What are the components of the lymphatic system?

Lymph

Lymph is a watery, colorless fluid that flows through the lymphatic system. Also known as lymphatic fluid, it is essentially a collection of extra fluid that drains out from cells and tissues into the body and isn’t reabsorbed into the capillaries. Lymph contains nutrients as well as cellular waste. Substances present in the lymph include proteins, fats, minerals, cancer cells, pathogens, and damaged cells. Lymph also carries lymphocytes, which are infection-fighting white blood cells.  

Lymph nodes 

Lymph nodes play a key role in monitoring lymph and cleansing it of cancer and damaged cells as the fluid filters through them. There are about 600 lymph nodes scattered throughout the body, some nearer the skin and others deeper inside the body. These bean-shaped glands store lymphocytes and other immune system cells that attack and destroy pathogens and other hazardous substances present in lymph. 

Lymphatic vessels

Lymphatic vessels are thin-walled tubes or vessels that form a complex network throughout the body. Also known as lymphatics or lymph vessels, these tubes are responsible for moving lymph to different parts of the body. One-way valves present in the lymphatic vessels keep the lymph moving in the right direction.  

Collecting ducts

The lymphatic vessels empty their content into two collecting ducts- right lymphatic duct and thoracic duct, which then release the contents into the two subclavian veins located beneath the collarbones. These veins converge to form the superior vena cava, the major vein that carries blood from the upper body to the heart. 

Spleen

The largest lymphatic organ in the body, the spleen is responsible for storing and filtering blood, and producing white blood cells that protect the body from infections. The spleen is located on the left side of the body under the ribs and above the stomach. 

Thymus

The thymus, which is located in the upper chest beneath the breastbone, is where T-cells (pathogen-fighting cells) differentiate and mature fully. It is most active before puberty. 

Tonsils and adenoids

These lymphoid organs work by trapping pathogens from the surrounding air we breathe and the food we eat.

Tonsils (located in the back of the throat) and adenoids (located just behind the nasal cavity) form the body’s first line of defense against most invaders by trapping pathogens present in the air you inhale and the food you ingest. Adenoids are only active in childhood. 

Bone marrow

Bone marrow is the soft spongy tissue present in the center of some bones, such as hip and thigh bones, breastbone, and backbones. It consists of stem cells and plays a crucial role in synthesizing red blood cells, platelets, and white blood cells. 

Peyer’s patches

Peyer’s patches are the small masses of lymphatic tissue found in the mucous membrane that lines the small intestine.

Appendix

The appendix helps in housing good bacteria. After an infection is cleared, the appendix releases the bacteria to repopulate the gut.