The Lymphatic System

In contrast to the lymph system, the blood flows through a circulatory system and is pumped through the body by the heart. The blood plasma flows through the capillary walls of the arteries. It fills the intercellular spaces, supplying the tissue with nutrients and oxygen.

The lymph nodes are found in strategically important areas of the body, e.g., in the armpits and groin. They act as filter stations in which the lymph is cleaned. The central monitoring station of the immune system, they are the home to multitudes of defence cells which detect pathogens in the lymph as it flows in and initiate their destruction. When the defensive battle is at its height, the lymph nodes often swell because the lymphocytes multiply.

The main lymph vessels empty into the bloodstream at the clavicle veins.

The tonsils, similar to the lymph nodes, are equipped with defence cells. Their task is to intercept pathogens which enter the throat area through the air or with food. The tonsils also swell when the immune defence is in a fight:

Many pathogens enter the gastro-intestinal tract with food. Peyer's plaques in the intestinal mucous membranes are full of defence cells which fight the pathogens on the site.

The thymus gland is the "school" for the T cells. This is where the scouts are trained to recognize a particular antigen, the "wanted" poster of a pathogen. The name T cells was derived from the word thymus.

The bone marrow is the body's blood factory. This is also where the stem
cells for the various white blood cells responsible for the immune defence are formed. The B cells are named for the bone marrow.

The spleen is part of the lymphatic and blood vessel system. Among other tasks, it breaks down overage blood cells. One-third of the lymphocytes are concentrated in the spleen, and one-third of the phagocytes also come to maturity here. The spongy organ is therefore an important element of the immune defence.

The lymph vessels begin with one closed end as finely branching capillaries. They join to make larger lymph pathways leading to the centre of the body. Excess fluid, by-products of metabolism, particles and pathogens leave the tissue and intercellular spaces via the lymph vessels. Lymph, which consists primarily of blood plasma, is propelled through the body by muscle contractions.