1. Functions

• drain all tissue fluids (interstitial) and return them to the blood
• transports large lipids and retun them to the blood
• nonspecific and specific immunity

2. Lymphatic capillaries and vessels

• a closed-end system paralleling blood vessels
• interstitial fluid flows into lymph capillaries
• fluid is now called lymph
• can return lost proteins to the blood
• lymphatic vessels become two main lymphatic ducts

- right lymphatic duct - drains upper right side of body
- thoracic duct - drains upper left side of body and entire inferior body

3. Lymph nodes

• located in clusters along lymphatic vessels
• lymph percolates through these pea-shaped organs
• has a dense connective tissue capsule
• a framework of reticular fibers with sinuses
• an outer/inner cortex and medulla
• the outer cortex has lymphatic nodules which contains B cells

- germinal center of nodules is site of B cell production

• the inner cortex contains T cells
• medulla has medullary cords containing B cells and plasma cells

4. Lymph flow through a lymph node

• afferent lymphatic vessel
• into cortical sinuses lined with reticular fibers
• into medullary sinuses
• into efferent lymphatic vessels

5. Specialized lymph nodes

• Thymus

- in mediastinum
- contains lymphocytes
- programs T cells
-  atrophies at puberty

• Tonsils

- forms a ring in the oral cavity

• Spleen

- white pulp - assists in lymphocyte production
- red pulp - blood reservoir and destruction of RBC