Spleen is a flat oblong big gland made by lymphoid tissue. It is a gland without duct and in the left side of abdominal cavity in the left hypochondriac region inferior to diaphragm by touching to the fundus of liver, left kidney, tail of pancreas and splenic flexure of large intestine. Its shape and size is like a closed fist which is 12 centimeter long, 7 centimeter broad and 2.5 centimeter thick normally and its weight is about 200 grams. Its color is dark purple.
There are two edges anterior and posterior and there are two surfaces too. One surface is conves which is under the diaphragm. The second surface is concave which is in the contact of fundus of liver, left kidney, pancreas and splenic flexure. There is a hilum on the lower side of the concave surface and through which splenic artery, nerves and lymph vessels enter into the spleen and splenic vein come out from it.
The tissue formation of spleen is like the formation of lymphonodes which is covered by a capsule from all around whereby the spleen gets divided into several parts because of the trabeculae emerged inwardly. These divided parts are called lobules. There is a cellular substance in the functioning portion of medulla which is called splenic pulp. It is of two types-red and white. Red pulp is present in the whole spleen in sufficient quantity in which small parts of white pulp are scattered. White pulp is made of compact masses of lymphocytes around the small brainches of splenic artery. These masses, which are in the gaps, are called splenic nodules or malpighian corpuscles. There are venous sinusoids filled with blood inside the white pulp and there are monocytes and macrphages in it. The monocytes helps in building leucocytes and macrophages swallow to the red broken blood cells and dissolve them.
The branches of splenic artery put blood into the splenic pulp directly by reaching into the spleen. There is no capillary in the spleen whereby the blood comes into the contact of cells of spleen and gathers into the venous sinusoids. From here, the blood goes into the branches of splenic vein and splenic vein comes into the existence because of their meeting. This splenic vein meets with portal vein.
Functions of the spleen:
- Filtering blood and building macrophages cells-lymphocytes and monocytes are the major functions of the spleen.
- Macrophages cells present in sufficient number in the spleen help in removing damaged or erythrocytes cells and platelets and micro viruses and other debris. Macrophages remove the iron from the weak red cells of hemoglobin and return it back into the circulation for the production of red blood cells. The pigment named bilirubin originates because of breaking the hemoglobin which is circulated in the liver.
- Antigens present in the blood of spleen get developed in cells by making active to the lymphocytes and make antibodies.
- The spleen builds red blood cells in the embryo stage. Later on, it stores fresh red blood cells and platelets and relive them into the blood in need.
- Spleen does the work of blood reservoir.