Spleen Part 1
- Its weight is 150 grams and measuring 12×7×3 cms.
- It has thin capsules which consists of connective tissues.
- There are no smooth muscles in the capsules. So spleen has no contractile function.
- There are grey specks areas called splenic or malpighian follicles. This is called white pulp.
- While mononuclear phagocytic system and sinusoid is called Red pulp.
- There are two circuits of circulation :
- Open circuit is slow. There are thin sinusoids called cords of Billroth. These are part of Red pulp. These splenic cords consists of net work of macrophagic cells and this functional and physical filter.
- Closed circuit is fast. It has afferent artery converting into vein.
Functions of spleen
- Filtration : 1/120 RBC dies every day. This death takes place in 50% in the spleen.
- Culling : This destruction and removal of abnormal RBCs and antibody coated cells.
- Pitting : This is removal of inclusion like siderotic granules, Heinz bodies, and Howell Jowel bodies.
- Phagocytosis : Other particulate material like bacteria, viruses, carcinoma cells, macromolecule of Gaucher’s and Niemann Pick disease are removed by phagocytosis.
- Major secondary organ : In immune system it’s role is both in humoral and cellular immunity.
- Source of lymphoid cells : There may be extramedullary hematopoiesis, called myeloid metaplasia.
- Storage site : It stores platelets 30 to 40%. In case of enlargement of spleen, this may reach to 80 to 90%.
- There are 30 to 40 ml of RBCs and it increases in case of splenomegaly.