Lymphatic System

Lymphatic System• A network of lymphatic vessels, lymph nodes,

and various other lymphoid organs and tissues scattered throughout the body

Lymphatic vessels

• The function of the lymphatic vessels is to pick up this excess tissue fluid, now called lymph, and return it to the bloodstream

• The lymphatic vessels, also called lymphatics, form a one-way system, and lymph flows only toward the heart

Lymph ducts• Lymph is transported through

successively larger lymphatic vessels until it is finally returned to the venous system through one of the two large ducts in the thoracic region

- The right lymphatic duct drains the lymph from the right arm and the right side of head and thorax

- The large thoracic duct receives lymph from the rest of the body

• Both ducts empty the lymph into the subclavian vein on their own side of the body

Lymphatic vessels

• Like the veins of the cardiovascular system, the lymphatic vessels are thin-walled, and the larger ones have valves

• The transport of lymph depends entirely on the skeletal muscles and the pressure changes in the thorax during breathing, therefore, there is no pump for the lymphatic system

Lymph nodes• The lymph nodes help protect the body by:- removing foreign material such as bacteria

and tumor cells from the lymphatic stream - producing lymphocytes that function in the

immune response• As lymph is transported toward the heart, it is

filtered through the thousands of lymph nodes that cluster along the lymphatic vessel:

- large clusters are found in the inguinal, axillary and cervical regions of the body

Other lymph organs

• Lymphoid organs includes: spleen, thymus gland, tonsils and Peyer’s patches of the intestine as well as bits of lymphatic tissue scattered in the epithelial and connective tissues

• Although all lymphoid organs have roles in protecting the body, only the lymph nodes filter lymph

Spleen• The spleen is a blood-

rich organ that filters blood

• It is located in the left side of the abdominal cavity and extends to curl around the anterior aspect of the stomach

• It is the largest lymphatic organ

Spleen

• The spleen filters and cleanses blood of bacteria, viruses and other debris

• Its most important function is to destroy worn out red blood cells and return some of their breakdown products to the liver

• Other functions of the spleen include storing platelets and acting as a blood reservoir

Thymus

• Function at peak levels only during youth, it is a lymphatic mass found low in throat overlying the heart

• The thymus produces hormones, thymosin, and others, that function in the programing of certain lymphocytes so they can carry out their protective roles in the body

Tonsils

• Are small masses of lymphatic tissue that situated at either side at the back of the human throat

• Their job is to trap and remove any bacteria or other foreign pathogens entering the throat

Peyer’s(pie’er) patches

• It resemble tonsils, are found in the wall of the small intestine

• The macrophages of Peyer’s patches are in an ideal position to capture and destroy bacteria, thereby preventing them form penetrating the intestinal wall