Spleen is an important organ that is considered as a part of the lymphatic system. This organ is present in almost all vertebrates, including humans and dogs, and it performs several significant functions in their body. The human spleen is located in the upper left part of the abdomen, just below the diaphragm and behind the stomach. It is a small organ, not larger than the size of a fist. The average human spleen is about 12 cm in length, 7cm in height, 4cm thick and it weighs 150 gm approximately. The human spleen is a soft organ, which is dark purple in color. The tissues of this organ can be classified into two types, white pulp and red pulp, which are responsible for performing some specific functions. About 10% of population also has a small spleen in addition to the usual one. This extra spleen is called accessory spleen and poses no harm.
Like any other organ in the body, spleen is also susceptible to various diseases and infections. These conditions can cause enlargement of this organ, which is referred as splenomegaly. This disorder can seriously impede the myriad functions of spleen in the body. In this article, we have taken an overview of spleen function in humans, as well as medical conditions that impair spleen function.
What Does the Human Spleen Do?
As has been mentioned already, human spleen is an important constituent of the lymphatic system. It is concerned with producing lymphocytes, which is a type of white blood cells. So, spleen is an integral part of the human immune system, as the lymphocytes are responsible for producing antibodies to fight against the foreign invaders. Antibodies are mainly associated with the destruction of the bacteria, virus or any other microorganisms or germs, that can cause several diseases. This immune function of the spleen is the subject matter of the white pulp of the organ.
The red pulp of the spleen on the other hand, is concerned with looking after the filtration activities, i.e. removing the old or damaged red blood cells from the body. It is also responsible for acting as a reservoir of blood to be supplied in time of emergencies like hemorrhagic shock or excess loss of blood due to cuts or injury. By acting as a filter, spleen recognizes as well as removes the old, damaged and malformed red blood cells from the body. The old red blood cells are then broken down by the macrophages, which are a type of phagocytes. Macrophages not only engulf and digest the red blood cells, but other invading microorganisms and debris as well.
Another important feature of spleen function is that while filtering the blood, i.e. while destroying the old red blood cells, it preserves iron and some important components from them. Iron is stored in the spleen as bilirubin and ferritin. Iron preserved in this way is then transported to the bone marrow, which is the main site for synthesizing hemoglobin. Hemoglobin is a type of protein consisting of heme and globin and it transports oxygen from the lungs to all tissues and organs of our body. Apart from these functions, spleen also stores monocytes, which is a type of leukocytes that help engulfing and digesting bacteria and other harmful microorganisms.
Diseases that can Disrupt Spleen Functions
Several diseases can cause enlargement of the spleen and thereby disrupt its functions. Enlargement of the spleen or splenomegaly is the main health problem associated with the organ. Conditions like infection, malaria, anemia, systematic lupus, cancer like lymphoma and leukemia and liver diseases such as cirrhosis can cause an enlargement of the organ, which results from the excess trapping of blood cells and platelets. This in turn, can raise the risk of other diseases and infections. Sometimes, a significant increase in the size of the spleen may result in rupture, which necessitates immediate medical attention. Such a condition may require surgery to remove a part or the entire spleen. Another medical condition that hampers the function of spleen is sickle cell anemia. In this disease, abnormal red blood cells obstruct the flow of blood to the spleen, thereby resulting in its failure.
These abnormal conditions can be diagnosed with a CT scan, MRI scan, ultrasound or a bone marrow biopsy. Enlarged spleen can be felt by a physician during physical examination. A general assessment of symptoms is done in order to ascertain the cause of spleen dysfunction.
An important fact about spleen is that, though it performs several important functions, it is not a vital organ, i.e. humans can survive without a spleen. In the case of surgical removal of the entire organ, most of the spleen functions are taken up by liver and other organs of the body. However, if only a part of the spleen is removed, the organ may regenerate itself. Though we can survive without spleen, absence of it can raise the risk of infections. Besides this, it can also affect the amount of circulating blood cells and platelets. Therefore, spleen enlargement should not be neglected and should be immediately attended in order to detect the underlying causes.