The Lymphoid System Flashcards
B cell maturation occurs where?
Bone marrow
T cell maturation occurs where?
Thymus
Primary lymphoid tissues?
Bone marrow
Thymus
Secondary lymphoid tissues?
Lymph nodes Spleen Tonsils Epithelio-lymphoid tissues Bone marrow
Where are lymph nodes located?
Along the course of lymphatic vessels
Efferent vessels leave the hilum of the lymph node and drain to where?
Cisterna chyli/ thoracic duct
Left/right jugular, subclavian or bronchomediastinal trunks
Where is the end of the route in lymph drainage?
Into venous system at junction of right/ left subclavian and jugular veins
Where is lymph filtered before returning to the blood stream?
Node parenchyma
What are the functions of the lymphatic system?
Return lymph to the circulation - fluid homeostasis and preventing accumulation -> oedema
Filter lymph
What is the cell population in lymph nodes?
Lymphocytes - B cells, T cells, NK cells Macrophages APCs Dendritic cells Endothelial cells
What is lymphadenopathy?
Enlarged lymph nodes
What causes lymphadenopathy?
Local inflammation - infection, vaccine, trauma
Systemic inflammation - infection, autoimmune, connective tissue disease
Malignancy - haematological, mets
Sarcoidosis
What are red lines called that extend from an inflamed region?
Lymphangitis
What is generalised lymphadenopathy suggestive of?
Systemic inflammatory process
Widespread malignancy
What artery supplies the spleen?
Splenic artery
What drains the spleen?
Splenic veins
What does the parenchyma of the spleen include?
Red pulp and white pulp
What does the red pulp in the spleen contain?
Sinusoids and cords
What does the White pulp contains?
Periartiolar lymphoid sheaths (PALS) - contains a lot of CD4+ cells (t helper cells)
What happens in the White pulp?
Antigen reaches White pulp by the blood
APCs in White pulp present antigen to immune reactive cells
When stimulated by antigen, T and B cell responses may occur
Features of splenic enlargement?
Dragging sensation in LUQ
Discomfort when eating
Pain if infarction
Hypersplenism
Triad of hypersplenism?
Splenomegaly
Fall on one or more cellular components of blood
Correction of cytopenias by splenomegaly
Causes of splenomegaly
Infection - EBV, malaria , TV , typhoid Congestion - portal Haematological diseases Inflammatory conditions - SLE, RA Storage disease Miscellaneous
Most common cause of hyposplenism?
Splenectomy
Causes of hyposplenism?
Splenectomy Coeliac Sickle cell Sarcoidosis Iatrogenic
A distinct feature of hyposplenism?
Howell-jolly bodies
