If there is a system in the body, then there is something that fills it. The activity of the branches of the structure depends on the quality of the content. This position can be fully attributed to the work of the human circulatory and lymphatic systems. The he althy content of these structures is an integral factor in the stable functioning of the whole organism. Next, we will analyze in more detail the importance of blood and lymphatic vessels. Let's start with the latest.
General information
Human lymphatic vessels are represented by different structures that perform certain functions. So, allocate:
- Capillaries.
- Large trunks (thoracic and right ducts).
- Extra- and intraorgan vessels.
Also, the structures are of muscular and non-muscular type. The flow rate and pressure (hemodynamic conditions) are close to those that occur in the venous bed. If we talk about the structure of the lymphatic vessels, then it is necessary to note the well-developed outer shell. Valves are formed due to the internal coating.
Capillary
This lymphatic vessel is differentsufficiently permeable wall. The capillary is capable of sucking up suspensions and colloidal solutions. The channels form networks that represent the beginning of the lymphatic system. Connecting, capillaries form larger channels. Each formed lymphatic vessel passes to the subclavian veins through the neck and sternum.
Move content along channels
The movement of lymph through the lymphatic vessels is carried out along the cervical duct into the venous bed. In the thoracic region, there is an outflow from virtually the entire body (except the head). Both ducts enter the subclavian veins. In other words, all the fluid that enters the tissues returns to the blood back. In this regard, as the movement of lymph through the lymphatic vessels, drainage is carried out. When the outflow is disturbed, a pathological condition occurs. It is called lymphoedema. Its most characteristic features include swelling in the limbs.
System functions
Lymphatic vessels and nodes primarily ensure the maintenance of constancy in the internal environment. In addition, the system performs the following functions:
- Transports nutrients from the intestines to the veins.
- Provides communication between blood, organs and tissues.
- Takes part in immunological processes.
- Provides the return of electrolytes, water, protein to the blood from the intercellular space.
- Neutralizes harmful compounds.
Nodes run along the course of the lymphatic vessels. They contain liquid. lymph nodesprovide fluid production and barrier-filtration protection (producing macrophages). The outflow is regulated by the nervous sympathetic system.
Interaction of structures
Located in close proximity to the blood, lymphatic capillaries begin blindly. They are part of the structure of the microvasculature. This causes a close functional and anatomical connection between the blood and lymphatic vessels. From the hemocapillaries, the necessary elements enter the main substance. From it, in turn, various substances penetrate into the lymphocapillaries. These are, in particular, the products of metabolic processes, the breakdown of compounds against the background of pathological disorders, cancer cells. Enriched and purified lymph penetrates into the bloodstream. This is how the internal environment in the body and the intercellular (basic) substance are updated.
Differences in structures
Small blood and lymphatic vessels have different diameters (the latter are larger). The endotheliocytes of the former are 3-4 times larger than those of the latter. Lymphcapillaries do not have a basement membrane and pericytes, and end blindly. These structures form a network and flow into small extraorganic or intraorganic channels.
Postcapillaries
Intraorganic efferent channels are muscleless (fibrous) structures. Each such lymphatic vessel has a diameter of about 40 microns. Endotheliocytes in the channels lie on a weakly expressed membrane. Under it are elastic and collagen fibers that pass into the outershell. Post-capillary channels function as drainage.
Extraorgan beds
These vessels are larger in caliber than the previous ones and are considered superficial. They belong to the structures of the muscular type. If the superficial lymphatic vessel (Latin - vasa lymphatica superficialia) is located in the region of the upper zone of the trunk, neck, face, then there are quite a few myocytes in it. If the channel passes through the lower body and legs, then there are more muscle elements.
Medium Structures
These are muscle type channels. The structure of the lymphatic vessels of this group has some features. All three shells are quite well expressed in their walls: outer, middle and inner. The latter is represented by endothelium lying on a weakly expressed membrane, subendothelium (it contains multidirectional elastic and collagen fibers), as well as plexuses of elastic fibers.
Valves and shells
These elements closely interact with each other. The valves are formed thanks to the inner shell. The basis is a fibrous plate. In its center there are smooth muscle elements. The plate is covered by endothelium. The median sheath of the ducts is formed by bundles of smooth muscle elements. They are directed obliquely and circularly. Also, the shell is represented by layers of connective (loose) tissue. These fibers form the outer structure. Its elements blend into the surrounding fabric.
Thoracic duct
This lymphatic vessel haswall, the composition of which is similar to the structure of the inferior vena cava. The inner shell is represented by endothelium, subendothelium and a plexus of elastic internal fibers. The first lies on a discontinuous weakly expressed basement membrane. The subendothelium contains poorly differentiated cells, elastic and collagen fibers that are oriented in different directions, as well as smooth muscle elements. The inner shell in the thoracic duct formed 9 valves that promote the promotion of lymph to the veins of the neck. The middle shell is represented by smooth muscle elements. They have an oblique and circular direction. Also in the shell there are multidirectional elastic and collagen fibers. The outer structure at the diaphragmatic level is four times thicker than the inner and middle structures combined. The shell is represented by loose connective tissue and bundles of smooth myocytes located longitudinally. The superficial lymphatic vessel enters the jugular vein. Near the mouth, the wall of the duct is 2 times thinner than at the diaphragmatic level.
Other items
There is a special area between two valves located side by side in a lymphatic vessel. It's called lymphangion. It is represented by the muscular cuff, the wall of the valvular sinus and the site of attachment, in fact, of the valve. The right and thoracic ducts are represented as large trunks. In these elements of the lymphatic system, myocytes (muscle elements) are present in all membranes (there are three of them).
Feeding the walls of the ducts
In the outerthe sheath of the blood and lymphatic channels has vascular vessels. These small arterial branches diverge along the integument: the middle and outer in the arteries and all three in the veins. From the arterial walls, capillary blood converges into veins and venules. They are located next to the arteries. From the capillaries in the inner lining of the veins, blood moves into the venous lumen. The nutrition of the large lymphatic ducts has a peculiarity. It lies in the fact that the arterial branches are not accompanied by venous ones, which go separately. Vessels are not found in venules and arterioles.
Inflammation of the lymphatic vessels
This pathology is considered secondary. It is a complication of purulent-inflammatory processes of the skin (furuncle, carbuncle, any purulent wound) and infections of a specific type (tuberculosis, syphilis, and others). The course of the process can be acute or chronic. Also isolated nonspecific and specific inflammation of the lymphatic vessels. The disease is characterized by malaise, weakness. Patients also have a fever. A characteristic symptom of pathology is soreness in the lymph nodes. The causative agent of pathology can be any bacterium of the pyogenic type (E. coli, enterococcus, staphylococcus aureus). The disease is diagnosed without much difficulty. Therapeutic measures are prescribed in accordance with the stage of the pathology. Sulfonamides and antibiotics are used as a conservative method. In advanced cases, the superficial lymphatic vessel is drained through the opening of the abscess.
Tumor
Hodgkin's disease - lymphogranulomatosis - affects mainly young people (15-10 years old). Symptoms of the pathology in the initial stages are absent, and the enlarged lymph nodes of the patient do not bother. As the disease progresses, metastasis occurs. The tumor spreads to other lymph nodes and organs, among which the spleen is usually the first to suffer. After that, signs of pathology begin to appear. In particular, the patient develops fever, general weakness, sweating, skin itching, weight loss. The disease is diagnosed by examining the leukocyte formula, as well as biopsy material.
Lymphadenopathy
Distinguishing this pathology from others is quite simple. In some cases, however, difficulties may arise with enlarged cervical elements. Lymphodenopathy is divided into reactive and neoplastic - non-inflammatory and inflammatory. The latter are classified into infectious and non-infectious diseases of the lymphatic vessels. They accompany diffuse pathologies in the connective tissue, allergies, rheumatoid arthritis. A reactive increase in the lymph nodes indicates cell proliferation due to the immune response to autoimmune, allergic, toxic attacks or an infectious process of an inflammatory nature. Against the background of a tumor, an increase in structural elements is caused by infiltration with malignant cells that come from other organs (with lymphocytic leukemia or cancer metastasis) or arise in the system itself against the background of malignant lymphomas and lymphosarcomas. Pathologiesmay be generalized or limited. The latter, however, can pass into the former. First, lymphogranulomatosis is referred to as limited lymphadenopathy, and then, after a while, it becomes generalized. The reactive group includes a fairly wide range of pathologies that are a diagnostic feature.
Ductal sarcoma
This is another malignant tumor. Lymphosarcoma can appear at absolutely any age. As a rule, it begins with an increase in lymph nodes on one side. The tumor process is characterized by a fairly high rate of progression, active metastasis and a particular malignancy. Within a short time, the patient's condition may deteriorate significantly. The patient has a fever, rapidly decreases body weight, sweating increases at night. Diagnosis consists in histological and cytological studies of the affected lymph node.
