Tissue fluid and lymph: how are formed and how different
Our body is a complex system, and the deeper our knowledge of its structure, the more amazing and mysterious it seems. The internal environment of the body, where there is a direct exchange between the cells, is the tissue fluid and lymph. How is the internal environment formed, what is its composition and function? This article will tell you about this.
The main components of the
environment The true internal environment of the body is the tissue fluid that occupies the intercellular spaces. Blood as a component of the internal environment does not come into contact with the cells of the body. Capillary walls firmly separate it and retain the composition. Each cell also has a cytoplasmic membrane. Mechanisms of membrane transport provide a metabolism, but this happens through the transition of all substances into the interstitial fluid. Lymph is another component of the internal environment. From the course of biology we know that lymph is a fluid that is in the lymphatic system, the second most important system of the body. Simply put, these environments are connected by a closed chain: blood - interstitial fluid - cell - lymph - blood. Exactly this way there is an exchange of metabolic products, hormones, biological substances and gas exchange.
All cells of our body, and their order of a hundred trillion, are surrounded by a liquid medium filled with nutrients. This is the tissue( interstitial) fluid. It has its own composition and stable isoionium( ion concentration).In our body, its volume is about 20 liters, and this is up to 29% of the total weight. Its composition is diverse and depends on the specific nature of the surrounding tissue( cerebrospinal fluid, pleural and pericardial bags).The main feature of the composition - in the intercellular fluid there are few proteins, many dissolved sugars, amino acids and enzymes. The main part is water with dissolved salts, electrolytes, oxygen, carbon dioxide, the products of vital activity of our cells.
Intercellular fluid - the precursor of lymph
From the intercellular space part of the tissue fluid comes back into the blood, and part is sent to the lymph vessels. Once in there, it becomes peripheral lymph. Passing through one or two lymph nodes, it becomes intermediate, and before returning to the bloodstream( for example, in the thoracic duct) it is already central lymph. In this case, from the peripheral to the central lymph is filled with shaped elements. In our body, the order of two liters of lymph, which consists of water and uniform elements: leukocytes, monocytes, segmented neutrophils, platelets, eosinophils and other cells. In addition, there are fats, proteins and carbohydrates in the lymph. The percentage composition of these components of lymph varies depending on its source tissues.
Blood - the internal environment of the body
Our blood is enclosed in a system of blood vessels and capillaries, and the circulatory system has a closed bloodstream. It consists of a liquid fraction - a plasma - and a fraction of the shaped elements. In an adult male blood of about 40-47% of the elements, a woman - up to 42%.Blood in our body is up to 8% of the body weight, and this is 6 liters. The blood plasma has a constant composition: 91% - water, up to 8% - proteins, the rest - electrolytes, lipids, glucose, hormones and bioenzymes, vitamin complexes and dissolved gases. Form elements are specific cells( red blood cells, leukocytes, platelets).
Circulation of liquids
Circulation of blood, tissue fluid and lymph is generally simple and is shown in the figure. Part A illustrates blood circulation and lymph drainage, part B - how tissue fluid and lymph form. From the blood capillaries under the influence of hydrostatic and oncotic pressure, the liquid fraction of blood plasma enters the intercellular space, where it forms colloidal and fibrous formations. Some of these substances pass into cells from the tissue fluid . How does lymph form further? Some of the liquid enters the lymphatic capillaries. The outflow of lymph is facilitated by contractile movements of the walls of the vessels and the presence of valves in them. Then the lymph passes through the lymph nodes, where it is purified from toxins and enriched with lymphocytes, and then through the large lymphatic ducts it returns to the bloodstream. The scheme of formation of tissue fluid and lymph, its outflow is presented in the following illustration.
Water exchange mechanism
In the tissue, the movement of blood is not performed on all capillaries: some of them are closed, and some are open. It is this that explains how tissue fluid and lymph are formed in a single tissue site. In the arterial part, the fluid is filtered into the intercellular space and there is accumulation. As the pressure created by excess fluid increases, the capillaries are squeezed and "closed".In this case, other capillary fields, lymphatic, are opened. The free liquid phase of the tissue space passes into the lymphatic ducts and the pressure in this area decreases, which leads to the opening of the blood capillaries.
Functions of blood, lymph, tissue fluid
Description of the value of the internal environment for the normal functioning of our body will take more than one page. We list only the main functions:
- Providing the homeostasis of the interstitial space.
- Protein, lipid and carbohydrate metabolism.
- Gas exchange, transportation of products of hydrolysis of nutrients.
- Provision of liquid redistribution.
- Humoral connection of tissues and organs, lymphatic system and blood.
- Implementation of mechanisms of all kinds of immunity.
- Regulation of energy metabolism by transfer of energy-supplying biomolecules of adenosine triphosphate.