Lecture 10 Ch21 Lymphatic and Immune F24 post2 PDF

ANATOMY & PHYSIOLOGY Chapter 21 THE LYMPHATIC AND IMMUNE SYSTEM CHAPTER OBJECTIVES After studying this chapter, you will be able to: Identify the components and anatomy of the lymphatic system Discuss the role of the innate immune response against pathogens Describe the power of the ad...

ANATOMY & PHYSIOLOGY Chapter 21 THE LYMPHATIC AND IMMUNE SYSTEM CHAPTER OBJECTIVES After studying this chapter, you will be able to: Identify the components and anatomy of the lymphatic system Discuss the role of the innate immune response against pathogens Describe the power of the adaptive immune response to cure disease Explain immunological deficiencies and over-reactions of the immune system Discuss the role of the immune response in transplantation and cancer Describe the interaction of the immune and lymphatic systems with other body systems  WHAT IS LYMPH? à Interstitial fluid that enters the lymphatic system à From lympha in Latin meaning water à Present in vertebrates à Similar to plasma but lower in protein à Can contain pathogens, debris, etc.  LYMPHATIC SYSTEM à system of collecting vessels, cells, tissues and organs à Functions à carries excess fluids to the bloodstream à filters pathogens from the blood à transports dietary lipids and fat-soluble proteins à passageway for immune cells and gives access to lymph nodes where immune responses develop 21.1 ANATOMY OF THE LYMPHATIC AND IMMUNE SYSTEMS Lymph travels within lymphatic vessels, filters through lymph nodes, empty into the blood via subclavian veins Vessels are closed at one end! Present everywhere in the body except CNS, bone marrow, bones, teeth, and the cornea of the eye All lymphatic vessels carry lymph towards the heart. STRUCTURE OF THE LYMPHATIC SYSTEM Lymph nodes small, bean- shaped organs located throughout the lymphatic system 500-600 Concentrated in cervical, axillary, and inguinal regions  LYMPH NODE FUNCTION Site of immune cell screening of body fluids/blood Site of white blood cell activation Filter lymph (lymph passes through multiple nodes) Enters from afferent vessels & leaves from efferent vessels  LYMPH NODES Site for proliferation of immune cells Swollen near site of infection If all are swollen, systemic infection/disease Metastasizing cancer cells lodge in lymph nodes and begin to multiply à Node swollen but painless, eventually destroyed LYMPHATIC CAPILLARIES start near blood vessels pick up interstitial fluid No pump, just muscular action, valves Endothelial flaps prevent backflow MAJOR TRUNKS AND DUCTS OF THE LYMPHATIC SYSTEM Asymmetrical system of drainage into veins: Right lymphatic duct receives lymph from only the upper right side Thoracic duct receives lymph from all the remaining trunks. THYMUS à Site of T cell maturation à Large in the newborn à Atrophies over time à Also has endocrine function THYMUS IS LARGE AT BIRTH AND SHRINKS AFTER PUBERTY  ADENOIDS Part of the lymphatic system Located behind nasal cavity Not visible through the mouth Start to shrink after age 5  SPLEEN Largest lymphatic organ White pulp: contain WBC have lymphocytes present around splenic arterioles Red pulp: contain WBC and RBC contain macrophages present around sinusoid capillaries Have reticular fibers FUNCTIONS OF THE SPLEEN Removal of old damaged red blood cells “Erythrocyte Graveyard” Protection of the body against foreign invaders (monitored by white pulp) Antigen presentation (Marginal zone between the red pulp and white pulp sequesters particulate antigens from the circulation and presents these antigens to lymphocytes in the white pulp.) Hemopoiesis in fetus Blood reservoir (RBC and platelet storage)  PERIPHERAL EDEMA Peripheral edema is defined as tissue swelling that occurs when lymphatic vessels are unable to drain excess interstitial fluid. CAUSES OF PERIPHERAL EDEMA Damage to lymph nodes (due to surgery) Blockage of lymphatic vessels (due to cancer) Damage to lymph nodes (due to cancer treatments) Infection of lymph nodes (due to infectious organism)  SIGNS, AND DIAGNOSIS AND TREATMENT Other signs and symptoms Restricted range of motion Recurring infections Discomfort and aching Skin feels tight and may thicken diagnosed by physical examination, MRI, CT scans or u/s Treatment: diuretics to expel excess fluid. Furosemide: a medication that acts on the kidneys to promote water loss through urine THE IMMUNE SYSTEM à protects the body by preventing attacks from certain microorganisms, known as pathogens, and the chemicals and toxins that they release. A pathogen is any organism that can cause disease in a host, examples: bacteria, protozoa, fungi, and helminths (worms) Two parts with overlapping functions: 1.) Innate immune system (barriers, chemicals and WBC) rapid but nonspecific and thus not always effective Its response does not change with subsequent exposures 2.) Adaptive immune system (WBC: B and T cells) slower during an initial infection but highly specific and effective at attacking a wide variety of pathogens, has “memory” ALL BLOOD CELLS ARE MADE FROM HEMATOPOIETIC STEM CELLS AT THE BONE MARROW Cells of the Innate Cells of the Adaptive Immune System Immune System CELLS OF INNATE AND ADAPTIVE IMMUNITY INNATE IMMUNITY ADAPTIVE IMMUNITY INNATE IMMUNITY INNATE IMMUNE SYSTEM CELLS AND MECHANISMS OF ACTION  Neutrophils Granular phagocytosing cells, most common First responders at bacterial infection 1. Phagocytosis: engulf bacteria 2. Degranulation: release lysozyme, oxidants and defensins 3. NET release: neutrophil extracellular traps (NETs) trap invaders  Eosinophils Granular phagocytosing cells First responders at parasitic infection and allergy response 1. Phagocytosis: engulf parasitic worms (better when antibody is attached) 2. Degranulation: release antihistamines (limit inflammatory response of basophils)  Basophils Granular cells Least common WBC Involved in allergy response Degranulation: release histamines (enhance allergic inflammatory response), heparin (prevent blood clotting)  Macrophages Phagocytotic cells for foreign pathogens, worn-out erythrocytes, and damaged cells. Can be resident to tissue or in blood Release antimicrobial defensins and chemotactic chemicals that attract other leukocytes to the site of an infection Defense against viral or fungal infections Uptake antigen-antibody complexes Form foam cells in plaque DEFENSINS POKE HOLES IN PATHOGEN MEMBRANES A phagocytic WBC engulfing a yeast cell  Natural Killer (NK) Cells - Destroy “non-self” cells (cancer cells, cells infected with a virus, other cells with atypical surface proteins) - Release granzymes and perforins Part of the Innate Immune System ANTIMICROBIAL PROTEINS: COMPLEMENT SYSTEM: Circulate in the blood until activated by presence of the pathogen Support immune response in 4 ways: Inflammation Immune clearance Phagocytosis Cytolysis Can stimulate immune cells, bind and tag pathogens, bind and lyse pathogenic organisms Part of the Innate and Adaptive Immune System ANTIMICROBIAL CHEMICALS A variety of proteins produced by the innate immune system can also kill pathogens: Defensins: peptides kill foreign cells by poking holes in the cell membrane or cell wall of the pathogen. Cytokines, chemokines and interferons: secreted signaling molecules that help regulate both the innate and adaptive immune systems and their responses INFLAMMATION Damage, injury, trauma, or infection causes inflammation Inflammation: innate immune system’s localized response to cellular injury. Function is à to prevent spread of microorganisms à initiate tissue repair CENGAGE FOUR CARDINAL SIGNS OF INFLAMMATION 1. Redness 2. Heat 3. Swelling 4. Pain CENGAGE INFLAMMATION Redness, swelling, heat, pain INFLAMMATION OVERVIEW FEVER AKA pyrexia Abnormal elevation in body temperature > 98.6°F (37°C) Pyrogens – fever-producing agents Paramount Pictures Exogenous – from bacteria or viruses Endogenous – secreted by neutrophils and macrophages Stimulate hypothalamus to raise body temperature set point Antipyretics prevent this Adapted from BIOL2219 S22 STAGES OF FEVER 1) Onset Hypothalamic temperature set point raises Body shivers to generate heat Cutaneous arteries constrict to retain heat 2) Stadium Body temperature oscillates around higher set point Increased body temperature: Promotes interferon activity Inhibits reproduction of bacteria and viruses Elevates metabolic rate and accelerates tissue repair 3) Defervescence Hypothalamic thermostat resets to baseline Cutaneous vasodilation and sweating release heat COOPERATION BETWEEN INNATE AND ADAPTIVE IMMUNE RESPONSES Cells of the Innate and Adaptive Immune System Work Together! T cells, B cells, NK cells T cells and memory T cells à adaptive immune response, destroy infected or cancerous cells, B cells à Plasma cells and memory B cells à adaptive immune response, secrete antibodies and provide immune memory NK cells à kill viruses and certain types of cancer by releasing cytotoxic granules Antigen-presenting cells (APCs) Macrophages, dendritic cells à kill invaders, activate other immune cells Reticular cells à support structure of lymphatic tissues