The lymphatic organs of the human

The lymphatic organs of the human

Image: “Anatomy of the Lymphatic System” by philschatz. License: CC BY 4.0

The lymph

The filtered from the capillaries fluid from the tissue is transported through the lymphatic system. Lymph is tissue water and contains proteins as well as excess cell fluid, metabolites and foreign substances. It also contains many nutrients and transports, among others:

  • sodium
  • calcium
  • creatinine
  • glucose
  • lipase
  • phosphate
  • catalase
  • ureas

If the flow of the lymph stops, substances like that provide fibrinogen for the lymph to clot. The lymphocytes are encapsulated. In addition, it contains the lymphocytes for defense. Every day about two liters of lymph are produced.

Strictly speaking, the lymph is that Intermediate link between tissue fluid (intercellular fluid) and blood plasma and has a slightly cloudy and milky appearance. Lymph is divided into Lymphserum (supernatant lymph) and chyle (high-fat lymph from the digestive tract).

The lymph comes from extracapillary fluid that is no longer absorbed by the bloodstream. It is first collected in the lymphatic capillaries that merge into larger vessels. These vessels then lead to the lymph nodes. The lymph nodes have the task of collecting and filtering the lymph. Care here laxative vessels (vasa efferentia) for the lymph to be passed on.

The lymphatic system

The lymphatic system is a system of fine vessels. It consists of the lymphatic vessels and the lymphatic organs. The task of the lymphatic organs is to form the lymphocytes, which are indispensable for the body’s defense.

At first are primary and secondary lymphatic organs to distinguish. Belong to the primary lymphatic organs thymus and bone marrow. They are characterized by specialized tissue in which the Training and maturation of B and T lymphocytes expires. Before the birth is also the liver a primary lymphatic organ. The lymphocytes formed there migrate into the secondary lymphatic organs.

The secondary lymphoid organs are the Lymphoid follicles of the mucous membranes counted, as well as the Peyer’s plaques (are in the small intestinal mucous membrane), Appendix vermiformis (Cecum), the tonsils (Almonds), lymph node and the spleen (more precisely, the white pulp).

The lymphatic vessels, on the other hand, drain the lymph from the tissues. The task of the lymphatic system is the exchange of substances. The lymphatic system is too not self-contained. An example of a closed system is the bloodstream. The lymphatic vessels are located in large parts next to arteries and veins, which facilitates the exchange. The wall of the lymphatics is thin and permeable. So it is possible to take substances from the environment, which are then transported.

lymph node

Every human being has about 600 lymph nodes, many are located on the neck, shoulders, groins and near the gastrointestinal tract. Lymph nodes are very small with a size of less than 1 mm. But they increase in size when it comes to illnesses.

Picture: “Structure and Histology of a Lymph Node” by philschatz. License: CC BY 4.0

In such cases, the lymph nodes can grow up to 3 cm. primary follicles however, are spherical cell clusters of lymphocytes. This creates contact between lymphocytes and antigens (foreign structures). Once the ability to defend is available Secondary cells with germ cells the speech. Here the lymphocytes mature and become defense cells.

Filtering the lymph

In the Inguinal lymph nodes (Nodi lymphatici inguinales) The lymph is filtered from the legs, abdominal wall and buttocks. In the Axillary lymph nodes (Nodi lymphatici axillares) The filtering of the lymph takes place from the anterior and posterior abdominal wall and the arms. The Lymph nodes on the neck (Nodi lymphatici cervicales) are responsible for filtering the lymph from the head.

From the mentioned lymph nodes, the lymph is directed to the inside of the body. For this reason, a change in the lymph nodes for the physician is a first indication of which organ is affected. Each organ has its own nearby lymph node, which changes in pathological processes. Likewise, diseases can migrate through the lymph and attack other lymph nodes.

The spleen (Lien) – lymphatic organ

The spleen is the largest lymphatic organ and has a weight of about 150-200 g. It is about 12 cm long and 7 cm wide with a thickness of about 4 cm. It lies under the diaphragm in the left upper abdomen in a solid capsule of connective tissue. The spleen itself is permeated with connective tissue and consists of reticular fibers and cells.

Their task is the formation of white blood cells (leukocytes) and their storage. It also filters over red blood cells (erythrocytes) from the blood. The spleen also detects bacteria and viruses and is therefore important for the immune system.

Vital, it is not for adults, however. However, people who have had their spleens removed are, among other things, much more susceptible to infections. The spleen has two functions and is accordingly in the Red and the white pulp divided. The organ has a similar cleansing function as the lymph nodes, but it is “responsible” for the entire bloodstream.

Red and white pulp

In the spleen are the Malpighian corpuscles, also called spleen nodules, which form the white pulp. The strongly perfused spaces represent the red pulp. The white pulp produces the lymphocytes, in the red pulp the old erythrocytes are broken down.

In addition, the red pulp is the storage location for platelets and also stores leukocytes, which are then dispensed as needed. In addition, pre-damaged blood cells are degraded or substances are secreted, which can cause disease.

The thymus

The thymus is located behind the sternum and is a lymphatic organ without a duct. The organ consists of two asymmetrical lobes, which are interconnected. By connective tissue structures, the lobes are further divided into small sections. Here, T lymphocytes are characterized by their defense tasks.

Picture: “Location, Structure, and Histology of the Thymus” by philschatz. License: CC BY 4.0

In newborns, the thymus is still quite large (about 30 g in weight), but then forms during puberty, until it weighs only about 18 g in adulthood. It is normal for the thymus to become greasy and the glandular tissue to disappear. These fat deposits have no function.

The tasks of the thymus are superordinate and include the formation and differentiation of the T-lymphocytes, which are particularly important in childhood for immune defense. Under the microscope, a bark with high cell density is found in the tissue of the thymus. Inside is Mark with the Hassal corpuscles, whose function is not yet clear.

The tonsils (tonsils)

The tonsils are also lymphatic organs. They are in the oral cavity and in the throat. The lymphatic organs include the Palatine tonsils (Tonsillae palatinae), the Pharyngeal tonsils (Tonsilla pharyngealis), the Tube almonds (Tonsilla tubaria) and the Tongue Tongue (Tonsilla lingualis). They all make up the Waldeyer’s throat ring, which is strongly supplied with colds and is visible when the mouth is open.

All tonsils included Lymphfollikel. In them, B lymphocytes multiply for specific defense. Intensive contact with pathogens leads to an even stronger formation of lymphocytes. This causes the almonds to swell. This is a process that is extremely painful.

Image: “Locations and Histology of the Tonsils” by philschatz. License: CC BY 4.0

The tonsils are an important part of the immune system. They are designed to prevent pathogens from entering. In children, the tonsils are much larger, but from puberty, they are much smaller. In adults, the tonsils have hardly any important functions, since they are mainly used to build up the immune system. In studies, palatine tonsils are well visible on swelling when the mouth is open. By the way, tonsils take over the task of an early-warning system and control the various ways in which germs can invade.

Structure of the tonsils

The tonsils belong to the mucosa-associated lymphoid tissue (MALT). On closer inspection crypts are visible (depressions). They serve to enlarge the surface. In adults, the total surface of the tonsils reaches an area of ​​300 cm².

Picture: “Mucosa-associated Lymphoid Tissue (MALT) Nodule” by philschatz. License: CC BY 4.0

The surface consists of multi-layered squamous epithelium. In these wells with a spongy surface pathogens can more easily “get stuck”. The immune system known pathogens are recognized at this point. However, unknown pathogens can continue to penetrate. The tonsils are, strictly speaking, a collection of lymph nodes that are connective tissue-like. In terms of structure, however, all tonsils are the same. They are also all below the mucous membrane.

Diseases of the lymphatic system

If a disease of the lymphatic tissue is not detected early and treated, it can spread. The best example is the tonsillitis, which, if left untreated, can cause serious health damage, such as a endocarditis.

Lymphoid cancer – Hodgkin’s disease

Hodgkin’s disease is one of the aggressive Ca diseases and affects the lymphatic system. Symptoms include swollen lymph nodes that are not painful. Other signs include fatigue, weight loss and fever. The sooner the disease is diagnosed, the greater the chances of recovery.

Non-Hodgkin lymphoma

In this disease, there is an enlargement of the lymph node, also called lymphoma. Lymphoma can be benign and also malignant. Non-Hodgkin’s lymphoma, however, only refers to lymphomas that are malignant, but that are not non-Hodgkin’s lymphoma.

Spleen diseases

The splenomegaly is a possible disease of the spleen. It is an enlargement of the spleen. Nevertheless, splenomegaly is not a disease of its own but can be the result of various triggers. These can be infectious diseases such as glandular fever. But a sepsis or a rheumatic disease comes as a cause in question.

Theoretically, moreover, a blood congestion is possible. The blood accumulates in the spleen, as may be the case as a result of liver cirrhosis. Ultimately, however, a tumor disease is possible, which leads to a proliferation of the spleen.

Diseases of the tonsilla

Picture: “Tonsillitis” by Michaelbladon. License: Public Domain

tonsillitis is the tonsillitis, which affects mostly the palatine tonsils. The doctor speaks of the Angina tonsillaris. This is an acute bacterial infection. It is often caused by streptococci, but other pathogens are possible. These include staphylococci or pneumococci.

Particularly susceptible are persons whose immune defense is weakened. With them it comes then repeatedly to Tonsillitis. Even in children, the disease is not uncommon, which can result in an increase in the tonsils. The result is a misplaced breathing, which may require surgical removal of the tonsils. For mild symptoms, gargling with soothing solutions may be sufficient as an analgesic treatment. Even home remedies often suffice (quark wrap) or herbal medicines. For strong symptoms, however, the use of antibiotics is required.

Popular exam questions to the lymphatic organs

The solutions are below the sources.

Which answers are correct?

1. The lymph …

  1. … can coagulate.
  2. … contains no proteins.
  3. … is just tissue water.
  4. … contains mostly sodium.
  5. … is always milky.

2. The red pulp …

  1. … stores lymphocytes.
  2. … produces lymphocytes.
  3. … removes leukocytes.
  4. … gives off platelets.
  5. … is outside the spleen.

3. The thymus …

  1. … is vital in youth and old age.
  2. … doubles its weight through fat storage.
  3. … must first train in newborns.
  4. … retains the glandular tissue for life.
  5. … is important in children for the training of the immune system.

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Christina Cherry
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