O lymphatic system acts by ensuring the return of fluid contained in the surrounding tissues to the blood. This fluid, when it enters the lymphatic system, is called lymph and has a unidirectional circulation, always going towards the heart. The system is formed by lymphatic capillaries, lymphatic vessels, lymphatic ducts and lymph nodes.
When the fluid present in tissue spaces is not properly captured by the lymphatic system, we have the formation of edema. In elephantiasis, the formed edema causes a great deformity in the affected organ.
Read more:Cardiovascular system - responsible for ensuring blood circulation throughout the body
the lymphatic system
You blood capillaries lose a large amount of fluid to the surrounding tissues as well as a small portion of proteins. Under normal conditions, the output of liquids from capillaries is greater than their absorption. In this way, the excess fluid and proteins in the tissues are removed and returned to the blood through the lymphatic system,formed by a network of interconnected channels.
The lymphatic system consists of lymphatic capillaries, lymphatic vessels, lymphatic ducts (thoracic duct and right lymphatic duct) and lymph nodes. You lymphatic capillaries they are the smallest conducting vessels of the lymphatic system. They originate in connective tissue as microscopic blind-bottom vessels, which unite to form larger vessels, the lymphatic vessels. Lymphatic capillaries have a single layer of endothelial cells, while lymphatic vessels have three-layer walls that resemble the walls present in veins.
As in veins, lymphatic vessels present valves that guarantee the flow of lymph in a single direction. Lymph movement occurs thanks to external forces acting on the vessel walls, such as the massaging action of skeletal muscles. Between each valve of the lymphatic vessels, it is possible to notice a dilation, and, as there are several valves in these structures, the lymphatic vessel acquires the appearance of a necklace of beads.
The lymphatic vessels join and end in two large ducts, the thoracic duct and the right lymphatic duct. O thoracic duct it is the largest lymphatic vessel in our body and is the common trunk of almost all lymphatic vessels. O right lymph duct it is smaller and is responsible for transporting lymph from places that were not collected by the vessels that flow into the thoracic duct.
The thoracic duct and the right lymphatic duct flow into the junction of the left internal jugular vein with the vein left subclavian vein, and at the junction of the right subclavian vein with the right internal jugular vein, respectively.
In the course of lymphatic vessels, we find the lymph nodes, which are small oval bodies formed by lymphatic tissue and surrounded by capsules of connective tissue. The capsules protrude into the lymph nodes, forming structures called trabeculae. These trabeculae divide the parenchyma into compartments.
O parenchyma of the lymph node is formed by a cortical region, just below the capsule, and a medullary region, which is found in the center of the organ. The region through which the blood vessels in the lymph node it receives the name of hilo.
Lymph circulates inside the lymph node via a unidirectional pathway. It enters the organ through afferent lymph vessels that flow into the convex edge of the lymph node and exit through the efferent lymphatic vessels that come out of the hilo.
At the inside lymph nodes, there is a large amount of cells responsible for our defense, such as macrophages and lymphocytes. When lymph passes inside the lymph nodes, microorganisms and foreign particles are attacked by the Imune system. At a time when our body is fighting a infection, it is common for the lymph nodes to become swollen and tender.
Read too: Lymphoma, a type of cancer that starts in the lymphatic system.
Organs related to the lymphatic system
O spleen, tonsils and thymus they are three organs closely related to the lymphatic system. In them, the presence of a large amount of lymphoid tissue is observed, which, among other characteristics, stands out for the presence of lymphocytes. The spleen is related to functions such as destruction of Red Cells and participation in the immune response. The tonsils, in turn, act to protect the entry of the digestive system and respiratory against microorganisms. Finally, the thymus is the organ in which T lymphocytes complete their maturation.
Lymph
Lymph is the name given to the fluid lost from capillaries to surrounding tissues after entering the lymphatic system. It is characterized by being a fluid with composition very similar to the blood plasma, however, it differs from the latter for having a low concentration of proteins. In the lymph a large presence of leukocytes, which are the cells that act in the defense of our body. Among the leukocytes, the presence of lymphocytes stands out.
Lymphatic System Functions
The lymphatic system has fundamental functions for the functioning of the body, including:
Return to the bloodstream of important substances that left the capillaries and found themselves in the surrounding tissue.
absorption of lipids from the intestine to the intestinal lymph.
Body defense. In lymph nodes, microorganisms and foreign particles are destroyed by the action of the immune system. In these places we have the action of macrophages, which carry out the phagocytosis of foreign particles and also the activation of lymphocytes. Here we observe a joint work between the lymphatic system and the immune system.
Edema
In some situations, the amount of fluid in the tissues exceeds the capacity of the lymphatic system to ensure its return to circulation. This accumulation causes what we call edema. These edemas can have different causes, such as an excess of filtration in the capillaries or some obstruction of the lymphatic vessels.
Obstruction of lymphatic vessels can be observed, for example, in the case of elephantiasis, also called filariasis lymphatic. This disease is transmitted by the bite of a mosquito contaminated by the nematode called Wuchereria bancrofti. This worm lodges itself in the lymphatic system and interferes with the proper circulation of lymph, thus causing edema, which can affect limbs, sinuses, and scrotum. In this situation, we observed a large deformity in the affected region. If you want to know more about this type of accumulation in the body, read: What is edema?
By Vanessa Sardinha dos Santos
Biology teacher
Source: Brazil School - https://brasilescola.uol.com.br/biologia/sistema-linfatico.htm