PET 3323 Summer 2009 Study Guide Exam 3 Lymphatic System 1 Be able to explain the main role of lymph nutrients waste what makes it etc As blood circulates through the body nutrients wastes and gases are exchanged between the blood and the interstitial fluid This fluid plus any plasma proteins that escape from the bloodstream must be carried back to the blood to ensure that the cardiovascular system has sufficient blood volume to operate properly This problem of circulatory dynamics is resolved by the lymphatic vessels or lymphatics which are an elaborate system of drainage vessels that collect excess protein containing interstitial fluid and return it to the bloodstream Once interstitial fluid enters the lymphatics it is called lymph clear water Lymphoid Cells 1 Lymphocytes the 2 Macrophages T and B lymphocytes Protect the body against antigens Phagocytize foreign substances Activate T cells 3 Dendritic Cells Attack antigens Antigen presenting cells 4 Reticular cells Produce reticular fibers 2 Know how lymph drains throughout the body structural anatomy of the lymph capillaries The lymphatic vessels form a one way system in which lymph flows only toward the heart This transport system begins in the lymphatic capillaries Lymphatic capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body They are widespread but they are absent from bones teeth bone marrow and the entire central nervous system They are also remarkably permeable When fluid pressure in the interstitial space is greater than the pressure in the lymphatic capillary the minvalve flaps gape open allowing fluid to enter lymphatic capillary When the pressure is greater inside the lymphatic capillary the minivalve flaps are forced closed preventing lymph from leaking back out as the pressure it along the vessel the moves 3 Know the order of the of the lymphatic circulatory vessels e g capillaries collecting vessels lymphatic trunks lymphatic ducts which regions of the body drained by the ducts and where the ducts empty the lymph fluid back into the blood circulatory system From the lymphatic capillaries lymph flows through succesivly larger and thicker walled channels first collecting vessels then trunks and finally the largest of all the ducts The lymphatic collecting vessels have the same 3 tunics as veins but the collecting vessels are thinner walled and have more internal valves Lymphatics in the skin travel along with superficial veins while the deep lymphatic vessels of the trunk and digestive viscera travel with the deep arteries Lymphatic trunks are formed by the union of the largest collecting vessels and drain fairly large areas of the body Lymph is eventually delivered to one of 2 large ducts in the thoracic region Right lymphatic duct drains lymph from the right upper limb and right side of the head and thorax Thoracic duct receives lymph from the rest of the body Each terminal duct empties its lymph into the venous circulation at the junction of the internal jugular vein and subclavian vein on its own side of the body 4 Know the organs of the lymph system lymph nodes tonsils spleen and their roles Lymph nodes The principle lymphoid organs in the body which cluster along the lymphatic vessels of the body 2 basic functions 1 as lymph is transported back to the blood stream the lymph nodes act as lymph filters Macrophages in the nodes and destroy microorganisms and other debris that enter the loose connective tissues effectively preventing them from to the blood and spreading to other parts of the body 2 the immune system Lymph nodes and other strategically located sites where activated to mount an attack remove lymph from the being delivered They help activate lymphoid organs are lymphocytes encounter antigens and are against them Tonsils Spleen Are the simplest lymphoid organs The tonsils gather and remove many of the pathogens entering the pharynx in food or in inhaled air The lymphoid tissue of the tonsils contains follicles with obvious germinal centers surrounded by diffusely scattered lymphocytes Soft blood rich large lymphoid organ Located in the left side of the abdominal cavity just beneath the diaphragm it curls around the stomach Has blood cleansing functions It extracts aged and defective blood cells and platelets from the blood and its macrophages removes matter from blood flowing through its sinuses debris foreign Thymus Stores some of the breakdown products of red blood cells for later reuse and releases others to the blood for processing by the liver Stores blood platelets It is thought to be a site or erythrocyte production in the fetus Bilobed has important functions primarily during the early years of life Is where T lymphocytes become able to defend us against specific pathogens in the immune response Prominent in newborns and by old age it has been replaced almost entirely by fibrous and fatty tissue and is difficult to distinguish surrounding connective tissue from Mucosa associated lymphatic tissue MALT Peyer s patches Appendix Lymphoid follicles in bronchi Mucosa of genitourinary tissues Immune System defense 5 Know the major components of the immune system e g 1st 2nd and 3rd lines of Functional system made up of two intrinsic defense systems that act independently and cooperatively to provide resistance to disease Innate nonspecific Defense System 1st and 2nd Lines of defense Adaptive specific Defense System 3rd Line of defense 6 Know the primary components of the 1st line of defense The skin and mucous membranes primary components As long as the epidermis is not broken it presents a physical barrier to most microorganisms that swarm on the skin Mucous membranes Protective chemicals secreted 1 acidity of skin secretions pH 3 5 inhibit bacterial growth 2 stomach mucosa secretes HCl and protein digesting enzymes 3 saliva and lacrimal fluid contain lysozymes an enzyme that destroys bacteria 4 mucus traps microorganisms 5 vagina secretions are low pH Skin Keratinized epithelial membrane Resistant to most weak acids bases toxins 7 Know the primary components of the 2nd line of defense i e nonspecific cellular and chemical defenses and their roles in immunity The body uses an enormous number of nonspecific cellular and chemical devices to protect itself including Phagocytes natural killer cells antimicrobial proteins and fever The inflammatory response enlists macrophages mast cells all types of white blood cells and dozens of chemicals that
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