Lymph is part of the lymphatic system, which is the most important transport system for the body besides the blood circulation. It is responsible for detoxification, defense, purification of the body and complete health monitoring. It can influence many complications and disease conditions. The main purpose of lymph is to eliminate pathogens, as it destroys pathogens together with lymphocytes in the lymph node.
What is the lymph?
The term lymph comes from the Latin word lympha, which means clear water. The plural form “lymphae” served as the name of Roman fresh water deities. Lymph names the light yellow, slightly milky turbid and watery fluid found in the lymphatic vessels that acts as an intermediate between the tissue fluid and the blood plasma. It collects in the tissue crevices and is also known as interstitial fluid and tissue fluid. Compared to blood plasma, it contains less protein. It is composed of electrolytes, proteins, chylomicrons and the white blood cells, also known as leukocytes.
Anatomy and structure
Lymph originates from extracapillary fluid that leaks into the intercellular space through the blood capillaries and cannot return to the bloodstream. It washes around all cells. The cells extract from it the substances they need and excrete their waste products into the lymphatic fluid. Therefore, the lymph contains waste substances that are to be removed from the intercellular space and therefore differs from the intercellular fluid. The lymph collects in the lymph capillaries, which join together to form larger vessels and lead to the lymph nodes. In the lymph nodes, the lymph is collected and filtered. By means of draining vessels, the fluid leaves the lymph nodes. The lymphatic vessels unite to form the lymphatic breast duct, into which also flow the lymphatic vessels that transport the absorbed fat of the intestine. The contents of the lymphatic duct spill into the subclavian vein on the left side, and through this route the lymph returns to the general circulation. Two to three liters of lymph fluid per day are produced by the human body. Lymph consists of lymph plasma and cells. Its components are calcium, phosphate, potassium, creatinine, glucose, sodium, urea, catalase, diastase, lipase, dipeptidase, fibrinogen and fibrin precursors. Lymph from the stomach or intestines usually has a cloudier color and is called chyle.
Function and tasks
The most important function of lymph and the lymphatic system as a whole is the transport of nutrients and waste products. With its lymphatic vessels serving as pathways, the lymphatic system plays the most important role for transport in the body, along with the circulation of blood. The lymph nodes are where the disposal of pathogens, foreign bodies and bacteria takes place. The lymph handles the removal of solutes, proteins, and lipids, and plays an important role in the immune system because it transports foreign bodies and germs to the lymph nodes, where lymphocytes respond to them. The lymph and lymphatic system are responsible for detoxification, tissue drainage and immune defense. All substances that cannot be drained directly from the tissues into the vascular walls of the bloodstream because of their molar mass or hydrophobicity are transported by means of the lymph. Excess fluid from the tissues is drained through the lymphatic vessels. Thus, the lymph also takes over the transport of lipids absorbed by the intestine, which first pass through the lymphatic duct, from where they enter the veins and liver to be fed to the metabolism. The lymph assumes a very important function in the immune system, as it responds to pathogens by producing lymphocytes, which can then fight them throughout the body. This proliferation of specific cells, called T cells and B cells, in the lymph node is called the germinal center reaction.
Diseases
Because new tissue fluid is constantly being formed, its removal through the lymphatic vessels can cause problems. Disease can cause more fluid to leak from the capillaries than normal, and thus the fluid cannot be removed as quickly. One such disorder of the lymphatic system is called lymphedema. These are swellings that occur when the fluid in the tissue cannot drain away.This means that fluid is stored in the tissue. The lymph accumulates and the tissue swells. The extremities are increasingly affected by lymphedema, but edema can also occur in other parts of the body. Very dangerous can be pulmonary edema, which can lead to drowning in one’s own lymph, which has accumulated in the alveoli. Pulmonary edema can occur when the left side of the heart is weakened and blood stasis forms in the small circulatory system. Lymphangitis refers to a disease of the lymphatics that is caused by bacteria and results in inflammation of the lymphatics. Lymphadenitis defines inflamed lymph nodes. Tumors can also spread through the lymphatic system. Cancer cells are transported from a primary tumor via the lymphatics and form metastases. The spread of tumor cells through the lymphatics is also known as lymphogenic metastasis. To contain metastasis, lymph nodes are often surgically removed in patients with cancer.
Typical and common diseases
- Hodgkin’s disease
- Blood poisoning
- Lymphedema
