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Lymph Nodes and Fluid

Rivers of the Human Body

Aug 18, 2009 Dan Paul Burgess

The lymphatic system is critical to the movement of fluid throughout the body. When disease or injury hinders its function there are health consequences.

The lymphatic system drains fluid (Lymph) from between the cells of the body back into the circulatory system where it provides needed proteins.

Lymphatic Fluid

Lymphatic fluid (lymph) is a clear, watery fluid that collects between the cells of the human body. The fluid originates in the capillary bed and the cells themselves. The lymph consists of proteins produced in the cells that are too large to be reabsorbed into the vessels, water, waste products from cellular metabolism, and foreign invaders such as bacteria.

While 90 percent of the fluid circulating in the cells is returned to the blood in the vascular system, 10 percent remains in the lymphatic spaces.

Lymphatic Drainage System

Obviously the fluid cannot be allowed to accumulate without dramatic results. Think of a system of rivers that drain a valley and then flows into increasingly larger rivers until eventually the fluid is emptied into the ocean. This is the way the lymphatic system works in the body eventually emptying into the vascular system where the needed proteins are deposited in the blood.

Unlike the river system the lymphatic system works against gravity and unlike the circulatory system that carries blood through the body the lymphatic system does not have a central pumping mechanism like the heart. As a consequence the lymphatic drainage system has a series of valves that prevent reverse flow. The average human body has 600-700 of these lymph nodes which also act as filters.

The lymph nodes filter the lymph fluid removing many bacteria and holding them where they can be destroyed by lymphocytes. The nodes also filter out foreign substances such as cancer cells. This explains why they become swollen and tender as a result of infection and many cancers.

Disease or Injury Interrupts the Flow

The nodes eventually may become overwhelmed by the numbers of cancer cells or infectious bodies to the point that the filtering becomes inadequate and the infection or cancer then proceeds to the remainder of the body.

Although the lymph nodes can swell or contract as needed once they are damaged or destroyed they are not replaced with new ones. Damage may occur as a result of infection or can be mechanical destruction from things such as surgery for breast cancer. A consequence of damaged lymph nodes is an interruption of the flow of lymph. Structures intended to prevent back flow and filter may not only become ineffective but may actually begin to act as dams blocking the flow. The diagnosis normally associated with this situation is known as lymphedema.

References

Mei, R., Ridner, S., and Armer, J., Post-Breast Cancer Lymphoma: Part 1, American Journal of Nursing, 109(7), 48-53.

The copyright of the article Lymph Nodes and Fluid in General Medicine is owned by Dan Paul Burgess. Permission to republish Lymph Nodes and Fluid in print or online must be granted by the author in writing.

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