The spleen‘s main functions are to remove old blood cells and fight off infection. Red blood cells have an average life span of 120 days. Most are created from the marrow of long bones, such as the femur. When they’re old, it’s the spleen’s job to identify them, filter them out and then break them down.
The smaller particles are then sent back into the bloodstream, and either recycled or excreted from other parts of the body. This takes place in the ‘red pulp’, which are bloodvessel-rich areas of the spleen that make up about three-quarters of Its structure.
The remainder is called ‘white pulp’, which are areas filled with different types of immune cell (such as lymphocytes). They filter out and destroy foreign pathogens, which have invaded the body and are circulating in the blood. The white pulp breaks them down into smaller, harmless particles.
The spleen is surrounded by a thin, fragile capsule and so is prone to injury. It sits beneath the lower ribs on the left-hand side of your body, which affords it some protection, but car crashes, major sports impacts and knife wounds can all rupture the organ. In the most serious cases, blood loss can endanger the person’s life, and in these situations it needs to be removed by a surgeon. Since this reduces the body’s ability to fight infections, some people will need to take antibiotics to boost their immunity for the rest of their lives.
The immune system
Although the red blood that flows through our bodies gets all the glory, the transparent lymphatic fluid is equally important. It has its own body-wide network which follows blood vessel flow closely and allows for the transport of digested fats, immune cells and more…
Spleen – One of the master co-ordinatois that staves off infections and filters old red blood cells. It contains numerous lymphocytes that recognise and destroy invading pathogens present in the blood as it flows through the spleen.
Thymus – A small organ that sits just above the heart and behind the sternum. It teaches T-lymphocytes to identify and destroy specific foreign bodies. Its development is directly related to hormones in the body so it’s only present until puberty ends; adults don’t need one.
Tonsils – These are masses of lymphoid tissue at the back of the throat and can be seen when the mouth is wide open. They form the first line of defence against inhaled foreign pathogens, although they can become infected themselves, causing tonsillitis.
Adenoids – These are part of the tonsillar system that are only present in children up until the age of five; in adults they have disappeared. They add an extra layer of defence in our earlyyears.
Bone marrow – This forms the central, flexible part of our long bones (eg femur). Bone marrow is essential as it produces our key circulating cells, including red blood cells, white blood cells and platelets. The white blood cells mature into different types (eg lymphocytes and neutrophils), which serve as the basis of the human immune system.
Lymph nodes – These are small (about lcm/ 0.4m) spherical nodes that are packed with macrophages and lymphocytes to defend against foreign agents. These are often linked in chains and are prevalent around the head, neck, axillae (armpits) and groin.