Chapter 15 Lecture 4, Pgs

Lymphatic system Many additional substances, including fluid and protein molecules, that cannot enter or return through the capillary walls are returned to the blood as lymph

Lymph Specialized fluid formed in the tissue spaces that is transported by lymphatic vessels to re-enter the circulatory system

Lymph The lymph is drained into the subclavian veins through the right lymphatic duct and the thoracic duct * See figure 15-3, page 463 3/4 of the body drains through the thoracic duct, which is the largest lymphatic vessel in the body

Lymph The lymph system also includes the lymph nodes, thymus & spleen

Lymph nodes Lymph goes through nodes as it works its way back to the veins They are located in clusters along the pathway of lymph vessels * See figure 15-1, page 462

Lymph nodes Functions: 1. White blood cell formation 2. Filtration (defense)

Lymph nodes Lymph nodes will swell during bouts with infection Examples: swollen “glands” in the neck or throat area, armpit, or groin areas, or others

Lymph nodes Doctors will examine nodes for presence of cancer cells If found it probably metastasized

Thymus Small lymph tissue located in the mediastinum Important in the formation of T cells T cells help in immunity HIV infects and destroys T cells Person has little immunity

Tonsils Lymph tissue in the mouth & back of the throat; form protective ring around internal opening of nose & throat Help protect against bacteria that may invade tissues in that area

Tonsils Palatine- each side of throat * See figure 15-8, page 468 Pharyngeal- near back of nasal cavity (also known as adenoids) Lingual- near base of tongue

Tonsils May be chronically infected and have to be removed if they do not respond to antibiotics Tonsillitis- inflammation of the tonsils

Spleen Largest lymph tissue located high in the upper left quadrant just lateral to the stomach

Spleen Has a very rich blood supply (up to one pint) Filters, destroys old RBC’s, salvages iron to be used later, holds blood so it can be returned to the bloodstream if needed

Spleen It can be injured by trauma, especially if it is swollen or enlarged (protected some by ribs) It will enlarge (splenomegaly) during some diseases, like mono, scarlet fever, syphilis, typhoid fever

Spleen If injured, it may be life threatening because of internal bleeding Severe pain in the abdomen, pain down left arm Spleen may have to be removed (splenectomy) to stop loss of blood