The lymphatic system is one of the most developed in the body. Its function is to clean out the waste working much like the circulatory system. While the lymphatic system cleans, the immune system defends the body from disease. It too works closely with the circulatory system and depends on the lymphatic system to produce lymphocytes the main weapon of defense.
The lymphatic system is made up of nodes located in the neck, thigh and arm pits and act as filters. Cells causing diseases accumulate in these nodes where they are digested by lymph cells. These nodes are where the lymphocytes are located. They are the white blood cells of the immune system that make antibodies which eat the disease causing agents.
It is an open system interacting with the other systems of the body. Starting at the capillaries the fluids of the lymphatic system begin collecting the toxins to be delivered to the nodes by way of vessels that form into the thoracic duct which is attached to the largest blood vessel in the body, the superior vena cava.
The lymphatic system works in conjunction with the muscular system. The more movement the more efficient the system. Therefore, when inactive for any length of time the system slows down causing fluid to collect in the lower extremities.
The immune system recognizes foreign entities in the body on the molecular level. It is made up of innate and adaptive functions.
All organisms have an innate immune system. It is the bark of a tree, the skin of animals and the cell wall of microbes. It is the initial defense of the body and is not adaptive, which means it does not change. Also, special chemicals in saliva, mucus and digestive acids are part of this system. Other cells of the body have phagocytes which eat any foreign matter that enters the organism.
The second line of the body’s defense is the adaptive immune system. When the innate system cannot contain the toxins this systems responds. It contains memory cells each depending on the blood type of the animal. These lymphocytes, like T-cells which migrate to the thymus gland, are produced in the bone marrow. Birds have B-cells which can be found in their bursa which is a part of the intestine.
If both fail systems fail the body may die.
Milwaukee area residence can find more detailed information about the lymphatic and immune systems of animals at the Milwaukee Public Museum, the Milwaukee Public Library and at the Milwaukee County Zoo.