Written by: Liz Paton, MSc

Lymphatic System Overview

The lymphatic system is an intricate network of vessels, nodes, tissues and organs throughout our bodies that protect us from infection and disease. Lymph fluid travels through our bodies to rid it of toxins, waste and unwanted materials. It is essential for keeping us healthy.  

Lymphatic System Anatomy

The primary function of the lymphatic system is to return the lymph from tissues back into the blood stream in order to keep the body healthy. The system is comprised of organs, lymph nodes, lymph vessels and lymph fluid.  

Lymphocytes

A lymphocyte is a type of white blood cell that plays a role in our immune system. There are three major types of lymphocytes called B-lymphocytes, T-lymphocytes and natural killer (NK) cells. B-lymphocytes produce antibodies that defend against bacteria, viruses and toxins. T-lymphocytes destroy the body’s own unhealthy cells. Natural killer cells target and kill virally infected and cells that have the tendency to form tumours.   

Organs of the Lymphatic System

The organs of the lymphatic system are involved with filtering blood and the development of lymphocytes. These organs include the spleen, tonsils, and thymus. Lymphatic tissue can also be found in the appendix and within the gastrointestinal tract. The spleen works as a blood filter, filtering out old red blood cells and foreign material from the blood stream. The role of the thymus is to mature and develop the T-lymphocyte cells, one of the primary types of lymphocytes. Red bone marrow works similarly to the thymus and also matures the T-lymphocyte cells. Tonsils are the small organs found in the back of your throat. If you still have them, you can see them when you open your mouth wide. Containing an abundance of white blood cells, the tonsils help stop germs from entering the body through the mouth and nose.  

Lymph Fluid

The word “lympha” is Latin for “water”. Lymph is the whiteish-yellow transparent fluid that flows through the lymph vessels and nodes. It is made up water, proteins, lipids, carbohydrates, and most importantly, white lymphocytes. White lymphocytes are a type of white blood cell and the body’s main type of immune cell.    

Lymph Nodes

Your body is filled with hundreds of lymph nodes which work as filters removing waste products, foreign material, harmful bacteria and cancerous cells from your blood. The filtered fluid then returns your blood circulation. Lymph nodes are great indicators of your health and swell up when you are unwell, although this is not always a cause for concern!  

Lymph Vessels

Lymph vessels are the thin tubes that carry lymphatic fluid and white blood cells throughout the body. These vessels contain valves which prevent backwards flow and thus the system is able to exist without a central pump (unlike the circulatory system which relies on the heart). The lymph vessels can be divided into two different systems: the superficial vessels and deep vessels. The superficial vessels drain into deep vessels which then drain the internal organs. Lymph fluid drains proximally (towards the centre of your body), passing through the lymph nodes.