The Human Spleen: Functions and Importance

The Human Spleen

Description

 The spleen is an organ system located in the upper far left part of the abdomen, to the left of the stomach. I chose to discuss this organ because it is often neglected as essential and I wanted to know how it impacts one’s health. This organ fluctuates in size and shape depending on the individual, but it’s normally fist-shaped, purple, and about 5 inches long, weighing around 6 ounces (Bailey, 2018, October 22). It is a soft, spongy organ that appears purple due to the quantity of blood vessels running through it. Since the spleen is shielded by the rib cage, you can’t feel it unless it’s abnormally enlarged. Although its location is near the digestive organs, the spleen is actually part of the lymphatic system, responsible for filtering toxins and waste out of the body as part of the larger immune system (Bailey, 2018, October 22). The spleen removes the body’s old and damaged red blood cells and stores white blood cells for the fighting of infections (Bailey, 2018, October 22).

Function of the Spleen

Filtering blood is the most important job of the spleen. As blood flows into the spleen, it damaged red blood cells are detected (Bailey, 2018, October 22). Blood flows through a web of channels in the spleen. Healthy cells flow straight through and the unhealthy are broken down by large white blood cells called macrophages. Once the red blood cells are broken down the spleen stores useful nutrients such as iron, and returns it to the bone marrow. This permits hemoglobin to produce. In humans, around 1 cup of blood is kept in the spleen, ready to be released if there is a significant loss of blood (Bailey, 2018, October 22). The spleen clears out old platelets from the blood and acts as a reservoir. As a fetus is developing, the spleen makes red blood cells, but after the fifth month of gestation, it stops (Bailey, 2018, October 22).

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The spleen also produces compounds to help the immune system called opsonins, which include properdin and tuftsin (HM, 2019). An opsonin is any molecule that improves phagocytosis by designing an antigen for an immune response, or marking dead cells for reprocessing (HM, 2019). Opsonins help the immune system in several ways. In a healthy individual, they mark dead and dying cells for clearance, trigger complement proteins, and target cells for annihilation by using natural killer cells (HM, 2019). Properdin is a protein present in the blood that aids in the how the body responds to certain kinds of infection (HM, 2019). Tuftsin is a peptide associated with the immune system function, and produced primarily in the spleen (HM, 2019).

Tissues within this Organ System

Two types of tissue directly control the organ’s function. The white pulp portion of the spleen produces B and T-lymphocytes (Bailey, 2018, October 22). T-lymphocytes (T-cells) are responsible for cell mediated immunity, which is an immune response that involves the initiation of certain immune cells to fight infection (Bailey, 2018, October 22). B-lymphocytes (B-cells) originate from bone marrow stem cells. B-cells create antibodies that are specific to an antigen (Bailey, 2018, October 22). The antibody binds to the antigen and labels it for destruction by other immune cells (Bailey, 2018, October 22). Both white and red pulp contains lymphocytes and immune cells called macrophages (Bailey, 2018, October 22). These cells remove antigens, dead cells, and debris by eating them. The lymphocytes can create protein antibodies that attack microbes that have invaded the body and could cause infection. The spleen’s red pulp controls blood-filtering functions. Red pulp consists of venous sinuses and splenic cords. Venous sinuses are vital cavities filled with blood, while splenic cords are connective tissues containing red blood cells and certain white blood cells including lymphocytes and macrophages (Bailey, 2018, October 22). The red pulp breaks down old or damaged red blood cells along with other waste from the blood, and then removes it from the body. Likewise, the spleen’s red pulp holds different types of white blood cells calls phagocytes, which consume foreign bodies such as bacteria and viruses (Bailey, 2018, October 22).

Human Body Systems Interconnected with the Spleen

The circulatory system rests on the normal functioning of the bone marrow and spleen (Lori, et al. 2017). They work synergistically in carrying out the majority of the blood-producing roles, while the other assists in cleaning the blood stream and replenishing cells after an injury or infection (Lori, et al. 2017). Without the cells delivered by these organs, the circulatory system would contain only lymphatic components, and the human body would not survive (Lori, et al. 2017).

In previous years, researchers focused their attention on finding the basis of the immune system’s innervation, revealing that spleen receives fibers from the nervous system (Lori, et al. 2017). Several experiments have been developed since then to develop our understanding of the splenic innervation. Research and science have described that sympathetic nervous system fibers innervate the spleen, and their synaptic endings are right alongside with immune cells (Lori, et al. 2017). Released neurotransmitters come in contact with lymphocytes, networking with their specific receptors and controlling immune cells responses. These properties portray the neuro-immune communication (Lori, et al. 2017). Once they are stimulated, the immune cells produce and discharge a variety of pro- or anti-inflammatory mediators, which offer an immune cell response (Lori, et al. 2017). The neuro-immune interaction provides an important connection between immune cells and the nearby fibers of the autonomic nervous system supplying the spleen. This current discovery has revealed that the nervous system controls immunological responses induced by hypertensive stimuli (Lori, et al. 2017). This implies that the same neuro-immune communication in this secondary lymphoid organ replenishes immune cells in tissue during metabolic disease (Lori, et al. 2017).

Complications

 This spleen is vulnerable to several diseases and injuries that may affect the organ’s function or require it to be surgically removed from the body. Liver diseases or blood cancers may enlarge a spleen, which can cause abdominal pain (Ruth, 2017). A ruptured spleen, or one that has been injured from a blow to the body, can cause internal bleeding and is usually a life-threatening emergency. Ruptured spleens may be repaired, but removing the organ is often the safest treatment (Ruth, 2017). People can live without a spleen, but they are more prone to infectious diseases. Other parts of your body, like your liver and lymph nodes, are able to jump in and take over many of your spleen’s functions (Ruth, 2017). The spleen play a large role in supporting the body by filtering blood to keep our immune system operating optimally, so having it removed will have a significant impact on our immune system. Specifically, the spleen helps fight bacteria that cause pneumonia and meningitis (Bronte & Pittet, 2013).

Diseases and Conditions that Affect the Spleen

Some diseases and conditions that can involve the spleen include: accessory spleen, ruptured spleen, splenomegaly, sickle cell disease, thrombocytopenia, splenic infarction and cancer of the spleen (Bronte & Pittet, 2013). Accessory spleen affects about fifteen percent of people, and is a condition where a second spleen is present. This supernumerary spleen is around 1 centimeter in diameter, and usually causes no health problems. It can however become twisted around its vascular pedicle and cause abdominal pain (Bronte & Pittet, 2013). A ruptured spleen occurs after an injury and sometime results in life-threatening internal bleeding. On occasion the spleen will burst at the time of the injury, while other times it will burst days later (Bronte & Pittet, 2013). Diseases like malaria and infectious mononucleosis are more likely to cause the spleen to rupture because they cause swelling and the protective capsule becomes thinner (Bronte & Pittet, 2013). Splenomegaly (enlarged spleen) is brought on my infectious diseases including bacterial infections, liver disease, mononucleosis and blood cancers (Bronte & Pittet, 2013). When this organ is especially overactive it can destroy too many red blood cells or platelets.

Sickle cell disease is an inherited form of anemia as a result of a dysfunctional type of hemoglobin (Ruth, 2017). Red blood cells are crescent shaped which causes a blockage in the flow of blood resulting in damage to the spleen, bond, gallstones, kidney damage and eye damage (Ruth, 2017). Thrombocytopenia is a disorder in which your blood has a lower than normal number of platelets (Bronte & Pittet, 2013). If the spleen becomes enlarged it can store too many platelets, taking away the rest of the body’s circulatory system. Without platelets available to help blood clot, the primary symptom of thrombocytopenia is bleeding. If cancer starts in the spleen, it is known as primary spleen cancer; if it spreads to the spleen from another site, it is called secondary. It is very rare that cancer initiates from the spleen (Bronte & Pittet, 2013). Some rare types of lymphoma can start there because the spleen contains lymphatic tissue and, though it’s unusual, some cancers can start in the spleen’s blood vessels. Lymphomas that start elsewhere in the body can also sometimes spread to the spleen, as can some other types of cancer. A Splenic infarction is when the blood supply to the spleen is reduced. This occurs if blood supply through the splenic artery is cut off by, for instance, a blood clot (Bronte & Pittet, 2013). When the spleen is in crisis mode due to these conditions, the blood stays in the spleen instead of flowing through it. When the spleen to becomes bigger and blood counts fall, it is knows as a splenic sequestration crisis (Ruth, 2017).

Conclusion

Although a person can survive without a spleen it is important to take preventative measures seriously in order to assure your organ will function properly in keeping you healthy. Many gastrointestinal disorders, such as poor appetite, dyspepsia, diarrhea and constipation result from a weak spleen organ system (Logic, 2019). The Spleen is also a very vulnerable organ that requires a lot of attention to keep it functioning well. If its health starts to become compromised, then symptoms of lethargy, bloating, acid reflux, irregular menstrual cycles, irritable bowel syndrome, and alternating bowel movements may start to arise (Logic, 2019). Some foods that tone up the spleen are: dates, grapes, pears, potatoes, cucumber, carrots, melon, cereals, liquorice, honey, cinnamon and aniseed (Logic, 2019).

References

• Bailey, Regina. (2018, October 22). How Does Your Spleen Work? Retrieved from https://www.thoughtco.com/spleen-anatomy-373248
• Bronte, V., & Pittet, M. J. (2013). The spleen in local and systemic regulation of immunity. Immunity, 39(5), 806-18.
• HM, M. (2019). Differential properties of organ-specific serum opsonins for liver and spleen macrophages. – PubMed – NCBI. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/2775783
• Logic, P. (2019). The Best Food for Healthy Spleen Function | Physio Logic in Brooklyn. Retrieved from https://physiologicnyc.com/best-food-healthy-spleen/
• Lori, A., Perrotta, M., Lembo, G., & Carnevale, D. (2017). The Spleen: A Hub Connecting Nervous and Immune Systems in Cardiovascular and Metabolic Diseases. International Journal of Molecular Sciences, 18(6), 1216. doi:10.3390/ijms18061216

• Ruth, M. (2017). Spleen. Salem Press Encyclopedia of Health. Retrieved from http://search.ebscohost.com/login.aspx?direct=true&AuthType=sso&db=ers&AN=125600465&site=eds-live&scope=site&authtype=sso&custid=ns083389