The lymphatic system

Clean and Kill

Ducts and Drains

The lymphatic system is an extensive drainage system that returns water and proteins from various tissues back to the bloodstream.

It is comprised of a network of ducts, called lymph vessels or lymphatics, and carries lymph, a clear, watery fluid that resembles the plasma of blood.

Routemaster

The entire lymphatic system flows toward the bloodstream, returning fluid from body tissues to the blood.

If there were no way for excess fluid to return to the blood – extra cellular swelling.

The lymph vessels collect that excess fluid and carry it to the veins through the lymphatic system.

Why do we need the lymph?

This process is crucial because water, proteins, and other molecules continuously leak out of tiny blood capillaries into the surrounding body tissues.

This has to be drained, and so it returns to the blood via the lymphatic vessels.

These vessels also prevent the back flow of lymph fluid into the tissues.

Other jobs

The lymphatic system also defends the body from disease-causing agents such as viruses, bacteria, or fungi.

Harmful foreign materials are filtered out by small masses of tissue called lymph nodes that lie along the network of lymphatic vessels.

These nodes have lymphocytes (wbc), some types which produce antibodies, special proteins that fight off infection and its spread by trapping disease-causing germs and destroying them.

Transport of fatty acids

The Composition

Lymph is composed of water, protein molecules, salts, glucose, urea, lymphocytes, and other minor substances.

They are in every part of the body except the central nervous system

Size and Position

Lymph nodes are round or kidney-shaped, and range in size from very tiny to 1 inch in diameter.

They are usually found in groups in different places throughout the body, - neck, armpit, chest, abdomen, pelvis, and groin.

About two thirds of all lymph nodes and lymphatic tissue are within or near the gastrointestinal tract.

The major lymphatic vessel is the thoracic duct, which begins near the lower part of the spine and collects lymph from the lower limbs, pelvis, abdomen, and lower chest.

The Protectors

Neutrophils – most common 60-70% Lymphocytes – specialized 18-20% Monocytes – long term memory – 1-2% Basophils – super specialized – 0-1% Macrophages – the large killers

White coats

Lymphocytes are white blood cells in the lymph nodes that help the body fight infection by destroying foreign matter such as bacteria or viruses.

Two types are T-cells and B-cells

Spleen The spleen also plays an important part in a

person's immune system and helps the body fight infection.

Like the lymph nodes, the spleen contains antibody-producing lymphocytes.

The blood passing through the spleen carries damaged cells, white blood cells called macrophages in the spleen will destroy them and clear them from the bloodstream.

It helps control the amount of blood and blood cells as it’s the only lymph tissue through which rbc’s flow.

How does Lymph work?

It moves more slowly than blood, pushed along mainly by a person's breathing and contractions of the skeletal muscles.

The walls of blood capillaries are very thin, and they have many tiny openings to allow gases, water, and chemicals to pass through to nourish cells and to take away waste products.

Take out the Recycling

Lymph vessels recycle the interstitial fluid and return it to the bloodstream in the circulatory system.

The nodes contain macrophages, that destroy bacteria, dead tissue, and other foreign matter, removing them from the bloodstream.

After these substances have been filtered out, the lymph then leaves the nodes and returns to the veins, where it re-enters the bloodstream.

Immunity

When a person has an infection, germs collect in great numbers in the lymph nodes.

If the throat is infected - the lymph nodes of the neck may swell.

If the phagocyte cannot destroy all of the germs - a local infection in the nodes may result.

Cancer node?

The lymphatic system extends to the far reaches of the body, it also plays a role in the spread of cancer.

This is why lymph nodes near a cancerous growth are usually removed with the growth.