What are lymph nodes? You will find an exhaustive answer to the question in the materials of the article. In addition, we will talk about the structure of the presented organ, as well as the causes of its inflammation, possible consequences, and so on.
General information
What are lymph nodes? The lymph node is called the peripheral organ of the lymphatic system, which performs the function of a natural filter. Through it flows all the lymph coming from various parts and organs of the body. In the human body there are several groups of such nodes, which are called regional.
Lymph node size
Externally, the lymph nodes look like round, oval, bean-shaped or sometimes ribbon-like formations. Their sizes vary between 0.5-50 millimeters and more. As you know, such peripheral organs are painted in a grayish pink color. Lymph nodes are located only along the lymphatic vessels and are located in clusters of up to ten pieces near large veins and blood vessels.
Appearance
Human lymph nodes are covered with a connective tissue membrane, from which the so-called trabeculae or beams extend into the body. They represent a kind of supporting structure. It should be specially noted that the peripheral organ itself, which acts as a natural filter, consists of stroma. It is formed from the reticular connective tissue, on which there are process cells that form a three-dimensional network. In addition, the stroma consists of phagocytic substances (or macrophages), represented in the lymph nodes by several varieties.
The internal structure of the lymph node
On the section of the lymph nodes, two main zones are immediately distinguished. Closer to the shell is a cortical substance. It distinguishes the surface part and the region of the deep cortex (or the so-called paracortical layer). The brain substance is referred to the inner zone of the lymph node.
The entire space of this organ is filled with lymphoid tissue. In the area of the superficial cortex, which is closer to the shell, small nodules or follicles are located. It should be noted that they have a central light part (germination center), where B-lymphocytes are differentiated and antigen-dependent proliferation, as well as a dark surface one, which contains a large number of densely spaced and relatively small lymphocytes.
Principle of operation
In the paracortical zone, the lymphocytes are evenly and very densely. T-lymphocytes predominate in this part of the organ. Here they undergo antigen-dependent differentiation and proliferation. As for the brain substance, the accumulations of lymphoid tissue in it are represented by brain strands (or flesh cords), where B-lymphocytes migrate from the surface cortex.
The principle of operation of this peripheral organ is as follows: the lymph flows to the nodes along the vessels suitable from the convex side, and flows to the nodes from the concave part. At the same time, inside the lymph node, it leaks rather slowly through spaces called sines. They are located between the membrane and trabeculae, as well as lymphoid tissue.
As well as vessels, the internal space of the node has its own lining, which is formed by littoral or coastal cells. As a rule, their processes are directed into the sinus, where they begin to come into contact with reticular cells. It should be noted that, unlike ordinary vessels, the sinuses do not have a free cavity, because it is completely blocked by a three-dimensional network. Due to this structure of the lymph, getting into the node, slowly seeps out, which contributes to its thorough cleansing of foreign bodies. This process also occurs thanks to macrophages located along the very edge of the lymphoid clusters. By the way, while passing through the sinuses (medulla), the lymph is fully saturated with antibodies producing plasma strands (medulla).
What are lymph nodes for?
What are lymph nodes, we found out. Now I want to talk about why these bodies are needed at all. The fact is that the leaking lymph brings the so-called foreign antigens to the node. As a result, this leads to the development of an immune response in the organs of reactions. Depending on the type and nature of foreign bodies, such reactions can actively develop in external or internal zones. This leads to a barely noticeable or strong increase in the size of the nodes. Thus, it can be safely noted that the presented peripheral organs are a kind of barrier to the spread of not only various infections, but also a cancerous tumor. After all, protective cells that take an active part in the destruction of foreign antigens and other substances are able to mature in the node.
Where are the lymph nodes located?
Lymph nodes (photos are presented in this article) are in the human body in large enough groups, of which there are about ten pieces. They are located so as to prevent the development of various infections and cancerous tumors. For this reason, the nodes are located near the most important organs and systems for life, namely in the elbow and knee bends, in the armpits and inguinal region. In addition, they are located in the neck, chest and abdominal cavity. Thus, the lymph nodes provide complete protection against various infections and head tumors.
Types of lymph nodes
It should be noted that such a filtration system is not only in the above places. Lymphocapillaries permeate all internal organs. However, they perform the same functions.
So, in the human body there are several groups of lymph nodes, namely:
- intrathoracic;
- bronchopulmonary;
- ulnar;
- splenic;
- paraaortic;
- mesenteric;
- iliac (external, internal, as well as general);
- inguinal (superficial and deep);
- femoral
- popliteal.
Why are lymph nodes enlarged?
The causes of enlarged lymph nodes are a variety of diseases. In this case, it should be emphasized that the lump that appears indicates the disadvantage of precisely the zone in which it is located. Most often, an increase in lymph nodes is associated with any infection. In addition, such a pathology occurs against the background of tumor damage.
So, let's take a closer look at why and with which diseases there is an increase in lymph nodes in children and adults:
- Purulent processes. As a rule, with this deviation, the so-called acute lymphadenitis occurs. Most often, this occurs as a result of the ingress of microbes from wounds that are located in the zone of a peripheral organ. The main symptoms of this inflammation include the appearance of pain on palpation and redness of the skin. If at this moment you do not open the formed cone, then the shell of the node will tear, and pus will penetrate into the surrounding tissue, resulting in a rather serious complication called phlegmon.
- Enlarged lymph nodes in children quite often indicate the presence of tuberculosis. As a rule, with such a disease, cones are formed in the chest cavity and on the neck.
- Often the cause of enlarged lymph nodes in young children is the microbe Bartonella. The carriers of this bacterium are cats, whose scratches can often be observed in a child. It is through these wounds that the microbe very quickly spreads through the lymph vessels and enters the nodes, which subsequently grow and become quite painful. Thus, a purulent wound that does not heal for a long time, as well as a lump appearing nearby, should always suggest the development of a “cat scratch” disease.
- With ARVI in adults and children, there can be up to several groups of enlarged lymph nodes. The reason for this deviation is the excessive response of the immune system to the invasion of any viruses in the patient's body. It should be noted that the lymph nodes in such situations do not increase very much, but when palpated, they are quite painful.
- Sexually transmitted diseases, in particular syphilis, also cause enlarged lymph nodes. In this case, the patient can observe bumps in the inguinal region, as well as ulcers on the genitals. Unlike other diseases with syphilis, enlarged lymph nodes can be painless, and therefore invisible to humans.
- Long-lasting enlarged lymph node groups may indicate the presence of serious diseases such as listeriosis, brucellosis, HIV infection, or mononucleosis.
Tumor enlargement
A tumor of the nodes can occur due to lymphoproliferative diseases (if the tumor originally originated from the lymph node), as well as from metastatic lesion. The first deviation, first of all, is lymphosarcoma and lymphogranulomatosis. Lymph nodes in such diseases increase to four to five centimeters and become quite dense. However, when feeling, the resulting bumps are not painful. By the way, with an initial increase in intra-abdominal or intrathoracic lymph nodes, such diseases may not be recognized.
To summarize
Now you know what lymph nodes are. It should be especially noted that an increase in the organs of the peripheral system should immediately alert the patient. The reason for this is simple: such a pathological condition indicates that dangerous processes are taking place in the human body. In this case, it is recommended to immediately consult a doctor and undergo a complete medical examination.