the spleen Flashcards
what are the main three structures of the spleen?
capsule , red pulp and white pulp
what does the red pulp consist of ?
consists of venous sinuses and is surrounded by cellular cords , has a role in immunity as it contains macrophages and granulocytes
what does the white pulp consist of ?
mainly lymphoid cells , primary follicles and secondary follicles
they have t cells surrounding arterioles (PALS)
what type of organ is the spleen ?
reticuloendothelial organ
what are the functions of the spleen?
filter function
pooling and storage function
hematopoetic function
role in immunity
explain the filter function of the spleen
it has a pitting and a culling function:
the pitting function includes the removal of intra-erythrocytic inclusions from circulating RBCs ( removal of heinz bodies )
the culling function includes the removal of aging or abnormal RBCs
explain the pooling and storage function
reticulocytes stay in the spleen for 1-2 days for maturation before release into the circulation
what is the role of the spleen in hematopoesis ?
spleen is the main source of RBCs in the 1st 5 months of fetal life
where does extra medullary hematopoesis occur?
spleen , liver
what is the role of the spleen in immunity ?
when blood circulates through the spleen (white pulp), it causes exposure of antigens to dendritic cells leading to antibody production and cell mediated immune response
what type of bacteria do the spleen protect against
encapsulated bacteria
immune complications with asplenic patients
more susceptible to infection by encapsulated bacteria
they have delayed IgM or low IgM
indications after splenectomy?
patients should be vaccinated to avoid overwhelming post splenectomy infections, should be vaccinated against streptococcus pneumoniae, menegitidits and influenza
what are the causes of splenomegaly
reactive causes congestive causes storage diseases systemic diseases haematological diseases primary splenic tumors tropical splenomegaly
reactive causes of splenomegaly
inflammations and infections such as bacterial endocarditis, typhoid and infectious mononucleosis oe could be chronic infections such as TB, visceral leishmaniasis
congestive causes of splenomegaly
congestive heart failure
portal hypertension
thrombosis of the portal or splenic vein
storage diseases causing splenomegaly
gaucher disease ( mainly in children)
Neiman pick disease
histocytosis X
systemic diseases causing splenomegaly
sarcoidosis
amyloidosis
collagen diseases
haematological cause of splenomegaly
thalassemia major or intermedia
chronic haemolytic anemia
myelofibrosis
marrow infiltration
primary splenic tumors
tumors or cysts
tropical splenomegaly
due to malaria
what are the clinical features of tropical splenomegaly;Malaria
huge splenomegaly hepatomegaly lymphadenopathy sever anemia moderate thrombocytopenia high malaria titre and serum IGM
what is hypersplenism ?
an overreactive spleen , this is a clinical syndrome which does not imply a specific mechanism
why is there a decrease in one or more of cell lines in hypersplenism ?
due to premature release of cells as a way to get rid of all the pooling causing anemia and cytopenia
when can hyposplenism happen?
after a splenectomy
may be due to sickle cell anemia
may be due to splenic artery thrombosis
what are the blood findings after splenectomy ?
the white blood cell and platelete counts typically increase
what blood findings indicate functional asplenia ?
Howell jolly bodies and target cells
what are Howell jolly bodies ?
the Howell body represent the residual of a red cell nucleus that hasn’t been removed by the spleen ,
what does the presence of Howell bodies indicate ?
hypo functional spleen or absent spleen
