D2-3: The Lymphatic System September 8, 2010

The Lymphatic System This system is a collection of organs whose primary function is to collect extracellular fluid and return it to the blood. The main organs in this system include: ▫Bone Marrow ▫Lymph nodes ▫Thymus ▫Spleen ▫Tonsils

I. Vessels of the Lymphatic System Lymphatic capillaries are similar to blood vessels except they absorb: ▫Some of the fluid lost by the blood vessels ▫Dead cells ▫Pathogens These fluids and particles are known as lymph.

I. Vessels of the Lymphatic System Lymphatic vessels carry lymph throughout the body and eventually drain into the large neck veins of the cardiovascular system. Both the lymphatic and the cardiovascular systems work together to return fluids to the body as well as fight against pathogens with WBCs.

II. Other Parts of the Lymphatic System God also designed our bodies to have specialized Lymphatic organs. These again include: ▫Bone Marrow ▫Lymph Nodes ▫Thymus ▫Spleen ▫Tonsils

A. Bone Marrow As we talked about in our previous chapter, marrow is very important in the formation of red blood cells and white blood cells. Lymphocytes are a type of white blood cells that can help your body to fight pathogens and other viruses.

B. Lymph Nodes As lymph travels through its vessels they stop at lymph nodes. ▫These are small, bean-shaped masses of tissue that remove pathogens and dead cells from the lymph. ▫They contain two types of lymphocytes:  Killer T cells: Surround and destroy pathogens  B cells: Produce antibodies that attach to pathogens that clump up and are destroyed by other cells.

B. Lymph Nodes When bacteria or pathogens cause an infection, WBCs make their “rallying battle cry.” WBCs will multiply to fight off the infection in your body. The result it that your lymph nodes will often swell up and ache. ▫You, your parent, and your doctor can actually feel the result of this if you are sick.

C. Thymus The main gland of the lymphatic system. It produces mature T lymphocytes, which are ready to fight off infection. It is located behind the breastbone, just above the heart.

D. Spleen This is the largest lymphatic organ. As blood flows through it, lymphocytes attack and mark pathogens in the blood. It also produces, monitors, stores, and destroys blood cells. As RBCs are squeezed through the spleen the old cells are destroyed and can often be “recycled” into new blood cells.

D. Spleen The spleen has two important functions: 1.White Pulp  Produces WBCs to fight infection. 2.Red Pulp  Removal of damaged or defective RBCs Is it possible to live a healthy life without your spleen? Answer: ▫Yes ▫The spleen can sometimes be damaged or removed. ▫Other organs inside our bodies will take over the functions of the spleen. ▫An amazing gift from God!!!

E. Tonsils Small, rounded masses of lymphatic tissue located in the pharynx (throat)and in the passage from the mouth to the pharynx. Lymphocytes found in the tonsils can fight pathogens that enter the throat and lungs.

E. Tonsils Conditions that may result from tonsils: ▫Swelling  May swell with fight infection  Difficulty swallowing ▫Strep throat  Tonsils that are infected and covered with patches of white. ▫Tonsillitis  Infected tonsils  Difficulty breathing  Surgery may be needed with frequent infections

E. Tonsils