Composition of Lymph
Introduction :-
Composition of Lymph – Lymph is typically a clear, colorless fluid. It is composed of 4% solids and 96% water. Lymph also contains some blood cells. A microscopic analysis of lymph shows that between 500 to 75,000 leucocytes, or primarily lymphocytes, are present in a significant amount per cubic millimeter. There are no blood platelets in the area. The noncellular component of lymph (fasting) is made up of the following components.
Properties of Lymph :- It is best to think of lymph as altered tissue fluid. The fluid that appears transparent and watery that is contained in lymphatic tubes is called lymph. It is created when components from blood capillaries access tissue spaces. Following a high-fat meal, the thoracic duct lymph appears milky because the alimentary canal absorbs tiny droplets of emulsified fat.
Solids- Composition of Lymph :-
Though they make up a smaller portion of the liquid portion of lymph, the solid components are essential to lymph’s immune system function and fluid balance maintenance. The main constituents of lymph’s solid makeup are:
Composition of Lymph – Proteins :- The total protein level is 2.5% to 4.5%, which is about half the plasma level.
Albumin is the most abundant protein in lymph and is involved in maintaining fluid balance and osmotic pressure. Globulins include immunoglobulins or antibodies, which are essential for the immune response. Fibrinogen is not as concentrated as plasma, but it still plays a role in the clotting process.
Composition of Lymph- Fats :- These lipid-rich molecules are in charge of transferring dietary lipids and are especially prevalent in lymph originating from the intestines (chyle). While fasting, fat content is minimal; however, following a high-fat diet, it may reach 5–15%.
Composition of Lymph- Cells :- B cells and T cells, which are crucial for adaptive immunity, are among the lymphocytes, which make up the majority of lymph cells.
Macrophages are immune cells that phagocytose—that is, take up and destroy—pathogens, cell debris, and foreign objects. Antigens produced from pathogens are delivered by dendritic cells. T cell activation is aided by these antigen-presenting cells.
Others Composition of Lymph – The total amount of phosphorus is 11.8 mg (plasma 22 mg), inorganic phosphate is 5.9 mg (plasma 5.6 mg), creatinine is 1.4 mg (plasma 1.37 mg), urea is 23.5 mg (plasma 21.7 mg), and calcium is 9.84 mg (plasma 11.7 mg). Non-protein nitrogen-containing substance is 34.8 mg (plasma 32.6 mg). There are also antibodies and enzymes.
Formation of Lymph :-
Lymph is produced from interstitial fluid due to the porous nature of lymph capillaries. Nine out of ten fluid units enter the venous end of blood capillaries from the arterial end when blood travels through these capillaries in the tissues.
Additionally, lymph capillaries, which have greater permeability than blood capillaries, receive the final one-tenth of the fluid.
Thus, lymph is essentially composed of the same components as interstitial fluid, including protein, when it travels via lymph capillaries. Because of their bigger size, proteins found in the interstitial fluid are unable to penetrate blood capillaries. Thus, these proteins get into lymph channels, which can also let big particles through. Greater proportions of protein and lipids accumulate in the tissue fluid of the gastrointestinal system and liver. Thus, a significant amount of lipids and proteins reach the gastrointestinal tract and liver’s lymphatic capillaries. Larger arteries therefore contain more lipids and proteins in their lymph. Because water and electrolytes are absorbed, the lymph becomes concentrated as it moves through the lymph nodes. The lipids and proteins, however, are not absorbed.
Factors Involves - Formation of lymph :-
Anything that raises the quantity of tissue fluid will accelerate the development of lymph because lymph is generated from this fluid. The production of lymph is dependent on physical conditions. It excludes any essential secretory processes.
The development of lymph is caused by the following factors:
1. Capillary Hydrostatic Pressure (CHP) :- The force that blood applies to capillary walls
The rate of lymph production increases with an increase in capillary pressure. Venous blockage is one instance of this. However, after a while, the rate decreases as a result of more fluid building up in the tissue gaps and the tissue fluid’s subsequent rise in hydrostatic pressure.
2. Lymphatic Capillary Permeability :- Any circumstance that increases the capillary wall’s permeability will result in the formation of additional tissue fluid and, ultimately, lymph. Capillary permeability is increased by the following elements:
• Temperature rise: Capillary permeability increases in a given area when the temperature rises.
• Chemicals that directly affect the capillary wall include proteases, foreign proteins, histamine, and extracts from foods like crayfish, strawberries, mussels, leeches, etc. These substances damage the capillaries and make them more permeable.
• Decreased oxygen supply: Because of the increased permeability of the vessels, lymph flow rises when there is a shortage of oxygen. It most likely works by causing harm to the capillary endothelium. These include anoxia, anemia, and blood stasis brought on by vascular congestion.
3. Capillary Oncotic Pressure (COP) :- The osmotic pressure exerted by plasma proteins in the capillaries, primarily albumin, pulls fluid from the interstitium back into the capillaries. The higher the COP, the less fluid leaves the capillaries.
4.Better results will be obtained from hypertonic solutions. When hypertonic solutions are added to the blood, the blood will initially retain more fluid in the tissue gaps, which will result in an even greater increase in blood volume. There will be a significant increase in blood pressure along with further diluting of plasma colloids. In this sense, compared to normal or hypotonic solutions, hypertonic solutions will significantly boost the generation of lymph. For this, solutions of NaCl, glucose, Na2S04, etc., may be utilized.
5. Muscle Activity and Movement :- Musculoskeletal muscle contractions and other body movements: Muscle contractions move lymph through the lymphatic system by compressing the lymphatic vessels and preventing backflow.
Lymph flow rate :-
Lymph moves into blood at an average rate of roughly 120 mL per hour. The right lymphatic duct transports about 20 mL per hour, while the thoracic duct receives 100 mL per hour from this.
Interstitial pressure, artery pulse, intra-thoracic pressure, and muscle massage all influence the regulation of lymph flow rate.
Aspects Increasing the Flow of Lymph:
1. An increase in interstitial fluid pressure stimulates the flow of lymph.
2. Capillary pressure in blood.
3. The lymph capillary surface area measured by dilation.
4. The lymph capillaries’ permeability.
5. The tissues’ functional activity.
Function of Lymph :-
The transparent liquid known as lymph, which moves via the lymphatic system, performs a number of vital roles in the body. The following are the main purposes of lymph:
1. Nutritive Function : Areas not supplied with blood are nourished and oxygenated by it. The lacteal and lymphatic capillaries of the gastrointestinal system allow dietary lipids and fat-soluble vitamins to be absorbed from the gut. The lymphatic system allows chyle, is a milky fluid made of absorbing lipids, to enter the bloodstream.
2. Immune System Support :- The body’s protective cells are the lymphocytes and monocytes. Bacteria are also eliminated from tissues by the lymphatics. White blood cells, particularly lymphocytes, which are essential for the immunological response, are transported by lymph. Additionally, it transports antigens—foreign substances that elicit an immunological response—to lymph nodes so that the latter can process them and trigger an immune reaction.
3. Transmission of proteins in bloodstream :- Tissue compartments release proteins into the blood via the lymph. The lymphatic system collects all proteins that leak out of the capillaries into the spaces between them and delivers them to the bloodstream. The osmotic balance between blood and interstitial fluid is maintained in part by this process.
4. Drainage Function :- It attempts to maintain a constant amount of fluid and substances in the tissues by excreting excess tissue fluid and metabolic products.