LYMPH: MAIN FUNCTIONS AND CHARACTERISTICS - ANATOMY AND PHYSIOLOGY - 2025

The lymph is a slightly alkaline fluid that functions as an interstitial fluid in the human body, ie, flowing in the space between one cell and another. Lymph is channeled into the lymphatic vessels, through which it can flow and eventually return to the bloodstream.

In this line, one of the functions of lymph is to help clean the cells of the body, collecting waste and infectious or potentially harmful organisms. This fluid starts from the blood and is therefore coagulable. It travels both through the lymphatic vessels and through the veins, contributing to the exchange of nutrients between the body's tissues and the blood.

In turn, some large molecules metabolized in the liver can only pass into the bloodstream through the lymph, since the lymphatic vessels have larger pores than the blood vessels.

There is a type of lymph known as chyle that specializes in transporting fat from the intestine to the bloodstream. Unlike the other crystalline lymph located in the rest of the body, this one has a whitish appearance due to the presence of fatty acids. (Vorvick, 2016).

In general, the lymph not exclusive to humans. This liquid can also be found in any mammal, with a similar composition and fulfilling the same functions that it fulfills in the human body.

Lymph formation and recovery

In order to move blood through the arteries and veins, the heart must apply some pressure with each beat. This pressure is transmitted through the arteries to the capillaries, which are porous, very thin-walled vessels where oxygen, nutrients, and fluids are transported to the cells of the body.

As the fluids drip through the capillaries, they seep into the surrounding tissues, becoming interstitial fluids.

Thus, these fluids are recovered again by the capillaries and back into the bloodstream. This is done to prevent the cell space from flooding and the blood concentration in the arteries and veins from being too high due to constant fluid loss.

There are other vessels known as lymphatic capillaries that are located in a bulging way between the blood capillaries. These vessels are small porous tubules that are responsible for channeling lymphatic fluids.

The pressure in the lymphatic vessels is lower than in the blood vessels and surrounding tissues. For this reason, fluid that leaks from the blood tends to enter the lymphatic capillaries.

While the blood vessels join to form venules and veins that are responsible for returning blood to the heart, the lymphatic capillaries progressively join to form larger lymphatic vessels. These are responsible for transporting the lymph from the tissues to the center of the body.

All the lymph in the body eventually returns to one or two of the channels located in the upper part of the body.

Thus, the thoracic ducts are responsible for collecting the lymph that comes from the legs, the intestine and internal organs.

In this way, as the thoracic duct rises through the chest, it is responsible for collecting the lymph contained in the organs of the thorax, the left arm and the left side of the head and neck (Olszewski, 1985).

For its part, the right lymphatic duct is responsible for collecting lymph from the right side of the chest, the right arm, and the right side of the head and neck.

In this regard, both the thoracic and right lymphatic ducts converge in the bloodstream, where the jugular veins of the head and arms and the subclavian veins meet in the upper chest.

Lymph composition

Lymph contains various substances, including proteins, salts, glucose, fats, water, and white blood cells. Unlike blood, lymph does not normally contain red blood cells, but it is clottable once it comes into contact with the bloodstream.

The composition of lymph varies widely depending on where it originates in the body. In the lymphatic vessels of the arms and legs, the lymph is crystalline and its chemical composition is similar to that of blood plasma. However, lymph differs from plasma in that they contain less protein (Drinker & Field, 1933).

The lymph found in the intestines is whitish in appearance, due to the presence of fatty acids that are absorbed from food.

This mixture of lymph and fat is known as chyle. There are special lymphatic vessels located around the intestine called lacteal vessels that are responsible for collecting chyle. The lacteals drain the chyle and store it in a reservoir in the lower part of the thoracic duct known as the chyle cistern.

Lymph flows through the lymphatic vessels and passes through the lymph nodes. The human body has up to 600 lymph nodes in the shape of small beans, scattered in a bulging and strategic way throughout the body.

Lymph nodes are responsible for filtering bacteria, cancer cells and other possible agents that are harmful to the body that are contained in the lymph (Harrington, Kroft, & Olteanu, 2013). An alteration of the lymph can cause lymphatic cancer.

Lymph functions

Intermediate in the transport of oxygen, food, proteins and hormones

Its interaction occurs between the cells present in all the tissues of the body, to which it distributes its content and later takes the carbon dioxide and other residues of the metabolic process contained in them, taking the blood and later to the circulatory system.

Keeps the cells of the body hydrated

The lymph is responsible for keeping the body's cells hydrated and destroying any microorganism or external agent that tries to attack the lymph nodes.

In addition, it performs the function of transporting antibodies from the lymph nodes to other organs that may be affected by an infectious process. In this sense, lymph plays a fundamental role for the body's immune system.

Carries fat and soluble vitamins

In the case of chyle, the lymph fulfills the important task of transporting fat and fat-soluble vitamins.

The lymphatic capillaries present in the intestinal villi are called lacteal, and are responsible for the absorption and transport of the fat contained in the chyle.

It is responsible for carrying protein macromolecules to the blood

Lymph also carries macromolecules of plasma proteins synthesized in liver cells and hormones produced in endocrine glands into the blood.

These liver molecules could not pass through the narrow pores of the blood capillaries, but they can be filtered through the lymphatic capillaries to reach the blood.

Maintains the ideal blood volume

Another important function of the lymph is to keep blood volume stable. At the moment in which this volume is reduced in the vascular system, the lymph rushes from the lymphatic system to the vascular system to increase it again and thus regulate it (Kumar, 2012).

Related bodies

The organs that make up the lymphatic system are divided into two groups, one of primary organs and the other of secondary organs.

Primary organs

• The Thymus: This lymphoid organ is the most important in the body's immune system. It is made up of two lobes and is located between the heart and the trachea. During the first months of life, its size is large in proportion to the rest of the body and other organs. However, once sexual maturity is reached, its size reduces.

Its main function is to form the white cells that make up the lymph, called T cells, which are responsible for identifying any agent that is harmful to the body and eliminating it.

• The Bone Marrow: the marrow is the soft material located in the cavities of the bones. It is a network of connective tissue, fibers, fat cells, blood vessels and blood-producing cells, for this reason, the marrow is responsible for producing both red and white cells, including the lymphocytes that make up the lymph.

Both T cells and B cells contained in the lymph are produced in the marrow. Young T cells travel to the thymus until they reach maturity, and B cells remain in the marrow during their maturation process, until they are released and take their place in the lymphatic system.

B cells are white blood cells that are sensitive to antigens and their function within the lymph is to produce antibodies to fight them. An antigen can be any chemical that elicits an immune system response. The most common antigens are toxins, foreign proteins, particulate materials, and microorganisms such as viruses and bacteria.

B cells are memory cells, that is, if at some point they have to fight an antigen, they store the information related to it. In this way, if they have to fight the antigen again, they already know how to do it and release antibodies more quickly.

Secondary organs

Secondary organs related to lymph include the lymphatic vessels, lymph nodes, lymphoid tissue aggregates, and the spleen.

These organs are responsible for fulfilling three main functions: absorbing the fat transported in the lymph, regulating lymphatic fluids and serving as agents of the body's immune system (Smith & Foster, 2017).

References

1. Drinker, CK, & Field, ME (1933). Lymphatics, Lymph and Tissue Fluid. Oakland: Williams & Wilkins.
2. Harrington, A., Kroft, SH, & Olteanu, H. (2013). Lymph Nodes. New York: Bradfor and Bigelow.
3. Kumar, P. (February 24, 2012). Preserve Articles. Retrieved from What are the Functions of Lymph ?: preservearticles.com.
4. Olszewski, W. (1985). Peripheral Lymph: Formation and Immune Function. Michigan: CRC Press.
5. Smith, D., & Foster, D. (2017). Pet Education. Retrieved from Lymphatic System Anatomy and Function: peteducation.com.
6. com. (2015, September 6). Study.com. Obtained from What is a Lymph? - Definition & Anatomy: study.com
7. Vorvick, LJ (September 3, 2016). Medline Plus. Retrieved from Lymph system: medlineplus.gov.