Ch 3- Immunology and Pathology

Primary function of the immune system
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Terms in this set (111)
Lymphoid stem cellsthymus (lymphoid tissue) produces T-cells (major foot soldiers in the cellular response) or NK lymphocytes (initial non-specific response to an invader to the tissue, release materials to attach pathogens or enhance the immune response) Activated earliest after infectionMyeloid stem cellsstarting point for the production of RBC - produce megakaryocytes, monocytes, granulocytesBone marrowprimary source of production of all blood cells RBC are released into circulation, temporarily stored in the spleen (for maturation)Vaccinationprimes the immune system by giving it a biochemical exposure to an agent that shares enough similarity to something dangerous - Provokes an immune response, trains the system how to deal with viruses similar to the virus of targetAntigen challengedose or inoculation with an antigen given to an animal some time after primary immunization with that antigen has been achievedTransplantationblood transfusions (O-), organ transplants, tissue grafts Tissue transplants carry a set of risks, need to verify that there wasn't any other pathogens or disease pathologyImmune suppressionneed to suppress the immune system to prevent the tissue from being wrecked by immune system Reducing the likelihood of graft rejection: immune system rejecting it or killing the desired tissue being implantedInflammationDefense process of body including congestion of blood vessels, escape of plasma to interstitial tissue space, swelling, and warmth. - Swelling, redness (dilated blood vessels, bringing more WBC) to attack the foreign invader.Asthmainappropriate immune response to pollen or particles within the air - Inflammation of the respiratory tissues - Might need EpiPen, in response to anaphylactic response to allergen -genic: causing something to happenAllergenicgenerating an allergic responsePlasmacarries the cellular components of the bloodRed Blood cells (RBC)erythrocyte, no nuclei, carries oxygenWhite blood cells (WBC)leukocytes (Greek: white cell), have a nucleusPlatelets- Fragments of WBC, initial response to damage of blood vessels. Non-cellular. o Vasoconstriction: narrows the blood vessels to reduce leakingHemostasisto keep blood steady / maintain the blood - Broken ends of blood vessels have to be closed to prevent blood loss. - Platelets become a sticky binding material to seal up the vessels. - Not part of the clotting systemMast cellused to be considered a cell type derived from basophils. We now know they aren't related but function similarly - Produced in the bone marrow On stimulation; release large amounts of histamine (blood dilation, leakiness)DifferentiateTo change into different type (ex. stem cell morphing into RBC)Proliferateto reproduce, increase, or spread rapidly by division (ex. mitosis)Innate (inborn) systemresponse at first exposure. Non-specific, everything foreign will provoke some innate response 1.First line of defence (generalized response, generally is successful) -Stereotyped response, common approach to anything that doesn't belong 2. Response is the same each time pathogen is encountered 3. Common approach to many pathogensInnate system componentsMonocytes/ macrophages Dendritic cells Granulocytes Neutrophils Natural killer cellsAdaptive SystemSPECIFIC. - involves T and B cells, process which started as innate, now have a better idea how to defend Innate immune system has primed the adaptive which can now react better at the next infectionAdaptive system componentsB and T lymphocytesMonocytesAntigen presenting cell (APCs) Phagocytic leukocyte with an oval or U-shaped nucleus. It differentiates into macrophages in various tissues, Kupffer cells in liver, and microglial cells in the central nervous system.Dendritic cellsType of professional antigen presenting cell (APCs) - phagocytic cell, role is to bind to fragments of invading organisms. - Will migrate to the lymph nodes and display the epitopes of antigens on their surface to other cells of the immune response.MacrophageAPC - Important phagocytic cell and antigen-presenting cell, derived from monocyte.GranulocyteEosinophil, Neutrophils, Basophils. Lumpy lobular nuclei - Initial defence against pathogenEosinophiltype of granulocyte that functions in allergic reactions and against parasitesBasophila granular leukocyte, invade cellular tissues and allergic responsesHistamineCytokine; blood vessel dilation, mediates inflammation, increasing blood vessel leaking. Major mediator in allergic responses - Causes: Swelling inflammation, itchiness, Can be problematic; can be highly sensitive to allergens ⟶ Antihistamines: histamine suppressionNeutrophilscritical in the initial destruction of bacterial or viral invaders. Direct disablers of microbial pathogens (viruses and bacteria) - Neutralizing effect on the invasion - Release of granular materials that disables many common pathogens Smaller pathogens are easier to control, larger is more of a challengeNatural killer cellsnon-specific + initial response - secrete chemicals which disable the pathogen or will activate other immediate immune responses - has granules (small particles) with enzymes that can kill tumour cells or cells infected with a virus.LymphocytesBelongs to the Leukocytes, non-granular. Recognition and specific responses - give rise to T and B lymphocytes (produce antibodies) * Mature in lymph nodesB lymphocytes (B cells)type of lymphocyte that gives rise to plasma cells that liberate antibody to the antigenT Lymphocytes (T cells)Type of lymphocyte with a vital regulatory role in immune response. - processed through the thymus. - Subsets of T cells may be stimulatory or inhibitory. - They communicate with other cells by protein hormones called cytokines.Immune responses are mediated by _____cell surface receptors which recognize self vs. non-self, allowing a response to be triggeredCell membrane function- A barrier between outside environment and cell - The binding of antibodies are to surface proteins on the membrane, which may disrupt the parasitic cell membraneSkinMucousCiliaComplementa whole group of small molecules which are generally in circulation, in an infection, they are non-specific, have the function of binding to cell membranes and forming holes. - Immediate disabling, a strong first start attempt to fight pathogen - Chemical weaponsCytokines- Can initiate apoptosis - Activates inflammation: Increases blood flow towards the site of infection (vasodilation) - Extra vascular spaces (Lumen) of the blood vessels - Veins Vasoconstrict; limits blood flow away from an area of injury (maximizes blood flow around the site of infection)TNF-a (Tumor necrosis factor)A cytokine involved in systemic inflammation. - can induce a feverRole of dendritic cells at injury1. Survey the environment 2. Mop up antigen 3. Immature → mature (phagocytic → presenting/communicating) 4. Travels to lymph node to inform T cells NK can secrete IFN-ɑ (interferon) which causesswollen lymphnodeslymphadenopathy: - A rather painful symptom - Plague is transmitted through flea bite. Can infect the lymph node, they grow within them and burst them. Impacting the body's ability to fight them off2 characteristics of the adaptive immune system1. Secondary response is larger than the primary response 2. Immune system has memorySecondary response is larger than the primary response- Focus on the concentration of the antibodies, increase in [antibody] - Second time dealing with pathogen = the body has a game plan (quicker, [antibody] reaches much higher levels) - Vaccine: gives body a slight memory of what the target is, if you end up catching pathogen later, the body can fight harder and fasterImmune system has memory- Can react to the same molecular presentation. Recognizing the memory of first infection, allows them to product high amounts of antibody, and increase T-cell productionHumoral immunity(antibody production) - specific antigen binding sites B CELLSCellular Immunitythe immunity that arises from the activation of T lymphocytes (T cells) by antigen-presenting cells; cell-mediated immunity T CELLSAntibodiesY shaped proteins, made of chains of amino acidsConstant - C(non-changing) portion of antibodyVariable - Vamino acids which make up the V proteins (designated by gene sequences)Antigensparts of something foreign, molecular arrangements never occur naturally within the body (on the cells of the host). The body does have a complementary section on the antibodies (unprimed immune responses; MHC genes)Antigen-antibody complextells the rest of the immune system how to react to the pathogen, contains the memory of the infection. Pathogens have unique molecular sequences, your genes code for receptors within your body which may be a match for the antigenAntibodies are part of the __________ systemHumoral AdaptiveIg (antibody)immunoglobulins; Immune+Globulin: proteins circulating in the blood that stick to thingsIgGImmunoglobulin G (gamma) - Antibody which is most important to the second response (2nd exposure), highly concentrated - Very effective defendersPassive immunityimmune response can be passed onto the fetus. IgG can cross the placenta; the mother can provide a certain amount of immunity. Antibodies were produced by the mother but passed to baby. Baby still has inactive immune systemIgMImmunoglobulin M (mu) - early state of response to pathogen (adaptive response that hasn't been clears by the first innate response)IgAimmunoglobulin A (alpha) - primed system to mucous pathogens, IgA has been produced and can neutralized the pathogens - "Secreted antibody" - High concentrations in mucus, saliva, gut and breastmilk, in the layer of epithelia that line cavities within body - Another way a mother can pass immunity onto her babyIgDImmunoglobulin D (Delta) - Never floats free, it is produced and stays bound by the end of the Y to B-cells. - Captures a circulating antigen: stimulated the B-cell its attached to, and instructs them to produce more antibody - Carried on B cells for activationIgEimmunoglobulin E (episilon) - Evolved as an antibody important in the recognition of worm parasites within the gut - Constant region has a high binding affinity for Mast cells (binds very tightly)Allergic response- B-cells circulate with the receptors of allergens (B cells produce IgE), IgE will bind to mast cells, if the same allergen binds again, the body will release a whole symptomatic response - Initial event: Sensitization ⟶ Secondary event: allergen binds to mast cells, causes the release of histaminesHivesmast cells degranulatingAnaphylactic shockLung tissue starts to swell; oxygen deficiency (anaphylactic shock; extreme response in the airways to the allergen) - most extreme form of allergic responseHygiene HypothesisLack of challenge to the kids' immune systems results in a greater likelihood of intense response to pathogen - Not keeping them in extremely hygienic environments seems to decrease the risk of asthma and severe allergiesMajor Histocompatibility ComplexMHC that present Ags to T cells are HIGHLY variable - The gene set that you inherit (MHC genes are arranged due to what you inherit from parentals) differing resistance to parasites, viral infections, bacterial infections - Recognize self from non-selfGreat Diversity in Recognition of PathogensMany different genes can recombine in a random order to produce Abs (V, D, J, C), and T cell receptors (α and β chains) that recognize many pathogensprimary lymphoid organsthymus and bone marrowThymusB and T cells begin to develop. Produces the initial millions of B-cell clones. Migrate to the lymph nodes and wait to be activatedLymph nodes- normal functioning and diagnosis of infection / abnormal cell division § Painful swelling, location; can diagnose disorderslymphadenopathyswelling of the lymph nodeLymphedemaaccumulation of fluid (lymphatic fluid) within the lymphatic system. Might be an immune response. Symptoms of many parasitic infections.gut associated lymphoid tissueroute through the body that bacteria or parasitic organisms can get into the system § Activated when we ingest a parasiteSpleenis a source of RBC storage which can release mass amount of RBC to restore hematocrit levelsBlood/Lymphatic System- Conduct lymph fluid - Dendritic cells move into the lymph nodes, activated b-cells can move from the lymph nodes to get to the site of infection - Duct between Subclavian vein, connecting the bloodstream and lymph systemsBlood (vascular) and lymph (lymphatic system) moves cells between sites of _____infection to or from lymph nodesLymphatic vesselsKey transport system - Parallel double system of circulation through the lymph nodeLymph node structure- Highly structured for maximum efficiency o Lymphocytes in follicles o Monocytes in medullary areaGerminal centre of lymph nodeFollicles have B cell regions - Un-activated B-cells hang out in the germinal centres, waiting for dendritic activationSurrounding area of lymph nodeFollicles also have T cell regions - T cell zones outside that centerDendritic Cells' bring Ags toT cellsLN swell up when lymphocytes are expanding tofight an infection__________ will produce an antibody to the antigen brought in by the dendritic cellPlasma cellAntigenic material being brought into lymph node (in germinal centers) and rapid proliferation event occurs (big cell population), triggers the swelling in the ____________, jam packed in therelymph nodeAttributes of Parasites Relative to Immune System (4 steps)1. Find niche 2. Gain access to host 3. Avoid host defences 4. MultiplyAntigenic variationHosts can develop adaptive immunity to the malaria parasite (during the erythrocytic cycle). During this replication phase: parasites must find a way to hide from the hosts' immune system - Allows them to go "undercover" - Immune system is 'one step behind'Trypanosoma brucei and antigenic variation§ an array of genes which code for variation and the ability to change the cell surface molecules. Allows the parasite to change their cell surface receptors so that host cells are no longer able to recognize the surface membrane proteins.Why do parasites need to replicate so quickly and plentifully?They must multiply faster than the immune system can fight them offBasal lamina or basement membraneNon-living membrane / layer to which the base of the cells are attached - Can be a tough barrier for parasites to get throughHematophagousblood feedingMosquito carry prostaglandins, which(immunomodulating cytokines: increases blood flow, vasodilator) which increase the blood flow = great for blood suckersHematophagous insect salivaTicks and black flies often produce saliva which itself has evolved as a way of getting past the defences of the hosts (vasoconstriction)The body attempts to restore hemostasis when bitten, by:The body releases Platelets immediately try to plug the hole when vessel is puncturedEvasion of the immune system (4 mechanisms)1. Immune evasion 2. Antigenic variation 3. Apoptosis of immune cells 4. Molecular mimicryImmune evasionInterference with MHC Expression: Decrease expression of recognition/presenting cells (can secrete cytokines to deactivate dendritic cells)Apoptosis of immune cellsparasites can force host cells to undergo apoptosis - Response to intracellular parasites is for host cells to undergo apoptosis of infected cells - Can cause apoptosis of immune cells AND decrease apoptosis of infected cells - Some parasites: have proteins that block apoptosis in cells they infect, and/or proteins that induce apoptosis in immune cells, thus reducing their ability to protectmolecular mimicryo some parasites can look (biochemically) like host tissue o Can absorb circulating host cells, grab on, and pretend like they are host cells o Thereby hiding by looking like host cells and not being seen by the immune systemTwo methods of molecular mimicrya) Absorption of host molecules OR b) have the gene to present host like receptors on their own cellsA functional (competent) immune system is dependent onlow stress and good nutritionPathogen-induced pathogenesis- Physical damage to host tissue due to parasite penetration and wandering, consumption of host tissue - competition for the hosts nutrients - intentionally misdirecting the host immune system