CH 14 LECTURE OUTLINE I. Introduction A. The immune and lymphatic systems protect the body from -pathogens that can produce disease B. Methods of protection 1. If pathogens try to enter the body, they must first get past the barriers, such as intact skin and the secretions of mucous membranes 2. If the pathogen does get into the body, the body recognizes it as not belonging in the body a. This stimulates a series of responses to neutralize the pathogen b. Weapons include special cells and powerful chemicals of the immune and lymph systems c. Other chemicals stimulate inflammatory and clean-up responses C. The combined efforts of the lymphatic and immune systems are required to accomplish this protection II. The Lymphatic System A. The lymphatic system is both the transport system and “barracks” of the immune system B. It works closely with the cardiovascular system C. The lymphatic system has four functions 1. Recycling fluids lost from the cardiovascular system 2. Transporting pathogens to the lymph nodes where they can be destroyed 3. Storage and maturation of some types of white cells 4. Absorption of glycerol and fatty acids from food D. Structures of the lymphatic system (lymph vessels and lymph organs) 1. Lymph capillaries a. Tiny open-ended “pipes” that form a network between cells of connective tissues b. These pipes, which are the smallest in the lymphatic -system, move a fluid called lymph (lymphatic fluid) 2. Lymph capillaries empty into lymphatic vessels, which are similar to veins and have valves a. Body movement and contraction of smooth muscles propel the lymph 3. Large lymphatic vessels empty into lymph nodes a. Many lymph vessels empty into each node b. Lymph nodes are small, encapsulated bodies that can range from the size of a pinhead to the size of an olive i. They act like “filters” for the lymph ii. Inside, the node is divided into sections called -lymphatic sinuses • Each sinus contains white blood cells (WBCs) known as lymphocytes • These WBCs destroy pathogens in the lymph c. Lymph nodes are concentrated in the cervical, axillary, inguinal, pelvic, abdominal, thoracic, and supratrochlear areas i. Adenoids and tonsils, the spleen, and the thymus also contain lymph tissue 4. Lymphatic vessels exiting lymph nodes empty into one of -several lymphatic trunks a. Lymph trunks are named for their location and include the lumbar, intestinal, intercostal, bronchomediastinal, -subclavian, and jugular trunks b. Lymph trunks empty into one of two collecting ducts: i. Thoracic duct • A large duct that runs from the abdomen up through the diaphragm • Empties into the left subclavian vein • Receives lymph from more than two-thirds of the lymphatic system, including - Lumbar trunk - Intestinal trunk - Intercostal trunk ii. Right lymphatic duct • A smaller duct within the right thorax • Empties into the right subclavian vein • Receives lymph from: - Bronchomediastinal trunk - Subclavian trunk - Jugular trunk 5. The lymph ducts empty into the subclavian veins (as noted earlier) a. The thoracic duct empties into the left subclavian vein b. The right lymphatic duct empties into the right subclavian vein 6. The circulation of fluid then follows this pattern, beginning and ending in the bloodstream a. Fluid leaks out of the bloodstream into the tissue b. Tissue fluid goes into lymphatic capillaries c. Lymphatic capillaries carry fluid (lymph) to lymphatic vessels d. Lymphatic vessels carry fluid to lymph nodes e. Lymph nodes filter fluid to remove pathogens; i. Then fluid is delivered to other lymphatic vessels f. Lymphatic vessels carry fluid to lymph trunks g. Lymphatic trunks carry fluid to collecting ducts h. Collecting ducts carry fluid to the subclavian veins, where it reenters the bloodstream 7. Pathology Connection: Tonsillitis a. Tonsillitis i. An inflammation of the tonsils, usually caused by -bacterial or viral infection ii. Symptoms • Sore throat • Swollen tonsils • Fever • Upper respiratory symptoms • Swollen lymph glands • Visible coating or spots on the tonsils • Sometimes upset stomach iii. Diagnosis • Based on the presence of visible tonsil inflammation on physical exam • Throat culture can distinguish between bacterial and viral causes of tonsillitis iv. Treatment • Bacterial tonsillitis must be treated with antibiotics • Viral tonsillitis will resolve on its own • In both types of tonsillitis, symptoms are managed with rest, fluids, and analgesics like Tylenol • Tonsillectomy - Used regularly as a treatment in the past - Today only used if tonsillitis becomes chronic, or if tonsils become enlarged to the point of obstructing the airway 8. Lymph organs—collections of lymphatic tissue (similar to that seen in lymph nodes) located outside the lymph circulation a. Tonsils i. Structures in the throat that contain lymphatic tissue ii. The three sets of tonsils are • Palatine tonsils (located on either side of the orthopharnyx) • Pharyngeal tonsils (known as the adenoids that are located at the posterior of the nasopharynx) • Lingual tonsils (located at the base of the tongue) b. Spleen i. A spongy organ in the upper-left quadrant of the abdomen ii. Structurally similar to lymph nodes but instead of lymphatic sinuses, has blood sinuses • Blood sinuses surround islands of white pulp -containing lymphocytes and islands of red pulp containing both red blood cells (RBCs) and WBCs iii. Functions of the spleen • Removes and destroys old, damaged, or fragile RBCs • Filters pathogens from bloodstream and destroys them iv. Not an essential organ and can be surgically removed if necessary (due to trauma, etc.) • Removal in children can severely compromise immunity but has far less effect on adults v. Because of its rich blood supply, injury to the spleen can cause internal bleeding c. Thymus i. Soft organ located between the aortic arch and sternum ii. Very large in children because of all the new -infections it must handle iii. Gets smaller, but continues to have some activity in adults as the immune system fully matures in its -ability to fight infection iv. Packed with lymphocytes, which mature into a type of WBC called a T-lymphocyte v. Also secretes a hormone (allowing it to also be referred to as an endocrine gland) that stimulates maturation of the T lymphocytes in lymph nodes 9. Pathology Connection: Lymphatic Disorders a. Lymphadenitis i. Disorder of the lymphatic system in which lymph nodes swell • Can affect a small area (localized) or a large area (generalized) • Often caused by a bacterial infection, but may also be the result of viruses, parasites, and fungi ii. Symptoms • Swelling of lymph nodes (initial symptom) • Increased production of white blood cells (initial symptom) • Fever, chills, excessive sweating, rapid pulse, and weakness are more advanced symptoms iii. Treatment • May be treated with infection-specific medication (antibacterial or antiviral medication) • Rest of affected area • Hot moist compresses b. Mononucleosis (“kissing disease”) i. Caused by the Epstein-Barr virus that typically affects children and young adults • Can be spread through oral contact or exchange of saliva • Effects may continue from two weeks to two months after infection ii. Symptoms • Fatigue • Sore throat • Fever • Lymphadenitis • Increase number of lymphocytes iii. Treatment • No specific treatment • Patient is told to get plenty of bed rest • Antibiotics may be prescribed to treat secondary infections c. Hodgkin’s disease (Hodgkin’s lymphoma) i. Rare cancer of the lymphatic system • Characterized by weight loss and itchy skin • Unknown cause, but being a young or older adult, the Epstein- Barr infection, and being a male can contribute to the likelihood of developing the disease ii. Symptoms • Swollen lymph nodes, unexplained fevers, night sweats, and fatigue are early symptoms iii. Treatment • May be treated successfully if caught early with chemotherapy, radiation, or a combination of both 10. Pathology Connection: Cancer Stages and the Lymphatic System a. Cancer staging i. Cancer cells can spread around the body via the -lymphatic system • The degree of spreading can be used to predict a patient’s prognosis - Cancers that have already spread at the time of diagnosis are much more likely to be fatal - The earlier a patient with cancer is diagnosed, the better their chances of beating the disease ii. Stages of cancer (based on degree of spread) • Stage 1—no spread from origin • Stage 2—spread to local tissues • Stage 3—spread to lymph nodes • Stage 4—spread to distant organs (often terminal) III. The Immune System A. The lymphatic system and immune system work together to defend the body against invaders 1. As previously discussed, the lymphatic system is considered the transport system and “barracks” of the body’s defense 2. The immune system provides the weapons and the troops that protect the body from invasion a. It consists of cells, chemicals, and barriers that protect against pathogens b. Some processes are active, some passive, some inborn, and others change with experience B. Antigens and antibodies 1. In order to function, the immune system must be able to -identify which cells are invaders and neutralize them a. Antigens i. Molecules on the outer surface of the cells that -identify them as friend or foe • Each living thing has unique cell surface antigens, allowing the immune system to identify invaders ii. Self- and non-self-recognition are at the heart of how the immune system functions • A well-functioning immune system ignores -self-antigens and attacks non-self-antigens b. Antibodies i. Proteins produced by the body that bind to foreign antigens, eventually destroying them ii. Antibodies are called into action when a foreign -antigen invades the body C. Innate versus adaptive immunity 1. Innate immunity a. Is the body’s inborn ability (a part of our physiology that is not affected by our environment) to fight infection b. Is the front line of defense against invasion i. Prevents invasion, or if the invasion occurs, it takes steps to prevent the spread of infection c.