Chapter 21 Immune System
2nd line of defense is internal defenses: CELLS and CHEMICALS 1. Phagocytes "self eating" must recognize carbohydrate signature to adhere and destroy. *problem is Bacteria may be within capsules that hide the signature How does are immune system get around the problem of bacteria capsules hiding the signature carb? -by coating pathogens with OPSONINS. OPSONINS- complement proteins or antibodies marks pathogen for phagocytes to recognize and eat up OPONIZATION-To make tasty "coating a pathogen with opsonins.
LYMPHOCYTE MATURATION: 1. T CELLS migrate in the blood to mature in THYMUS 2. B CELLS mature in the Bone Marrow. Lymphocytes Mature by: 1. becoming immunocompetent 2. Self-Tolerance 1.Immunocompetent is the ability for the lymphocyte to recognize its "ONE" specific antigen by binding with it! *When B & T cells become immunocompetent they display a unique type of receptor on their surface 2. Self-Tolerance is when the B or T Lymphocytes become unresponsive to self-antigens so that it does not attack the body's own cells.
2nd line of defense is internal defenses: INNATE INTERNAL CELLS and CHEMICAL DEFENSES GUARDS THAT CHK ID ALWAYS READY TO ATTACK! 1.-Phagocytes 2.-NKC 3.-Antimicrobial proteins 4.-Fever 5.-****Inflammation***
LYMPHOCYTE ORGIN & DEVELOPEMNT: BOTH B & T CELLS PRECURORS ORIGINATE IN? RED BONE MARROW FROM HEMATOPOEITC STEM CELL
INTERFERONS have an indirect role in fighting cancer. because IFN ACTIVATEs: both Macrophages and NK cells can also act DIRECTLY against cancerous cells.
Passive Humoral immunity differs from active immunity in 2 ways: 1. antibody source 2. degree of protection
INTERFERON- are a class of CYTOKINES -made by cell when it realizes its been infected with a VIRUS. -Virus infected cells help protect neighboring healthy cells -IFN interferes with VIRAL REPLICATION by producing a protein PKR which interferes with protein synthesis and degrading viral RNA. -IFN protection is NOT VIRUS SPECIFIC it can protect against other viruses too.
Passive immunity: -instead of being made by your own plasma cells, ready-made antibodies are introduced into your body -temporary yet immediate protection -short lived only 2-3 wks -no memory *anitbodies introduced to the system via: 1. artificially acquired- Exogenous antibodies ex. -injections gamma globulin -hep A -snake bite antivenom -botulism -rabies -tetnus 2. Naturally acquired- breast milk
4. FEVER-abnormally high body temp -Systemic response to more widespread invasion of microbes Pyrogens- are chemicals that act on the hypothalamus the body thermostat rising the body temp above normal. triggered when leukocytes and macrophages are exposes to foreign substances. Pyrogen cause the fever Fever- increases metabolism and HR may speed up repair process
STRUCTURE OF AN ANTIBODY: 2 LONG HEAVY CHAINS (identical to each other) 2 SHORT LIGHT CHAINS (identical to each other) Held together by disulfide sulfur-to-sulfur bonds The 4 chains combined is called an antibody monomer The molecule as a whole is either Y or T shaped Each chain forming antibody has a (V) variable region and a (C) constant region at the end The Variable V-region of the heavy and light chains combine to form an antigen binding site shaped to fit a specific antigenic determinant. *each antibody monomer has 2 antigen binding binding regions C region forms the "STEM" of the antibody monomer and determine the antibody class and FNS. 2 FNS: 1. what cells and chemicals the antibody can bind to. 2. how the antibody class fns to eliminate antigens
3. ANTIMICROBIAL SUBSTANCES:- enhance our innate defenses by attacking microbes directly or hindering invaders reproduction
2 TYPES OF HUMORAL IMMUNITY: 1. Active Immunity 2. Passive Immunity
1. INNATE DEFENSES (quick) *always ready and on!
2. ADAPTIVE DEFENSES (slow, due to priming) *must "meet" or be primed by initial exposure to a antigen
2nd line of defense is internal defenses: CELLS and CHEMICALS -Phagocytes -NKC -Antimicrobial proteins -Fever -****Inflammation***
3rd line of defense is the Adaptive Defenses ANTIGENS identified by ......Lymphocytes and APC's trigger 2 responses: 1. Humoral Immune response (B Cells) 2. Cellular Immune response (T Cells)
5. INFLAMMATION RESPONSE - localized response to infection and goal is to prevent spreading to nearby tissues -Triggered when tissues are injured by: tramua, heat, chemicals, infection by viruses, bacteria or fungi Benefits of inflammation: 1. prevents the spread of damaging agents to nearby tissues 2.disposes cell debris and pathogens 3. alerts ADAPTIVE IMMUNE system 4. sets the stage for repair The inflammatory process begins with a chemical alarm! Examples of inflammatory chemicals are: 1.HISTAIMNE-caues swelling by exudate increase permeability of local capillaries and vasodilates Histamine is produced by MAST CELLS, a "KEY Component" to the inflammatory response. 2. Kinins -induce pain/neutraphil chemotaxis 3. Prostaglandins -induce pain/neutraphil chemotaxis 4.COMPLEMENT 5. Cytokines *all inflammatory chemicals: dilate local arterioles (Redness and Heat) HYPEREMIA and make capillaries leakier (Swelling, edema caused by Exudate) -Many attract LEUKOCYTES to the injured area Inflammatory Chemicals cause: 1. Heat-Vasodilation 2. Redness-Vasodilation 3. Swelling --Increase Capillary Permeability 4. Pain-Increase Capillary Permeability swelling presses on nerve endings or can be a result of bacterial toxins and the sensitizing effects of prostaglandins and kinins.
5 Major Immunoglobulin classes of antibodies: "MADGE" 1. IgM- First Ig class secreted by plasma cells during primary response. - Fixes & Activates Complement. -shape is a pentamer snowflake or 5 united monomer forms -numerous binding sites make it a potent agglutinating agent 2. IgA- found in body secretions such as saliva, sweat, intestinal juice and milk. -helps stop pathogens from attaching to endothelial cell surfaces including mucous membranes and epidermis. -Shape is a Dimer but the monomer exists in limited amounts in plasma. 3. IgD- found on the B cell surface -Fns as a B cell antigen receptor like IgM -Shape monomer 4. IgG- most abundant antibody in plasma"think G for Greater" -Main antibody of both secondary and primary responses. -readily fixes and activates complement -protects against: bacteria, viruses, toxins in blood and lymph -crosses placate and gives passive immunity to fetus 5. IgE- Least abundant "think e for end" <.1%in blood. -stem end minds to mast cells or basophils. triggers theses cells to release histamine and other chemicals that mediate inflammation and allergic reaction. -levels rise during severe allergic reactions or parasitic infections of the GI tract -Secreted by plasma cells in skin, muscosae of GI, respiratory tract and tonsils.
1st line of defense is the surface barriers: -SKIN and MUCOUS MEMBRANES
ADAPTIVE IMMUNE RESP0NSE IS: 1. Specific-Recognizes and targets specific pathogens 2. Systemic-not restricted to infection site 3. Has Memory-after 1st exposure has antibodies ready
Genetically engineered Interferons are used to treat: 1. Hep c 2. genital warts 3. multiple sclerosis
ANTIBODIES AKA... IMMUNOGLOBULINS (Igs) -Are proteins secreted in response to an antigen by PLASMA Cells.
Rapid ways to expel microbes: 1. Vomiting 2. Diarrhea
ANTIBODIES DO NOT KILL ANTIGENS DIRECTLY INSTEAD THEY "INACTIVATE" ANTIGENS AND TAG THEM FOR DESTRUCTION!
ANTIMICROBIAL SUBSTANCEs include: -Interferons -complement
Active immunity: Body makes own plasma made antibodies when B cells encounter antigens and produce antibodies against them. achieved 2 ways: 1. Naturally acquired -Infection contact with Pathogen 2. Artificially acquired -vaccine for disease *have memory
Innate Defenses are NONSPECIFIC defenses
Adaptive Defenses are SPECIFIC defenses
soon after inflammation begins phagocytes flood the damaged area. Neutrophils are 1st to arrive then macrophages. If pathogens provoke inflammation compliment is activated and elements of the Adaptive Immune System arrive (lymphocytes and antibodies) 4 steps to INFLAMMATION PHAGOCOTYE MOBILIZATION STEPS: 1. Leukocytosis-increase in WBC Neutrophils 2. Margination (CAM) cell adhesion molecules say this is the place and neutrophils stop and roll, cling to capillary wall 3. Diapedesis-Neutrophil flatten and squeeze out of capillary 4. Chemotaxis-Neutrophils follow chemical trail, stop spread of infection and clears debris
B cells switch from making one class of antibody to another as they become plasma cells. primary response=IgM secondary response=almost all Ig is switched to IgG
1st line of defense the SKIN & MUCOUS MEMBRANES : EXTERNAL DEFENSES /SURFACE BARRIERS THINK CASTLE! SKIN -heavily KERATINIZED epidermis resistant to weak acids and bases and to bacterial enzymes and toxins *besides serving as physical barriers both skin and mucous membranes produce protective chemicals: 1. ACID- acidity of skin, vagina, stomach inhibit bacterial growth 2. Enzymes- (lysozyme) found in Saliva, Tears & Respiratory mucus destroy bacteria 3. MUCIN-thick sticky mucus traps bacteria 4. Defensins-animicrobial peptides helps control bacteria and fungus 5. Other CHEMICALS: Sebum
CELLS OF THE ADAPTIVE IMMUNE SYSTEM: 1. B-Lymphocytes-humoral immunity do not destroy things directly 2. T-Lymphocytes- cellular immunity (non-antibody producing) attack directly and lyse the cells 3. APCs or antigen presenting cells- introduce T-Cells to antigen examples of APCs are: dendritic cells B cells macrophages
Active phagocytes are: 1.Neutrophils -most abundant 1st on scene -can carry out Respiratory Bursts to kill bacteria a release of oxidizing bleaching chemicals "pus" to destroy itself and invader only does this when overwhelmed . -Neutrophils also use Defensisns or peptide spears that pierce holes in pathogens membrane and ingest microbe 2.Macrophages (derive from Monocytes) "big eaters" -Destroy VIRUSES and intercellular bacterial PARASITES -Activate Immune System 2 kinds of Macrophages: 1. Free -move and wander throughout tissue spaces searching for cellular debris and invaders. Ex.-Aveolar macrophages or dendritic cells 2. Fixed- ex. Stellate macrophages (Kupfter cells) found in liver , microglia 3.EOSINOPHILS -sign of allergies/lessen severity of allergies by phagocytizing immune complexes digest parasitic worms
Humoral vs Cellular immunity Humoral: -do not destroy things directly -memory cells B cells-----Plasma cells-----produce antibodies *antibodies cannot kill antigens directly they can inactivate antigens and tag them for destruction. Cell Mediated Immunity: APC cells need to introduce T-cells to antigens -T cells attack and kill directly