The Lymphatic System Flashcards
(97 cards)
1
Q
Where do HSC arise from?
A
Foetal liver / post-natal bone marrow
2
Q
What organ is associated with B cell maturation?
A
Bone marrow
3
Q
What organ is associated with T cell maturation?
A
Thymus
4
Q
What is the central (primary) lymphoid system composed of?
A
Bone marrow + thymus
5
Q
What is the peripheral (secondary) lymphoid tissue composed of?
A
- Lymph nodes.
- Spleen.
- Tonsils (Waldeyer’s ring).
- Epithelio-lymphoid tissues.
- Bone marrow.
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).
7
Q
What is splenomegaly?
A
Enlarged spleen
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
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
10
Q
Describe the appearance of a lymph node.
A
Small, oval bodies, measuring up to 2.5cm.
11
Q
Where are lymph nodes located?
A
Along lymphatic vessels
12
Q
What are lymphatic vessels?
A
Blind-ending vascular channels that collect fluid from tissues and return to the blood stream
13
Q
What type of movement do lymphatic vessels depend on?
A
Passive movement of fluid
14
Q
What ensures the direction of flow through lymphatic vessels?
A
Valves
15
Q
What drains lymph through the capsule of the lymph node?
A
Afferent channels – through the capsule in to the peripheral sinus
16
Q
What leaves from the hilum of the lymph node?
A
Effect channel - allows lymph to leave the node
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.
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
19
Q
Where do arterial and venous vessels serving the node enter/exit?
A
At the hilum
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
21
Q
Where would lymph oedema be seen in a patient post-axillary clearance from breast cancer?
A
Arm
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
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
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
25
How does the lymphatic system prevent lymphedema?
By returning lymph to the circulation
26
The lymphoid system is an important DEFENCE system
T
27
How does the lymphoid system act as a defence system?
* Houses cells of the innate immune system
* Traffic of APC’s links innate and adaptive immune responses
* Seat of the adaptive immune response
28
What are the 3 types of lymphocyte found in lymph nodes?
* B cells
* T cells
* NK cells
29
What are B cells associated with?
Follicles and germinal centres.
30
Where are plasma cells mainly found?
In the medulla
31
What are the 2 types of T cell?
* T helper cells
| * T cytotoxic cells.
32
What other cells are found in lymph nodes (except lymphocytes)?
* Mononuclear phagocytes (macrophages), antigen presenting cells, dendritic cells.
* Endothelial cells.
33
What is CD20 a marker of?
B cells
34
What is CD3 a marker of?
T cells
35
If a person has an enlarged lymph node, think . . .
Is this evidence of underlying pathology?
36
What are the 2 main groups of causes of lymph node enlargement?
* Reactive process
| * Neoplastic disorder
37
What are the 4 main causes of lymphadenopathy?
* Local inflammation
* Systemic inflammation
* Malignancy
* Others
38
List causes of local inflammation which may cause lymphadenopathy.
* Infection
* Vaccination
* Trauma
39
List causes of systemic inflammation which may cause lymphadenopathy.
* Infection
* Autoimmune
* CT disorder
40
List malignancies which may cause lymphadenopathy.
* Haem- lymphoma, leukaemia
| * Mets
41
List diseases under the heading of 'others' which can cause lymphadenopathy.
* Sarcoidosis
| * Castlemans Disease
42
List lymph nodes in the body which can be palpated.
* Cervical
* Axillary
* Inguinal
43
What major internal lymph node groups can be viewed radiologically?
* Mediastinum
| * Para-aortic
44
When examining a patient with regional lymphadenopathy, examine the territory that drains to that group of nodes
T
45
In cases of superficial infection may see red lines extending from an inflamed lesion, what is this known as?
Lymphangitis
46
When may B cells predominate?
* Autoimmune conditions
| * Infections
47
When may a phagocytic response predominate?
The draining of a tumour site
48
When may T cells predominate?
* Viral infections
| * Drugs e.g. phenytoin.
49
What may superficial lymphadenopathy be the first sign of?
An underlying malignancy
50
What does generalised lymphadenopathy imply?
Either a system inflammatory process, or widespread malignancy.
51
If widespread malignancy is the cause, what are high on the differential diagnosis?
Lymphoma/leukaemia.
52
What should always be done before a biopsy?
FBC
53
The spleen is a _________ lymphoid organ
Secondary
54
Where is the spleen located?
High in the left upper quadrant of the abdomen.
55
What are the normal dimensions and weight of the spleen?
12x7x3cm.
| Up to 150-200g.
56
The spleen is usually not palpable unless predominantly enlarged
T
57
What are the 2 key aspects of the surface of the spleen?
1. Diaphragmatic surface.
| 2. Visceral surface – left kidney, gastric fundus, tail of pancreas, splenic flexure of colon.
58
The spleen is a very ________ organ
Vascular
59
What is the visceral surface of the spleen in contact with?
Left kidney, gastric fundus, tail of pancreas, splenic flexure of colon.
60
Describe the blood supply to the spleen.
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
What is the blood supply TO the spleen?
Splenic artery (a branch of the coeliac axis)
62
What is the blood supply AWAY from the spleen?
Splenic vein (forms the portal vein with the SMV)
63
Rupture of the spleen is a .....
Surgical emergency
64
When might the spleen rupture?
* Trauma
| * If spleen is diseased and more prone to trauma
65
The spleen is an encapsulated organ
T
66
What does the parenchymal of the spleen include?
Red + white pulp
67
What does red pulp contain?
Sinusoids and cords
68
Sinusoids are f__________
Fenestrated
69
What lines sinusoids?
Endothelial cells
70
What are sinusoids supported by?
Hoops of reticulin
71
What do cords of the red pulp of the spleen contain?
Macrophages and some fibroblasts and cells in transit (RBC, WBC, PC and some CD8+ T cells).
72
What is the function of the spleen?
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
How does white pulp of the spleen look on histology?
Purple
74
How does red pulp of the spleen look on histology?
Pink
75
What is the white pulp of the sinusoids of the spleen composed of?
The peri-arteriolar lymphoid sheath (PALS) – CD4+ lymphoid cells
76
What is white pulp expanded by?
Lymphoid follicles
77
As the white pulp of the sinusoids of the spleen is expanded by lymphoid follicles, what does this mean clinically?
Show reactive changes as in lymph nodes
78
How do antigens reach white pulp?
Via the blood
79
What happens once antigens reach the white pulp of the sinusoids of the spleen?
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
What symptoms might a patient with an enlarged spleen experience?
* Dragging sensation in LUQ.
* Discomfort with eating (early satiety)
* Pain if infarction.
81
Why might someone with an enlarged spleen experience early satiety as a symptom?
Their enlarged spleen is pressing on their stomach
82
HYPERSPLENISM is a triad of ...
1. Splenomegaly.
2. Fall in one or more cellular components of blood.
3. Correction of cytopenias by splenectomy.
83
OUTLINE CAUSES OF SPLENOMEGALY
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
Conditions which cause hypersplenism are associated with what?
Splenomegaly
85
What is the KEY diagnostic feature of hypersplenism?
Whether cytopenias resolve after splenectomy
86
What is the only way to diagnose hypersplenism?
To take out the spleen and see if the cytopenia resolves
87
In cases of bone marrow failure, what may we have to try to balance?
The productivity of the spleen with its role in excessive removal of circulating blood cells
88
What is the most common cause of HYPOSPLENISM?
Splenectomy (need for immunisation).
89
List causes (other than splenectomy) which cause hyposplenism.
* Coeliac disease.
* Sickle cell disease.
* Sarcoidosis.
* Iatrogenic – non-surgical.
90
What do the features of hyposplenism mainly arise due to?
Reduced red pulp function
91
What is a KEY feature, seen on bloods, of someone with hyposplenism?
Howell-Jolly bodies. (nuclear remnants, occur when there is no functioning spleen)
92
What may reduced red pulp function be associated with?
Some immune deficiency
93
When might someone definitely have immune deficiency if they have hyposplenism?
If they had their spleen removed in childhood
94
What type of tissues are the lymph nodes and spleen?
Secondary lymphoid tissue
95
LN’s respond to antigens filtered in lymph fluid
T
96
Spleen responds to antigens in blood.
T
97
Name 3 functions of the spleen.
* Phagocytosis.
* Haematopoiesis: normal in foetus, site of extramedullary haematopoiesis in marrow disease.
* Erythrocyte storage.
