Immune Response PDF

Immune System Immune System 1 Compose of a complex collection of cells, tissues and organs that work together defending the body 2 Must cope with invading organisms • Pathogens, substances, abnormal cells 3 Must be able to distinguish “self” from “non self” with a high degree of accuracy. A stro...

Immune System Immune System 1 Compose of a complex collection of cells, tissues and organs that work together defending the body 2 Must cope with invading organisms • Pathogens, substances, abnormal cells 3 Must be able to distinguish “self” from “non self” with a high degree of accuracy. A strong immune system is crucial for maintaining overall health and wellbeing It helps prevent infections, promotes quick recovery, and plays a role in disease prevention Immune System • Immunity refers to protection against infection • The coordinated reaction of the immune system against infections (and other foreign substances) is known as the immune response Lymphatic Organs Primary Red bone marrow Thymus gland Secondary Lymph nodes Spleen Thymus gland • The thymus is a superior mediastinal retrosternal organ • It is bilobed and has two subcomponents: the cortex and the medulla • is made up of epithelial, dendritic, mesenchymal, and endothelial cell • Form WBC called T lymphocytes until adolescence, help to fight infections Immune System Designed to defend the body against foreign or dangerous invaders: • Microorganism • Bacteria, viruses, fungi, parasites • Cancer cells • Transplanted organs and tissues Lymph nodes 2 3 • Lymph nodes are kidney-shaped and receive lymph via multiple afferent vessels, and filtered lymph then leaves via one or two efferent vessels 1 4 • function of lymph nodes is filtering interstitial fluid collected from soft tissues and eventually returning it to the vascular system 5 • Filtering this exudative fluid allows for exposure of T-cells and B-cells to a wide range of antigens Spleen • The spleen controls the level of white blood cells, red blood cells and platelets • removes old or damaged red blood cells • If the spleen doesn't work properly, it may start to remove healthy blood cells Immune Response Innate Immune System Adaptive immune System Physical barriers Cellular Immunity Phagocytes Humoral Immunity Complement System Innate Immune Response • Feverishly Fast • Within minutes • No memory of the previous pathogens • defenses are not directed against any one pathogen but instead, provide a guard against all infection Innate Immune System External (First line) defense Physical barriers Epidermis of skin – acts as a barrier Mucous membranes – acts as a barrier Mucous secretion from ciliated epithelium – trap pathogens Tears – lysozymes Saliva -lysozymes Urine Defecation and vomiting Chemical barriers Sebum Lysozymes Gastric juice – acids Vaginal secretions Innate Immune System Internal (secondary line) defense If a pathogen is able to get past the first line of defense, causes an inflammatory response (redness, heat, swelling, pain) Recognizes an invading organism Phagocytes PMN’S, Macrophages Complement system Phagocytosis 1 CHEMOTAXIS 1 CHEMOTAXIS Microbe Phagocyte 2 ADHERENCE 2 ADHERENCE 3 INGESTION INGESTION Pseudopod Pseudopod Lysosome Lysosome Plasma Plasma membrane membrane DIGESTION 4 DIGESTION Digested microbe in phagolysosome 5 KILLING Digestive Digestive enzymes enzymes Phases of phagocytosis Phases of of phagocytosis phagocytosis Phases Residual body (indigestible material) Functions of the complement system: (1) the activation of inflammation (2) the opsonization of pathogens and cells for clearance/destruction (3) the direct killing of target cells/microbes by lysis C3 C3 11 22 C3b C3b C3b C3a C3a C3a Histamine Histamine C5 C5 33 C5b C5b 4 PHAGOCYTOSIS: PHAGOCYTOSIS: nhancement of phag ocytosis C7 Enhancement phagocytosis yycoating of with C3b By coating with C3b MMicicrorobbee C5a C5a C6 Mastcell cell Mast INFLAMMATION: INFLAMMATION: Increaseof bloodvessel vessel ofblood blood vessel Increase permeabilityand chemotactic andchemotactic chemota permeability attractionof ofphagocytes phagocytes attraction C8 C9 C5b C6 C7 C8 C3b Opsonization Phagocytosis C9 Channel Membrane attack complex forms channel Microbial plasma membrane CYTOLYSIS: Bursting of microbe due to inflow of extracellular fluid through channel formed by membrane attack complex C5-C9 C5b Chemotaxis Complement System • Two pathways • Classical • Triggered by directly by a pathogen • Alternative • Triggered by C3b • Opsonize and kill pathogens Adaptative Immune Response • Is activated when pathogens are able to bypass innate immune defense • Cells that belong in the body carry specific markers that identify them as "self" and tell the immune system not to attack them • Once the immune system recognizes a pathogen as "non-self," it uses cellular and chemical defenses to attack it • After an encounter with a new pathogen, the adaptive immune system often "remembers" the pathogen, allowing for a faster response if the pathogen ever attacks again Antigens • substances that recognize a pathogens and stimulate an immune response • Normally found in the surface of pathogens (unique) • The immune system respond producing Antibodies • Antibodies attach to the antigen to destroy the pathogen Immune Response • Cells that are activated by antibodies are • Lymphocytes (produced in the bone marrow) • B cells • T cells Immune complex = antigen-antibody complex Humoral immunity • Actions of antibodies circulating through the body • Begins when an antibody on a B cell binds to an antigen • The B cell then internalizes the antigen and presents it to a specialized helper T cell, which in turn activates the B cell • Activated B cells grow rapidly, producing plasma cells, which release antibodies into the bloodstream • Memory B cells, which store information about the pathogen in order to provide future immunity Cell mediated immunity • Antibodies alone are often not enough to protect the body against pathogens • the immune system uses cellmediated immunity to destroy infected body cells • T cells are responsible for cellmediated immunity • Killer T cells (cytotoxic T cells) assist with the elimination of infected body cells by releasing toxins into them and promoting apoptosis • Helper T cells act to activate other immune cells Antibody Composed of 4 chains 2 heavy 2 light Heavy chains 5 isotypes  alpha  delta  epsilon  gamma  mu Light chains  kappa IgA  lambda IgD IgE IgG IgM Antibody Each chain is composed of 2 regions 1 variable (V) 1 constant (C) Disorders of the Immune System • The body generates an immune response against itself - an autoimmune disorder • The body cannot generate appropriate immune responses against invading microorganisms an immunodeficiency disorder • The body generates an excessive immune response to often harmless foreign antigens and damages normal tissues -an allergic reaction Vaccines • Vaccines work by taking advantage of antigen recognition and the antibody response • vaccine contains the antigens of a pathogen that causes disease Term Meaning Pathogen A disease-causing organism, including bacteria, Antigen Molecule that stimulates an immune response Innate immune system Non-specific immune system Adaptive immune system Antigen-specific immune system Antibody Specialized Y-shaped protein that tags antigens for destruction B cells White blood cells that produce antibodies and aid in immunological memory T cells White blood cells specialized to assist B cells (helper T) and others directly kills infected cells (killer T) Humoral immunity Adaptive immune defense depending on the action of antibodies Cell-mediated Immunity Adaptive immune defense in which foreign cells are destroyed by T cells