Lymphatics Flashcards
what are the two types of components of the lymphoid system?
Central (Primary)
Peripheral (Secondary) lymphoid tissues
what are the Central (Primary) lymphoid tissues?
o Bone marrow
o Thymus
what are the Peripheral (Secondary) lymphoid tissues?
o Lymph nodes o Spleen o Tonsils (Waldeyer’s ring) o Epithelio-lymphoid tissues o Bone marrow
precursor lymphoid cells that mature in the thymus become…
T cells
precursor lymphoid cells that mature in the bone marrow become…
B cells
what is the function of the lymphoid system?
• Filtration of circulatory fluids
• Location for cells of the immune system
(lymphoid and accessory)
what is the function of the lymphatic system?
Return lymph to the circulation
- fluid homeostasis, prevents oedema
what does the lymphatic system allow?
o Cell traffic
o Cell trapping
o Interaction with of cells and “molecules” with cells of the immune system – protective function
where are lymph nodes located?
Located along the course of lymphatic vessels
what are the structural features of lymphatic vessels?
o blind-ending vascular channels that collect fluid from tissues and return to blood stream
o passive movement of fluid
o valves ensure direction of flow
what is the flow of lymph drainage into lymphnodes?
Afferent channels - capsule - peripheral sinus - subcapsular sinus - hilus - efferent lymphatic
where do the efferent lymphatic vessels drain to?
Drains to:
- cisterna chyli / thoracic duct
- L jugular, subclavian or bronchomediastinal trunks
- R jugular, subclavian or bronchomediastinal trunks
And then to venous system at junction of L or R subclavian and jugular veins
what is the role of lymphnode groups?
drain particular territories
what is the histology of lymphnodes?
- Follicles separated by interfollicular tissues (home to T cells)
- B cells get activated in pale zone = germinal centre
what immune cells are found in lymph nodes?
B cells
T cells
NK cells
Also Mononuclear phagocytes, APCs and dendritic cells.
B cells are largely associated with what structure in the lymphnode?
- Associated with follicles and germinal centres
- Intrafollicular
- Plasma cells – mainly in the medulla
what are the different types of lymphnode enlargement?
- Lymphadenopathy
- Localised, more wide-spread or generalised
- Peripheral or Central (internal)
what are the causes of lymphadenopathy?
o Local inflammation - Infection, vaccination, dermatopathy
o Systemic inflammation - Infection, Autoimmune / CT disorders
o Malignancy - Haematological, Metastatic
o Others - e.g. Sarcoidosis, Castlemans Disease; IgG4 related disease
what is the normal size and weight of the spleen?
up to 150-200g and 12x7x3cm
what are the two key aspects of the spleen?
- Diaphragmatic surface
* Visceral surface - Left Kidney, gastric fundus, tail of pancreas, splenic flexure of colon.
what is the blood supply of the spleen?
Supplied by splenic artery (branch of coeliac axis) and drained by splenic vein (with SMV forms portal vein
what is the structure of the spleen?
– An encapsulated organ.
– Parenchyma includes red pulp and white pulp
what does the red pulp of the spleen contain?
sinusoids and cords.
what does the white pulp of the spleen contain?
– comprises the peri-arteriolar lymphoid sheath (PALS).
– This is expanded by lymphoid follicles
what are the features of splenic sinusoids?
- fenestrated
- lined by endothelial cells
- supported by hoops of reticulin.
what are the features of splenic cords?
contain macrophages and some fibroblasts and cells in transit (RBC, WBC, PC and some CD8+ T cells)
what is the role of splenic red pulp?
acts as a filter for the blood
• Detect, retain and eliminate unwanted, foreign or damaged material
• Facilitate immune responses to blood borne antigens
what is the role of splenic white pulp?
APCs in the white pulp present antigen to immune reactive cells
what are the clinical features of splenomegaly?
Dragging sensation in LUQ
Discomfort with eating
Pain if infarction
what is the triad of clinical features of hypersplenism?
splenomegaly, fall in one or more cellular components of blood, correction of cytopenias by splenectomy
what are the infective causes of splenomegaly?
Wide range: EBV, Malaria, TB, Typhoid, Brucellosis, Leishmaniasis, Trypanosomiasis,
what is a type of splenic atrophy?
hyposplenism
what are the causes of hyposplenism?
splenectomy
• Coeliac disease, Sickle cell disease, Sarcoidosis, Iatrogenic – non-surgical
what are the clinical features of hyposplenism?
Howell-Jolly bodies, other red cell abnormalities (hypernucleated), immune deficiency
what are the congestive causes of splenomegaly?
Portal (Hepatic cirrhosis, portal/splenic vein thrombosis, cardiac failure)
what are the haematological causes of splenomegaly?
Lymphoma/leukaemia, haemolytic anaemia, ITP, Myeloproliferative disorders
what are the inflammatory causes of splenomegaly?
Rheumatoid arthritis, SLE
what are the storage disease causes of splenomegaly?
Gaucher’s, Niemann-Pick disease
what are the miscellaneous causes of splenomegaly?
Amyloid, Tumours (primary and metastatic), cysts
