Ch. 7.9 - Lymphatic System and Immunity
Cisterna chyli
A large sac-like chamber at the lower end of the thoracic duct that receives lymph (a fluid called chyle) from the lower body and intestines.
Immunity
The body's ability to resist infection, disease, or other unwanted biological agents. This is a primary function of the lymphatic system, which produces and circulates immune cells.
Lacteals
Specialized lymphatic capillaries in the small intestine that absorb dietary fats (lipids), which are not absorbed directly into the bloodstream.
Lymph
The clear, watery fluid that flows through the lymphatic system. It's formed from the interstitial fluid (fluid surrounding cells) that enters lymphatic vessels. It contains white blood cells (lymphocytes), proteins, and sometimes fats.
Lymph nodes
Small, bean-shaped organs that filter lymph and house large numbers of white blood cells. They act as critical checkpoints, trapping and destroying pathogens (like bacteria and viruses) before the lymph is returned to the blood.
Lymphatic system
A network of tissues, vessels, and organs that work together to move lymph back into the circulatory system. Its main functions are fluid balance (returning excess fluid to the blood), fat absorption, and immune defense.
Lymphatic vessels
A network of tubes (similar to blood vessels) that transport lymph throughout the body. They start as tiny capillaries and merge into progressively larger vessels.
Right lymphatic duct
One of the two large ducts that drains lymph into the bloodstream. It collects lymph from the right side of the head, neck, chest, and the right arm, emptying it into the right subclavian vein.
Spleen
The largest lymphatic organ, located in the upper left abdomen. It filters blood (not lymph), removing old or damaged red blood cells and storing white blood cells and platelets. It also plays a key role in activating the immune response.
Thoracic duct
The main and largest lymphatic vessel in the body. It collects lymph from the entire lower body, the left side of the head, neck, and chest, and the left arm, emptying it into the left subclavian vein. It begins at the cisterna chyli.
Thymus
A gland located in the chest, just behind the sternum. It is most active during childhood and is the primary site where T-lymphocytes (T-cells), a crucial type of white blood cell, mature.
Tonsils
Clusters of lymphatic tissue located in the pharynx (throat). They form a ring of defense, sampling bacteria and viruses that enter the body through the mouth or nose and helping to trigger an immune response.