Lymph

Illustration of a lymph capillary

Lymph is a clear, colorless fluid that circulates through the lymphatic system, a network of tissues and organs that help rid the body of toxins, waste, and other unwanted materials. The primary function of the lymphatic system is to transport lymph, a fluid containing infection-fighting white blood cells, throughout the body.

Composition

Lymph is similar to blood plasma in composition but contains a lower concentration of proteins. It is primarily composed of:

• Water
• Electrolytes
• Proteins
• Lipids
• Lymphocytes
• Metabolic waste products

Formation

Lymph is formed when the interstitial fluid is collected through tiny lymph capillaries located throughout the body. This fluid is then transported through larger lymphatic vessels and eventually returned to the bloodstream.

Diagram of capillary microcirculation

Function

The primary functions of lymph include:

• Maintaining fluid balance: Lymph helps return excess interstitial fluid to the bloodstream, preventing edema.
• Immune response: Lymph transports antigens and lymphocytes to lymph nodes, where immune responses can be initiated.
• Absorption of fats: Lymphatic vessels in the intestines, known as lacteals, absorb dietary fats and transport them to the bloodstream.

Lymphatic Circulation

Lymph circulates through the body in a one-way system that begins with lymph capillaries and progresses through larger vessels, eventually draining into the thoracic duct or the right lymphatic duct, which empty into the subclavian veins.

Lymph Nodes

Lymph nodes are small, bean-shaped structures that filter lymph and house lymphocytes. They are distributed throughout the body and play a crucial role in the immune system by trapping foreign particles and pathogens.

Lymphatic system diagram

Clinical Significance

Disorders of the lymphatic system can lead to various medical conditions, including:

• Lymphedema: Swelling due to lymphatic obstruction.
• Lymphadenopathy: Enlargement of lymph nodes, often due to infection or malignancy.
• Lymphoma: A type of cancer that originates in the lymphatic system.

Related Pages

• Lymphatic system
• Lymph node
• Lymphocyte
• Immune system