Lymphatic System and Immunity, Ch20 Flashcards
Lymph is collected in vessels called what, which merge to form what? What are their names?
Lymph-collecting vessels, which merge to form the larger lymph trunks. Lumbar, intestinal, jugular, bronchomediastinal, subclavian. 9 in total.
The intestinal and lumbar trunks all drain into what large vessel? This vessel and other lymphatic trunks drain into one of two what?
Cisterna chyli. Lymphatic ducts. The cisterna chyli and trunks from the left side of the body drain into the thoracic duct, the largest lymphatic duct, which drains all of the lower body as well as the left side of the upper body. The remaining trunks from the right upper side drain into the right lymphatic duct
What are the three basic functions of the lymphatic system?
Regulation of interstitial fluid volume, absorption of dietary fats, and immune functions.
Why do lymphatic vessels make up a low-pressure circuit? What features work with it?
There is no main pump to drive lymph through the vessels. Most of them are working against gravity. Lymphatic valves prevent backward flow. The vessels are often lodged between muscles, where contractions massage lymph toward the heart. Contractions of smooth muscle found in the walls of lymph-collecting vessels also help.
Lymphatic vessels begin in the tissues with what, which form weblike networks that surround blood capillary beds? Characteristics?
Lymphatic capillaries. They are blind-ended, which makes the lymphatic vasculature a one-way system. The cells of the capillaries are not tightly joined, instead able to flap open and closed. Fluid from blood capillaries increases pressure. This allows interstitial fluid to enter, until pressure is low enough that they shut.
Specialized lymphatic capillaries that collect fat in the small intestine.
Lacteals.
What is the predominant type of tissue in the lymphatic system, often simply called lymphoid tissue?
Loose connective tissue called reticular tissue that contains specialized cells and thin reticular fibers. The fibers interweave to form nets that trap disease-causing pathogens.
Most lymphoid tissues and organs consist of what main cell types?
Leukocytes, including macrophages, B and T cells. Dendritic cells, which are immune cells with spiny processes. Reticular cells, which produce reticular fibers from thin collagen protein.
What loosely organized clusters of lymphoid tissue protects the mucous membranes? Where is it found?
Mucosa-associated lymphatic tissue, or MALT. Much of it consists of B and T cells. Throughout the gastrointestinal tract, the respiratory passages, and to a limited extent the genitourinary tract.
Specialized MALT consists of roughly spherical clusters called? Most have been exposed to pathogens and so contain what?
Lymphoid follicles, or lymphoid nodules. Those exposed contain light-staining regions, the germinal centers, which consist of dividing B cells, a special kind of dendritic cell, and macrophages.
What specialized clusters of MALT are in the gastrointestinal tract? Where are they located?
Tonsils, around the oral and nasal cavities. Peyer’s patches, or aggregated lymphoid nodules, located in the ileum of the small intestine. Appendix, located off the large intestine.
How are lymph nodes organized physically?
External connective tissue capsule that surrounds a network of reticular fibers. Cortex is lymphoid follicles divided inward by extensions of the capsule, called trabeculae. Between cortex and medulla is a zone of mostly T cells. The medulla has fewer leukocytes but contains mature B cells.
