S like spleen

S as in Spleen

The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.

The lymphatic system is made up of a network of lymphatic vessels.  These vessels carry lymph — a clear, watery fluid containing protein molecules, salts, glucose, urea, and other substances — throughout the body.

The spleen is located in the upper left part of the abdomen under the ribcage.  It works as part of the lymphatic system to protect the body, clearing worn-out red blood cells and other foreign bodies from the bloodstream to help fight off infection.

One of the lymphatic system's major jobs is to collect extra lymph fluid from body tissues and return it to the blood.  This process is important because water, proteins, and other substances are continuously leaking out of tiny blood capillaries into the surrounding body tissues.  If the lymphatic system didn't drain the excess fluid from the tissues, the lymph fluid would build up in the body's tissues and they would swell.

The lymphatic system also helps defend the body against germs like viruses, bacteria, and fungi that can cause illnesses.  Those germs are filtered out in the lymph nodes, which are small masses of tissue located along the network of lymph vessels.  The nodes house lymphocytes, a type of white blood cell.  Some of those lymphocytes make antibodies, special proteins that fight off germs and stop infections from spreading by trapping disease-causing germs and destroying them.

The spleen also helps the body fight infection. The spleen contains lymphocytes and another kind of white blood cell called macrophages, which engulf and destroy bacteria, dead tissue, and foreign matter and remove them from the blood passing through the spleen.

Lymph nodes are round or kidney shaped.  They can be up to 1 inch in diameter.  Most of the lymph nodes are found in clusters in the neck, armpit, and groin area.  Nodes are also located along the lymphatic pathways in the chest, abdomen, and pelvis, where they filter the blood.  Inside the lymph nodes, lymphocytes called T-cells and B-cells help the body fight infection.  Lymphatic tissue is also scattered throughout the body in different major organs and in and around the gastrointestinal tract.

The spleen helps control the amount of blood and blood cells that circulate through the body and helps destroy damaged cells.

Carrying Away Waste

Lymph fluid drains into tiny vessels called lymph capillaries.  The fluid is then pushed along through the capillaries when a person breathes or the muscles contract.  The lymph capillaries are very thin.  They have many tiny openings that let gases, water, and nutrients pass through to the surrounding cells, nourishing them and taking away waste products.  When lymph fluid passes through in this way it is called interstitial fluid.

Lymph vessels collect the interstitial fluid and then return it to the bloodstream by emptying it into large veins in the upper chest, near the neck..

An enlarged spleen is not always a sign of a problem.  When a spleen becomes enlarged, though, it often means it has been doing its job but has become overactive.  For example, sometimes the spleen is overactive in removing and destroying blood cells.  This is called hypersplenism.  It can happen for many reasons, including problems with too many platelets and other disorders of the blood.

Causes of an Enlarged Spleen

Splenomegaly (enlarged spleen).  In someone who is healthy, the spleen is usually small enough that it can't be felt when you press on the abdomen.  But certain diseases can cause the spleen to swell to several times its normal size.  Most commonly, this is due to a viral infection, such as mononucleosis.  But in some cases, more serious diseases such as cancer can cause the spleen to expand.