Lymphatic System and Immunity PDF

Unit VIII. Lymphatic System and Immunity https://www.youtube.com/watch?v=cCPyWFK0IKs&t=5s The lymphatic system assists in circulating body fluids and helps defend the body against disease-causing agents. The Lymphatics consists of the following: 1. Lymph – is a clear fluid, similar to...

Unit VIII. Lymphatic System and Immunity https://www.youtube.com/watch?v=cCPyWFK0IKs&t=5s The lymphatic system assists in circulating body fluids and helps defend the body against disease-causing agents. The Lymphatics consists of the following: 1. Lymph – is a clear fluid, similar to both interstitial fluid and blood plasma. Lymph nodes are small structures that work as filters for harmful substances. They contain immune cells that can help fight infection by attacking and destroying germs that are carried in through the lymph fluid. 2. Lymphatic vessels – transport the lymph from interstitial fluid, back into the blood. The lymphatic vessels are thin-walled vessels structured like blood vessels, that carry lymph. Blood vessels also have valves, but only in low pressure venous circulation Valves are found in larger lymph vessels and collecting vessels and are absent in the lymphatic capillaries. The valves is to prevent backflow of fluid, so that lymph eventually flows forward instead off falling backwards. Lymphatic vessels and blood vessels are quite unlike in terms of what they carry (lymphatic fluid vs. blood). Both veins and lymphatics have valves to create directional flow of liquid. 3. Lymphatic tissue – a specialized form of reticular connective tissue that contains large numbers of lymphocytes. 4. Red bone marrow – site where lymphocytes originate (from pluripotent stem cells). Stem cells that can divide into more stem cells or can become any type of cell in the body. 5. Other lymphoid organs 5.1 Spleen. Located on the left side of the abdominal cavity, beneath the diaphragm, and curls around the anterior aspect of the stomach.  In relation to RBC, the “Life Cycle” will be discussed the next slide  https://www.youtube.com/watch?v=cMqwV9Vb4_Y The Life Cycle of the RBC 5 Macrophages in spleen and liver destroy worn out RBCs 6 Hemoglobin is broken down into heme (iron) and globin (protein) 7 Iron from heme returns to the red bone marrow 8 Bilirubin (brownish- yellow) and biliverdin (green pigment excreted in bile 5.2 Thymus gland To protect the body, clearing worn-out red blood cells and other foreign bodies from the bloodstream to help fight off infection. 5.3 Tonsils Traps and removes any bacteria or other foreign pathogens entering the throat.. 5.4 Peyer’s Patches Are small mass of lymphatic tissues found in the ileum of the small intestine. These capture and destroy bacteria, thereby preventing microbes from penetrating the intestinal wall. 5.5 Appendix Contains lymphoid tissue that can destroy bacteria before it breaches the intestine wall during absorption. Functions of the Lymphatic System 1. Fluid removal from interstitial space Interstitial fluid accumulates in the tissues of which the main functions of the LS is to drain the excess fluid to prevent edema. 30 L of fluid pass 27 L pass from the from the blood interstitial spaces back capillaries into the into the blood interstitial spaces capillaries. each day The remaining 3 L fluid enters the lymphatic capillaries, where the fluid is called lymph. If the extra 3 L of interstitial fluid remained in the interstitial spaces, edema would result, causing tissue damage. 2. Fat Digestion and Absorption Fat digestion and The salivary gland Muscle contraction absorption begins slowly releases, lingual lipase, move stomach with some fats melting at an enzymes which has contents, breaking up body temperature in the active role in fat the fat into small pieces mouth. digestion. or droplets. In the LI, bile that is In the SI, the The presence of trapped by dietary fibers gallbladder releases gastric contents (parts of foods the body bile acids with stimulate the release of can't digest or absorb) phospholipids for gastric lipase enzyme exits the body through further emulsification. and fat is digested elimination. 3. Immune cell transport The lymphoid tissues and organs house phagocytic cells and lymphocytes, which play essential roles in body defense and resistance to disease.  Lymphatic capillaries, also called terminal lymphatics, are vessels where interstitial fluid enters the lymphatic system to become lymph. Located in almost every tissue in the body, these vessels are interlaced among the arterioles and venules of the circulatory system in the soft connective tissues of the body. Exceptions are the central nervous system, bone marrow, bones, teeth, and the cornea of the eye, which do not contain lymph vessels. Immunity A state of being protected against microbial invaders by virtue of being able to resist and overcome harmful effects of these invaders." https://www.youtube.com/watch?v=V7sCRjKajZc 1. Humoral immunity (antibody-mediated immune responses 2. Cellular immunity (cell-mediated immune responses) https://www.youtube.com/watch?v=lxC-3MpIMUo Innate immunity are nonspecific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body. I’m first !!!!! Types of antigen 1. relating to or denoting a disease which is not severe enough to present definite or readily observable symptoms. Other types of antigen 2. Class Structure Location Function IgA Dimer Saliva, Protects mucosal tears, milk, surface. and other body secretions Class Structure Location Function IgD Monomer Attached to B cell activation B cell receptors Class Structure Location Function IgE Monomer Secreted When bound to by plasma antigens, binds to cells in skin mast cells and & tissues basophils to lining GIT release histamine and RT that lessen allergic &inflammatory reactions Class Structure Location Function IgG Monomer Blood Most abundant in plasma 1°and 2° immune responses which crosses placenta and provides passive immunity