Lymphatic System and Immunity PDF

LYMPHATIC SYSTEM AND IMMUNITY Prepared by: JIAN MIDJ A. OCO, PTRP Presented by: ORIEL M. REPIL, PTRP, MD, OHP OVERVIEW - IMMUNITY IMMUNITY/resistance - is the ability to ward off damage or disease through our defenses. SUSCEPTIBILITY - vulnerability or lack of resistance The two general type...

LYMPHATIC SYSTEM AND IMMUNITY Prepared by: JIAN MIDJ A. OCO, PTRP Presented by: ORIEL M. REPIL, PTRP, MD, OHP OVERVIEW - IMMUNITY IMMUNITY/resistance - is the ability to ward off damage or disease through our defenses. SUSCEPTIBILITY - vulnerability or lack of resistance The two general types of immunity: 1. INNATE (nonspecific) IMMUNITY - refers to defenses that are present at birth. - does not involve specific recognition of a microbe and acts against all microbes in the same way. - components of innate immunity are the first line of defense (the physical and chemical barriers of the skin and mucous membranes) the second line of defense (antimicrobial substances, natural killer cells, phagocytes, inflammation, and fever). Innate Immune Responses - represent immunity’s early warning system and are designed to prevent microbes from entering the body and to help eliminate those that do gain access. OVERVIEW - IMMUNITY 2. ADAPTIVE (specific) IMMUNITY - refers to defenses that involve specific recognition of a microbe once it has breached the innate immunity defenses. - is based on a specific response to a specific microbe; that is, it adapts or adjusts to handle a specific microbe. - involves LYMPHOCYTES (a type of white blood cell) called T lymphocytes (T cells) and B lymphocytes (B cells). OVERVIEW – LYMPHATIC SYSTEM LYMPHOID/LYMPHATIC SYSTEM - contributes to homeostasis by draining interstitial fluid as well as providing the mechanisms for defense against disease LYMPH PLASMA – fluid flowing in the lymph vessel LYMPHATIC VESSELS – vessel that transport the lymph plasma The major difference between interstitial fluid and lymph plasma is location: Interstitial fluid is found between cells, and lymph plasma is located within lymphatic vessels and lymphoid tissue. LYMPHOID TISSUE - is a specialized form of reticular connective tissue that contains large numbers of lymphocytes (agranular white blood cells) LYMPHATIC VESSELS LYMPHATIC CAPILLARIES – where lymphatic vessels begin and is found in the spaces between cells, are closed at one end. – slightly larger in diameter than blood capillaries and have a unique one-way structure that permits interstitial fluid to flow into them but not out. LYMPHATIC VESSELS - resemble small veins in structure but have thinner walls and more valves In the skin, lymphatic vessels lie in the subcutaneous tissue and generally follow the same route as veins lymphatic vessels of the viscera generally follow arteries, forming plexuses (networks) around them. Tissues that lack lymphatic capillaries include avascular tissues (such as cartilage, the epidermis, and the cornea of the eye), portions of the spleen, and red bone marrow. LYMPHATIC VESSELS LYMPHATIC TRUNK AND DUCTS (lymph plasma) LYMPHATIC CAPILLARIES > LYMPHATIC VESSELS > LYMPH NODES As lymphatic vessels exit lymph nodes in a particular region of the body, they unite to form LYMPHATIC TRUNKS: 1. LUMBAR TRUNKS - drain lymph plasma from the lower limbs, the wall and viscera of the pelvis, the kidneys, the suprarenal glands, and the abdominal wall. 2. INTESTINAL TRUNK - drains lymph plasma from the stomach, intestines, pancreas, spleen, and part of the liver. 3. BRONCHOMEDIASTINAL TRUNK – drain lymph plasma from the thoracic wall, lung, and heart. 4. SUBCLAVIAN TRUNK - drain the upper limbs. 5. JUGULAR TRUNK - drain the head and neck. THORACIC DUCT - Receives lymph plasma from the left jugular and left subclavian trunks CISTERNA CHYLI - receives lymph plasma from the right and left lumbar trunks and from the intestinal trunk; Begins in the abdomen LYMPHATIC TRUNK AND DUCTS The lymph plasma passage from the lymphatic trunks to the venous system differs on the right and left sides of the body. On the RIGHT SIDE, the three lymphatic trunks usually open independently into the venous system on the anterior surface of the junction of the internal jugular and subclavian veins 1. RIGHT JUGULAR TRUNK 2. RIGHT SUBCLAVIAN TRUNK 3. RIGHT BRONCHOMEDIASTINAL TRUNK Rarely, the three trunks will join to form a short RIGHT LYMPHATIC DUCT that forms a single junction with the venous system. On the LEFT SIDE of the body, the largest lymph vessel, the THORACIC DUCT forms the main duct for return of lymph plasma to the blood. This long duct, approximately 38–45 cm (15–18 in.), begins as a dilation called the CISTERNA CHYLI anterior to the second lumbar vertebra. THYMUS bilobed organ located in the mediastinum between the sternum and the aorta. It extends from the top of the sternum or the inferior cervical region to the level of the fourth costal cartilages, anterior to the top of the heart and its great vessels high content of lymphoid tissue and a rich blood supply – reddish appearance With age, fatty infiltrations replace the lymphoid tissue – yellowish color LYMPH NODES Around 600 bean-shaped structures around lymphatic vessels scattered throughout the body, 1–25 mm (0.04–1 in.) long Functions as a type of filter, trapping foreign substances and the filtered lymph then leaves the other end of the lymph node LYMPHOID NODULES - are egg-shaped masses of lymphoid tissue TONSILS - masses of lymphoid tissue covered with a mucous membrane. participate in immune responses against inhaled or ingested foreign substances SPLEEN Largest single mass of lymphatic tissue in the body Soft, oval, encapsulated organ of variable size (about 12 cm or 5 in.) located in the left hypochondriac region between the stomach and diaphragm WHITE PULP - carries out immune functions similar to lymph nodes (via phagocytosis) RED PULP - performs three functions related to blood cells: 1. removal by macrophages of ruptured, worn out, or defective blood cells and platelets 2. storage of platelets, up to one-third of the body’s supply 3. production of blood cells (hemopoiesis) during fetal life LYMPHATIC CIRCULATION Lymphatic vessels begin as closed-ended lymphatic capillaries in tissue spaces between cells. Interstitial fluid drains into lymphatic capillaries, thus forming lymph plasma. Lymphatic capillaries merge to form larger vessels, called lymphatic vessels, which convey lymph plasma into and out of lymph nodes. The route of lymph plasma flow is from lymphatic capillaries to lymphatic vessels to lymph trunks to the thoracic duct and right lymphatic duct to the subclavian veins. Lymph plasma flows because of skeletal muscle contractions and respiratory movements. Valves in lymphatic vessels also aid flow of lymph plasma. QUESTIONS