Definition of spleen
The spleen is a organ small organ, typically located on the left side of the body, behind the rib cage and the stomach. It is the largest organ of the lymphatic system system of the body, which is responsible for promoting immune function, filtering the blood and control blood volume.
The lymphatic system is the system of lymph ducts and lymph nodes that lie beneath the lymphatic system. skin. They are a channel through which white blood cells can travel out of the bloodstream and are also a receptacle for bacteria, dead cells, debris and extra fluid that can accumulate in the blood.
It performs several useful functions for the body, including the production of antibodies, killing bacteria, removing old red blood cells, breaking down red blood cell waste products, recycling of iron for use in new red blood cells and the retention of a reserve of red blood cells. and immune cells that the body can use in case of emergencies.
The spleen produces antibodies in a type of tissue called “white pulp”. Its tissue called “red pulp” contains a reservoir of immune cells that fight infection and promote tissue healing, which it can release as needed.
The image below shows where it is found in the body, along with the arrangement of its “red pulp” and “white pulp”:

Although the spleen is useful to the body, it is not essential for survival. Some of its functions can be taken over by other organs if it is removed; other functions of the spleen are useful in an emergency, but are not necessary for survival in most circumstances.
The spleen may need to be removed if it becomes injured or infected. In these cases, it may pose more of a risk than a benefit to the rest of the body, and doctors may choose to perform surgery to remove it.
The spleen can also be damaged by sickle cell disease, which can block its blood flow. This is one reason why people with sickle cell disease should receive additional immunisations.
People without a spleen usually live a normal, healthy life, although they are advised to get regular immunisations to protect against infections.
Interestingly, about 10% of people have an “accessory spleen”, a small extra spleen! This causes no problems or symptoms, and most people only discover they have an accessory spleen if they require imaging scans of their body for another reason.
Spleen function
The spleen performs numerous useful functions for the body, including:
- Manufacture of antibodies
- Storing emergency stocks of red blood cells that can be released in case of blood loss.
- Store emergency reserves of white blood cells that can be released to fight infection and promote healing.
- Break down waste products from dead cells.
- Recycle useful components, such as iron, for use in future red blood cells
It is easy to see how the spleen helps us survive illness and injury, and helps us recover useful nutrients.
In the modern era, spleens are not necessary for survival. With full protections such as vaccinations and antibiotics and the ability to take iron supplements if necessary, people without spleens are simply advised to take a little more care in vaccinating themselves and avoiding disease.
The spleen is most often removed due to injury, such as injuries sustained during car accidents or from playing sports. An injured or ruptured spleen causes massive blood loss that can quickly become life-threatening.
There is some research suggesting that the spleen may have a little-known role in preventing cardiovascular disease, as one study found that people who had their spleen removed were more likely to die from cardiovascular disease than a control group.
For this reason, some scientists advocate better injury prevention, such as protective body armour for athletes, to reduce the chance of spleen injuries that may result in the need for spleen removal.
Location of the spleen
In most people, the spleen is located under the left side of the rib cage, next to the stomach. It cannot usually be felt or detected, as it is only the size of a fist and is hidden behind the stomach.
Its location means that the spleen is fairly well protected, but it can still be injured by blows to the chest and side, such as those sometimes suffered in sports or car accidents.
A ruptured spleen can be very dangerous to the rest of the body. This is because the spleen processes a large blood supply, so a ruptured spleen can cause rapid and massive blood loss. For that reason, spleens are sometimes removed if they are injured and there is concern that they may rupture.
Occasionally, doctors may feel the spleen if it is abnormally swollen, as in the case of mononucleosis, blood cancers and other conditions. If someone is suspected of having these conditions, doctors may palpate the spleen if it is abnormally swollen. abdomen for signs of an enlarged spleen.
Structure of the spleen
The spleen consists of two different types of tissues, red pulp and white pulp. These tissues are enclosed within a tissue membrane. The external surface of the spleen can be divided into two parts: the diaphragmatic surface and the visceral surface. Here we will discuss more about each of these important features.
Diaphragmatic surface
The diaphragmatic surface of the spleen is the surface that faces the diaphragm. This is an upward facing surface that curves outwards, pressing against the diaphragm.
The diaphragm, a muscle The strong muscle located below the lungs and stomach, which allows us to breathe, is located between the spleen and the lung.
Visceral surface
The visceral surface of the spleen faces downwards towards the organs of the “viscera”, “intestine”. It is divided by a ridge into two regions: the renal region and the gastric region.
The “gastric” or stomach region is the “anterior” or front surface of the spleen. It faces forward and curves inward, like a soup spoon. This allows it to curve around the stomach, which inserts into the spleen. The lower part of the gastric region touches the tail of the pancreas.
The “renal” or kidney region faces the centre of the body and downwards. It comes into contact with the front part of the left kidney, and sometimes with the gland adrenal gland left.
Red pulp
The red pulp of the spleen serves the circulatory system by filtering the blood and acting as a recycling station for red blood cells and a storage point for other important blood components. It constitutes the bulk of the tissue in most healthy spleens.
The red pulp is made up of connective tissue called “Billroth’s cords”. These first filter the blood, removing pathogens and red blood cells that have reached the end of their useful life. It then uses immune cells called macrophages to break down the useless or harmful components of these cells, while saving useful components such as iron for use in future red blood cells.
The red pulp also stores white blood cells (another type of white blood cell), special cells called “splenic cells” that store, digest and transport red blood cells and platelets.
Sometimes platelet deficiency can occur because the spleen stores too many platelets and does not release enough of them into the blood.
White Pulp
The white pulp of the spleen is the tissue that performs the immune functions of the spleen. It consists of a layer of different tissues and nodules, each of which performs different functions for the immune system:
- The periarteriolar lymphoid sheaths (PALS) serve as a reservoir for white blood cells called T lymphocytes. Some scientists have described this reservoir of white blood cells as similar to having a standing army, ready to mobilise to protect the body in case of attack.
- Lymph follicles contain a type of blood cell called B lymphocytes, which divide and reproduce within the follicles. This tissue also produces antibody molecules that help the immune system recognise and fight disease. Other tissues in the body also perform these functions, so they will not stop if the spleen is removed; but the spleen gives the immune system extra strength by producing these cells and antibodies.
- The marginal zone contains a unique type of cell called “antigen-presenting cells”. Antigens are molecules found on bacteria or other organisms. viruses that antibodies and white blood cells recognise. The term literally comes from “anti-” for “antibody” y “gen“for “start”.
Antigen-presenting cells serve the immune system by eating invading pathogens and then presenting molecules from the pathogens on the surface of their cells. This can “teach” and stimulate other immune cells to respond to new pathogens.