The lymphatic system

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Which vessels connect the lymph nodes?

Bacterium

A single-celled organism that can be found everywhere in our surroundings. Some of them can cause diseases while others are essential to life.

Immune system

A group of organs and substances in your body that fight off infections and diseases.

Virus

A very small biological unit consisting of genetic material. It can only grow inside the cell of a living organism and can cause diseases and infections.

Gut

A long and curvy tube through which food travels from the stomach to the anus.

Liver

An organ in the body that produces important chemicals, stores nutrients and forms waste products.

Lymphatic system

The system of tissues, organs and vessels in the body that produce and store cells that fight disease, remove waste products from cells, and transport fluids and proteins that have escaped from cells back into the blood.

Lymph node

One of the small round pieces of tissue in the body that carries a fluid called lymph.

Spleen

An organ close to the stomach that destroys old red blood cells and produces white blood cells.

Tonsil

One of two spongy, round parts at the back of the mouth that assist in fighting infections entering through the mouth.

Adenoid

One of two large masses of tissue at the back of the nose and the throat.

Thymus

A large gland at the bottom of the neck that helps to develop the immune system in children and gets smaller as a person grows older.

Antibody

A substance produced by the body to fight disease.

Lymph

A clear liquid that contains white blood cells and passes through vessels in the body to keep bodily tissues healthy and carry off waste.

Perhaps you've had a bad cold, and felt sore and swollen under your jaw and on the side of your neck? Or, you've been to the doctor, who examined you by touching and squeezing there... ... or on the back of your neck, behind your ears, in your armpits, or your groin? What might get swollen there when you're ill are your lymph glands, or lymph nodes. Lymph-what?

you say. Lymph nodes. The lymph nodes are part of the lymphatic system, which helps your body with many things -- most of all to protect against infections and to rid the body of stuff it doesn't want. The lymphatic system consists of many different components, spread out in the body, doing different things. The most important ones, beside the lymph nodes, are...

The lymphatic vessels... The spleen... The tonsils... The adenoids... And the thymus.

Let's take them one at a time, ... starting with the lymph nodes. The lymph nodes are small, ranging from a few millimetres to a few centimetres, and shaped like - small beans. Inside the lymph nodes, there are masses of white blood cells, because here the immune system does most of its job. When bacteria, viruses or cancer-cells pass through a lymph node, white blood cells and antibodies attack and try to destroy them.

When there are many such substances coming through the lymph node, the white blood cells multiply. That's why the lymph nodes get swollen when you're ill. The lymph nodes are connected through the network of lymphatic vessels. The lymphatic system has its own vessels, just like the cardiovascular system has its blood vessels. Although the lymphatic vessels don't transport blood, but a transparent fluid called lymph.

The lymph nodes filter and purify the lymph as it passes through. The lymph transports, among other things, white blood cells... and fat. But most of the lymph is fluid soaked up from the space between the cells in your body. This is one of your body's ways of getting rid of excess fluid from the tissues.

The fat carried by the lymph has been absorbed from food by the intestines. The fat's destination is the liver, to be stored or used by the body as energy. But the lymphatic vessels aren't directly connected to the liver! First the fat must be transferred to the blood by some means. Up here, in the chest, the lymphatic system is connected to the cardiovascular system.

And the lymph is released into the bloodstream, to become part of the blood. The fat is carried to the liver, and the fluid can be absorbed by the tissues again. In this way the lymph is part of a cycle: Lymphatic vessels absorb it... ... hand it over to the blood... ... which then hands it back to the tissues, where it can be absorbed again.

The lymphatic vessels also lead to the spleen. The spleen sits in front of your left kidney, and is about the same size as your heart. The spleen is also part of the lymphatic system, and another place where the lymphatic system is connected to the cardiovascular system. Just as the lymph nodes filter the lymph, the spleen filters the blood. It fights intruders, using white blood cells from the lymphatic system.

From the moment we are born, and throughout childhood, our immune system rapidly develops. During this period, the lymphatic system is particularly active. Some parts of the lymphatic system are used almost exclusively during childhood. Then they regress, and reduce in size. This affects the thymus, which is a gland in the upper part of your chest.

And the tonsils, which are even higher up, at the root of your tongue, and in your throat. And the adenoids, behind your nose. The thymus, tonsils, and adenoids are all involved in developing the immune system during childhood, and regress after puberty. So.. the lymphatic system is a collection of several different things in your body: The lymph nodes, that filter the lymph; and in which white blood cells gather.

The lymphatic vessels, that transport important things like: White blood cells working for the immune system; Fluid from the tissues in the body; And fat from the intestines to the liver. The spleen, purifying blood, with the help of white blood cells. And the tonsils, the adenoids, and the thymus, which are involved in building the immune system during childhood. So, next time your neck feels swollen and sore, you know that it's just your immune system working.