Hello healthy Steemians,
"As you all know what the heart does , it just pumps blood . Right ?"
" What about stomach ? Yes, it breaks down the food ! "
So what does the Spleen does ? Have you got any idea ? Look at the picture and go through the lines I wrote on it. It will surely make your emptiness on spleen away !
Fig.1 Anatomy of spleen with it's location on human body (credit)
Fig.2 Position of Spleen along with the lymphatic vessels and trunks (credit)
Spleen is purple colored organ located right just behind the stomach and under the lungs. It is about a size of a fist which is 5 inches wide and weighs about 150 gms. Normal and exact position of spleen lies at the left upper quadrant of the abdominal cavity near to the 9th rib to 12th rib. It lies just beneath to the diaphragm which is a sheet of a skeletal muscle.
Human spleen acts as a lymphatic organ i.e. acts as a defensive mechanism against certain conditions. Not only this, it acts as a storage for blood constituting of mainly Red Blood Cells (RBCs) and platelets for certain kind of emergency conditions. It's main work is filtering the blood.
Spleen is a bouncer for the blood. Cleans the dead cells, fight against foreign bodies and Stores blood for emergency .
Around the world, there are 10% of the population who has extra spleen called as "accessory spleen". This does not do any harm like other organs though. Spleen is not palpable mostly but can be palpable in the slender adult. Sizes like normal or small spleen cannot be diagnosed with infection or pathological process. Physical process cannot diagnose the condition of spleen. But, enlarger spleen can be the clue to varieties of infections.
Role in hematopoiesis and immunosurveillance
Spleen acts as a major organ for the removal of abnormal RBC or erythrocyte, micro-organisms and synthesizing antibodies or immunoglobulins G (IgG) . About IgG , it was discussed in the previous post which you can visit in here... Approximately 1/3rd of the platelets are stored in the spleen.
Spleen has two kind of tissue
- White pulp
- Red pulp
Fig.3 Microscopic Diagram of Spleen tissue (credit)
Spleen is surrounded by a capsule that extends a number of projections into the interior of speen forming compartments. White pulps are distributed throughout the spleen just like a tiny island formations acting like a giant lymph node. Just like a lymphatic nodule in lymph node , white pulp has splenic nodules where B-lymphocytes and T-lymphocytes are packed into. Whereas, red pulp is surrounded by blood and vascular sinuses. This pulp has numerous red cells , which is why it gives spleen a type of purplish color . Along with this, there is presence of lymphocytes and macrophages.
Red Blood cell's diameter is small as compared with the chylomicrons . This get easily permeable in the capillaries. RBC get squeezed into the pores and reaches the venous sinuses. When RBC gets too much in circulation, it becomes old after frequent use. It is easily breakable and more fragile. When these gets broken down, the resulting components gets attracted by the macrophages which are phagocyte in nature and reach the venous sinuses. Available macrophages also eat those bacterias and foreign particles which come into circulation as it flows into the venous channels. Spleen filters the blood as much pure the lymph node filters the lymph. Spleen damages the RBC generating and storing the component : Heme i.e. iron and globin i.e. amino acids and comes to the circulation when the body needs so.
Fig: Microscopic figure of spleen (credit) kctcs.edu
Normal adult spleen makes the body in homeostatsis by removing useless particles and potentially injurious substances and synthesizing immunoglobulins and properdin. By phagocytosis, it removes the foreign particles from the lymph when moving from interstitial space to the bloodstream. Phagocytes living in the blood vessels and spleen removes the particles reaching the blood. Monocytes becomes macrophages. Neutrophiles, monocytes and other macrophages makes a mononuclear phagocytic system (Reticuloendothelial system).
What does Splenomegaly refer to ?
Splenomegaly refers to the enlargement of spleen according to the weight and height. When length of spleen is 11 cm - 20 cm, it indicates splenomegaly and >20 cm refers to massive splenomegaly. As for the weight, when spleen weighs 400 g- 500g, it indicates splenomegaly and > 1000g it indicates massive splenomegaly. Cases of Splenomegaly can be viewed on Ultrasound, MRI, CT imaging. Splenomegaly can be due to the decreased or increased function depending upon the cause. It can be classified by three cause:
- Congestion
- Infiltration
- Proliferation
Fig: CT scan showing enlargement of spleen (credit)
During the conditions like portal hypertension or condition occlusing the splenic vein, pressure of the flowing blood to the arteries becomes more. Due to this, there is increased pressure in the splenic arteries where cascade of congestion appears. Due to this, there is hyperplasia i.e. increase size of cell and fibrosis occurs. Even during the cirrhosis condition, jaundice and varices like associated symptoms occurs with splenomegaly. In the other hand, pancreatitis has increased risk in developing thrombotic complication which result in splenomegaly.
In case of infiltration, as I have already said, spleen is highly vascular and acts as a central role of peripheral lymphatic organ. Both the malignant and non-malignant cells are invaded through it. Malignancies like metastatis tumor, leukemias, lymphomas are main cause for infiltration. Even I have discuss about the amylio bodies in the previous topic here... , such depository diseases are also the cause for infiltration. Spleen has become a primary site of extramedullary hematopoiesis in cases of myeloproliferative disorders.
This brings to the proliferation part. As I said, it filters blood rather than the lymph. This gives us a hint that it protect us from the blood borne pathogens or other blood foreign substances which makes the spleen hyperfunction. Acute infections due to bacterial ,viral, parasitical and fungal infections are more of the cause to the splenomegaly. Filtering the blood which are abnormal in structure can cause the hyperplasia of the spleen which include the cases of sickle cell disease, spherocytosis, hemoglobinopathies
Treatment for the abnormal spleen
Major treatment will be targeting the underlying cause for the splenomegaly , protecting from the complications. Patients are at high risk in developing ruptured spleen so, there should be increased attention to these people incase develope abnormal trauma. Treatment also includes avoidance of injury from mononucleosis, patients who spleen is taken out having leukemia.
Amazing fact: People can actually live without a spleen .
Splenectomy on the other hand has some high risk in developing infection against certain foreign particles. Organisms such as Streptococcus pneumoniae, Neisseria meningitidis , Haemophilus Influenza should be vaccinated to limit ta cause. These get more infected in the splenectomy patients if they are not vaccinated.
Conclusively, spleen is a lymphatic organ which is just opposite to the lymph node. It fillers the blood as lymph filters the lymph. Center for destruction of Red Blood Cells and foreign bodies . It even acts as a storage for the Blood and Platelets.
Reference :
Credits given along with the pictures . Further information :
(1)http://immunologyden.blogspot.com/2012/11/spleen.html
(2)http://knowledge-forlife.com/red-pulp-vs-white-pulp-spleen/
(3) Microscopic galllery of spleen
(4)https://www.livescience.com/44725-spleen.html
(5)https://www.medicinenet.com/enlarged_spleen/article.htm
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