the peripheral (secondary) lymphoid tissue composed of?

A
  • Lymph nodes.
  • Spleen.
  • Tonsils (Waldeyer’s ring).
  • Epithelio-lymphoid tissues.
  • Bone marrow.
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6
Q

In clinic, what do you have to decide about enlarged lymph nodes?

A
  • Lymphadenopathy.
  • Localised, more widespread or generalised.
  • Peripheral or central (internal).
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7
Q

What is splenomegaly?

A

Enlarged spleen

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8
Q

What is the function of the lymphatic system?

A
  • Important function in fluid homeostasis

* Prevent excessive accumulation of fluid in the tissues – oedema

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9
Q

What does the lymphoid system permit?

A
  • Cell traffic
  • Cell trapping
  • Interaction with of cells and “molecules” with cells of the immune system – protective function
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10
Q

Describe the appearance of a lymph node.

A

Small, oval bodies, measuring up to 2.5cm.

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11
Q

Where are lymph nodes located?

A

Along lymphatic vessels

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12
Q

What are lymphatic vessels?

A

Blind-ending vascular channels that collect fluid from tissues and return to the blood stream

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13
Q

What type of movement do lymphatic vessels depend on?

A

Passive movement of fluid

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14
Q

What ensures the direction of flow through lymphatic vessels?

A

Valves

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15
Q

What drains lymph through the capsule of the lymph node?

A

Afferent channels – through the capsule in to the peripheral sinus

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16
Q

What leaves from the hilum of the lymph node?

A

Effect channel - allows lymph to leave the node

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17
Q

What do the efferent vessels of the lymph node drain to?

A
  • cisterna chyli/thoracic duct.
  • L jugular, subclavian or bronchomediastinal trunks.
  • R jugular, subclavian or bronchomediastinal trunks.
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18
Q

After leaving the lymph node, where does lymph drain to?

A

The venous system at the junction of the L or R subclavian and jugular veins

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19
Q

Where do arterial and venous vessels serving the node enter/exit?

A

At the hilum

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20
Q

What happens to lymph, in the lymph node, before it is returned to the circulation?

A

It is filtered within the node parenchyma

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21
Q

Where would lymph oedema be seen in a patient post-axillary clearance from breast cancer?

A

Arm

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22
Q

Why does axillary surgery for breast cancer cause lymphoedema?

A

Disrupts the ability of the lymphatics to return fluid back to the circulation

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23
Q

What is chylous ascites?

A

Main trunk draining lymph back is obstructed or damaged

Accumulation of lipid rich lymph in the peritoneal cavity due to distruption secondary to trauma or obstruction

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24
Q

What is the 2 main functions of the lymphatic system?

A
  • To return lymph to the circulation

* To filter lymph before returning it to the circulation

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25
Q

How does the lymphatic system prevent lymphedema?

A

By returning lymph to the circulation

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26
Q

The lymphoid system is an important DEFENCE system

A

T

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27
Q

How does the lymphoid system act as a defence system?

A
  • Houses cells of the innate immune system
  • Traffic of APC’s links innate and adaptive immune responses
  • Seat of the adaptive immune response
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28
Q

What are the 3 types of lymphocyte found in lymph nodes?

A
  • B cells
  • T cells
  • NK cells
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29
Q

What are B cells associated with?

A

Follicles and germinal centres.

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30
Q

Where are plasma cells mainly found?

A

In the medulla

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31
Q

What are the 2 types of T cell?

A
  • T helper cells

* T cytotoxic cells.

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32
Q

What other cells are found in lymph nodes (except lymphocytes)?

A
  • Mononuclear phagocytes (macrophages), antigen presenting cells, dendritic cells.
  • Endothelial cells.
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33
Q

What is CD20 a marker of?

A

B cells

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34
Q

What is CD3 a marker of?

A

T cells

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35
Q

If a person has an enlarged lymph node, think . . .

A

Is this evidence of underlying pathology?

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36
Q

What are the 2 main groups of causes of lymph node enlargement?

A
  • Reactive process

* Neoplastic disorder

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37
Q

What are the 4 main causes of lymphadenopathy?

A
  • Local inflammation
  • Systemic inflammation
  • Malignancy
  • Others
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38
Q

List causes of local inflammation which may cause lymphadenopathy.

A
  • Infection
  • Vaccination
  • Trauma
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39
Q

List causes of systemic inflammation which may cause lymphadenopathy.

A
  • Infection
  • Autoimmune
  • CT disorder
40
Q

List malignancies which may cause lymphadenopathy.

A
  • Haem- lymphoma, leukaemia

* Mets

41
Q

List diseases under the heading of ‘others’ which can cause lymphadenopathy.

A
  • Sarcoidosis

* Castlemans Disease

42
Q

List lymph nodes in the body which can be palpated.

A
  • Cervical
  • Axillary
  • Inguinal
43
Q

What major internal lymph node groups can be viewed radiologically?

A
  • Mediastinum

* Para-aortic

44
Q

When examining a patient with regional lymphadenopathy, examine the territory that drains to that group of nodes

A

T

45
Q

In cases of superficial infection may see red lines extending from an inflamed lesion, what is this known as?

A

Lymphangitis

46
Q

When may B cells predominate?

A
  • Autoimmune conditions

* Infections

47
Q

When may a phagocytic response predominate?

A

The draining of a tumour site

48
Q

When may T cells predominate?

A
  • Viral infections

* Drugs e.g. phenytoin.

49
Q

What may superficial lymphadenopathy be the first sign of?

A

An underlying malignancy

50
Q

What does generalised lymphadenopathy imply?

A

Either a system inflammatory process, or widespread malignancy.

51
Q

If widespread malignancy is the cause, what are high on the differential diagnosis?

A

Lymphoma/leukaemia.

52
Q

What should always be done before a biopsy?

A

FBC

53
Q

The spleen is a _________ lymphoid organ

A

Secondary

54
Q

Where is the spleen located?

A

High in the left upper quadrant of the abdomen.

55
Q

What are the normal dimensions and weight of the spleen?

A

12x7x3cm.

Up to 150-200g.

56
Q

The spleen is usually not palpable unless predominantly enlarged

A

T

57
Q

What are the 2 key aspects of the surface of the spleen?

A
  1. Diaphragmatic surface.

2. Visceral surface – left kidney, gastric fundus, tail of pancreas, splenic flexure of colon.

58
Q

The spleen is a very ________ organ

A

Vascular

59
Q

What is the visceral surface of the spleen in contact with?

A

Left kidney, gastric fundus, tail of pancreas, splenic flexure of colon.

60
Q

Describe the blood supply to the spleen.

A

Supplied by the splenic artery – a branch of the coeliac axis.
Drained by the splenic vein, which forms the portal vein with the SMV.

61
Q

What is the blood supply TO the spleen?

A

Splenic artery (a branch of the coeliac axis)

62
Q

What is the blood supply AWAY from the spleen?

A

Splenic vein (forms the portal vein with the SMV)

63
Q

Rupture of the spleen is a …..

A

Surgical emergency

64
Q

When might the spleen rupture?

A
  • Trauma

* If spleen is diseased and more prone to trauma

65
Q

The spleen is an encapsulated organ

A

T

66
Q

What does the parenchymal of the spleen include?

A

Red + white pulp

67
Q

What does red pulp contain?

A

Sinusoids and cords

68
Q

Sinusoids are f__________

A

Fenestrated

69
Q

What lines sinusoids?

A

Endothelial cells

70
Q

What are sinusoids supported by?

A

Hoops of reticulin

71
Q

What do cords of the red pulp of the spleen contain?

A

Macrophages and some fibroblasts and cells in transit (RBC, WBC, PC and some CD8+ T cells).

72
Q

What is the function of the spleen?

A

Basically carried out the same function for blood as lymph nodes do for lymph fluid i.e. acts as a filter for the blood

  • detect, retain and eliminate unwanted, foreign or damaged material.
  • facilitate immune responses to blood-borne antigens
73
Q

How does white pulp of the spleen look on histology?

A

Purple

74
Q

How does red pulp of the spleen look on histology?

A

Pink

75
Q

What is the white pulp of the sinusoids of the spleen composed of?

A

The peri-arteriolar lymphoid sheath (PALS) – CD4+ lymphoid cells

76
Q

What is white pulp expanded by?

A

Lymphoid follicles

77
Q

As the white pulp of the sinusoids of the spleen is expanded by lymphoid follicles, what does this mean clinically?

A

Show reactive changes as in lymph nodes

78
Q

How do antigens reach white pulp?

A

Via the blood

79
Q

What happens once antigens reach the white pulp of the sinusoids of the spleen?

A

APC’s in the white pulp present the antigen to immune reactive cells.

And when stimulated by the antigen, T and B cell responses may occur.

80
Q

What symptoms might a patient with an enlarged spleen experience?

A
  • Dragging sensation in LUQ.
  • Discomfort with eating (early satiety)
  • Pain if infarction.
81
Q

Why might someone with an enlarged spleen experience early satiety as a symptom?

A

Their enlarged spleen is pressing on their stomach

82
Q

HYPERSPLENISM is a triad of …

A
  1. Splenomegaly.
  2. Fall in one or more cellular components of blood.
  3. Correction of cytopenias by splenectomy.
83
Q

OUTLINE CAUSES OF SPLENOMEGALY

A

Infection

  • Wide range: EBV, Malaria, TB, Typhoid, Brucellosis, *Leishmaniasis, Trypanosomiasis,

Congestion

  • Portal (Hepatic cirrhosis, portal/splenic vein thrombosis, cardiac failure)

Haematological diseases

  • Lymphoma/leukaemia, haemolytic anaemia, ITP, Myeloproliferative disorders

Inflammatory conditions

  • Rheumatoid arthritis, SLE

Storage diseases

  • Gaucher’s, Niemann-Pick disease

Miscellaneous
* Amyloid, Tumours (primary and metastatic), cysts

(ICHISM – infection, congestion, haematological, inflammatory, storage diseases, miscellaneous)

84
Q

Conditions which cause hypersplenism are associated with what?

A

Splenomegaly

85
Q

What is the KEY diagnostic feature of hypersplenism?

A

Whether cytopenias resolve after splenectomy

86
Q

What is the only way to diagnose hypersplenism?

A

To take out the spleen and see if the cytopenia resolves

87
Q

In cases of bone marrow failure, what may we have to try to balance?

A

The productivity of the spleen with its role in excessive removal of circulating blood cells

88
Q

What is the most common cause of HYPOSPLENISM?

A

Splenectomy (need for immunisation).

89
Q

List causes (other than splenectomy) which cause hyposplenism.

A
  • Coeliac disease.
  • Sickle cell disease.
  • Sarcoidosis.
  • Iatrogenic – non-surgical.
90
Q

What do the features of hyposplenism mainly arise due to?

A

Reduced red pulp function

91
Q

What is a KEY feature, seen on bloods, of someone with hyposplenism?

A

Howell-Jolly bodies. (nuclear remnants, occur when there is no functioning spleen)

92
Q

What may reduced red pulp function be associated with?

A

Some immune deficiency

93
Q

When might someone definitely have immune deficiency if they have hyposplenism?

A

If they had their spleen removed in childhood

94
Q

What type of tissues are the lymph nodes and spleen?

A

Secondary lymphoid tissue

95
Q

LN’s respond to antigens filtered in lymph fluid

A

T

96
Q

Spleen responds to antigens in blood.

A

T

97
Q

Name 3 functions of the spleen.

A
  • Phagocytosis.
  • Haematopoiesis: normal in foetus, site of extramedullary haematopoiesis in marrow disease.
  • Erythrocyte storage.