Lymphatic System: Characteristics, Parts And Functions
We all know some curious fact about the circulatory system. For example, you will at least know that a human being has about 5 liters of blood flowing through his arteries, veins and capillaries, or that the heart pumps all of the body’s blood in just over a minute. This fluid red that life gives us is also one of the students’ first contact with biology, which is why it is more than present in general culture.
Red blood cells or red blood cells flow in the blood, responsible for transporting oxygen to each and every one of the tissues in our body, with the help of hemoglobin. White blood cells or leukocytes also circulate through this fluid, cell bodies responsible for signaling and eliminating endogenous and exogenous pathogens, either specifically or nonspecifically. Blood is essential to understanding the immune system, but if we only talk about it, we are leaving something very important out.
Indeed, in this article we will talk about the great forgotten aspect of human circulation: the lymphatic system The human body produces approximately 3 liters of lymph per day, which is incorporated into the blood and circulates through small capillaries. If you want to know everything about this enigmatic fluid system, continue reading.
According to the National Cancer Institute (NIH), the lymphatic system can be defined as the set of tissues and organs that produce, store and transport white blood cells, which are responsible for fighting infections and other deleterious events for the body (exposure to chemicals, presence of allergic substances or cancer cells, for example). Conceiving life today without the action of immune mechanisms would be impossible.
The lymphatic system transports fluid (lymph, more specifically) throughout the body through a network of thin tubules. For this reason, It is the second circulatory system of the body, and some authors consider it as an accessory part of the blood system since it ends up emptying into the venous system, at the junction between the subclavian vein and the left jugular vein.
This system includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels, in addition to the circulating lymph itself. We dissect each of these parts in the following lines.
1. Bone marrow
The bone marrow is a spongy tissue found inside some bones in the body (and it has nothing to do with the spinal cord). In colloquial language it is known as marrow. All circulating blood cells (red blood cells, lymphocytes, macrophages, neutrophils and many more) are derived from a pluripotent hematopoietic stem cell, which is found in the bone marrow.
In an adult human, this type of tissue represents 4% of its total mass and approximately 500,000 million red blood cells are produced in it per day. It is an effective and tireless machinery when it comes to cell production.
2. Spleen
The spleen is an organ that is located on the left in the body, just below the rib cage Its main function is immunological, since as blood passes through it, it filters antigens and in its germinal centers specific antibodies are formed for them, known as immunoglobulins. It is also a place of essential relevance for the elimination of old circulating red blood cells (splenic hemocatheresis), which allows us to renew this essential cell type.
Because of its link to immune activity, infections, certain types of cancer or liver diseases can cause an enlarged spleen, a condition known as splenomegaly. This condition often has no symptoms, but when it does it usually manifests itself as swelling in the left upper abdominal area.
3. Timo
The thymus is the organ of the lymphatic system where T lymphocytes grow and multiply It is located in the thorax, behind the sternum, in front of the heart. Hematopoietic progenitor cells (remember that they are formed in the bone marrow) come here to develop, acquiring the name thymocytes.
T lymphocytes are essential for the understanding of adaptive immunity, as they directly attack foreign bodies specifically and produce cytokines, biological substances that help activate other cellular components of the immune system.
4. Lymph nodes
Lymph nodes are small structures that contain lymphocytes, which are essential for fighting diseases and responding to them in the short and long term They are formations that are located in the path of the lymphatic vessels, forming chains or clusters, through which the lymph is filtered. Throughout the body there are hundreds of lymph nodes connected to each other: to give you an idea, in the armpit alone there are between 20 and 40 of these unique structures.
Additionally, the lymph nodes They differentiate between peripheral and internal The former are easily palpable, as they are located below the skin, and their inflammation can indicate various pathologies. In many of these cases, lymphadenopathy or plain adenopathy occurs, which corresponds to inflammation of the lymph nodes due to infectious processes, cancerous tumors, HIV and tuberculosis, among others. Increased lymph node volume is a clear clinical sign of disease.
5. Lymphatic vessels
lymphatic vessels They are located throughout the body, and are larger than blood capillaries Almost all lymphatic vessels contain specialized valves, which allow the lymph to go in only one direction and clotting does not occur.
The lymph
How can we leave in the pipeline the liquid that gives its name to the entire system and is the reason for being of all the previously named structures? Lymph is a practically transparent liquid that is produced from excess fluid that leaves the blood capillaries into the intercellular space This unique liquid contains white blood cells, proteins, fats and salts and, unlike the circulatory system with the heart, it does not have a pumping device that transports it throughout the body.
Lymph circulates thanks to the body’s own muscular contractions, since its purpose is to return to the circulatory system. In addition to containing immune cells and nutrients, it is also responsible for transporting foreign substances, damaged cells and cancerous cell bodies that may have entered the tissue fluids.
We have painted a general picture of the functioning and usefulness of the lymphatic system in the previous lines, but it never hurts to make a general summary to finish. We’ll see now a list of the most important functions of the lymphatic system:
Thus, the lymphatic system takes care of many more tasks than one might initially think: It transports nutrients, serves as a fluid recycling mechanism and, most important of all, is one of the essential bases for the immune response
For this reason, lymphadenopathy (inflammation of the lymph nodes) is an essential diagnostic element for many pathologies. For example, breast cancer can be detected by axillary lymphadenopathy: when the tumor is present in a breast, metastatic cells travel through the lymphatic system to the nearest lymph node (in this case in the armpit), causing it to swell and enlarge. . This is a very powerful diagnostic tool before the tumor spreads to the rest of the body.
Summary
The functions of the lymphatic system can be defined in two basic pillars: transport and immunity Here leukocytes, the most important cell bodies for understanding the human immune system, both innate and acquired, are synthesized and transported.
Although you can live without one of the lymphoid organs such as the spleen, its absence can drastically reduce the ability to respond to exogenous infections and other harmful internal processes. Without a doubt, the importance of the lymphatic system as a whole has been more than justified in these lines.
