13. immune system

non specific chemical and physical barrier to infection and pathogen

respond to presence of pathogens in body

response consisting of phagocytosis and inflammation

cell-mediated response with t lymphocytes and humeral response with antibodies

a defence containing enzyme lysozyme which digests walls os bacteria if they enter conjunctiva

defence mechanism where the area is repaired with a blood clot

sticky substance which traps pathogens which are then moved by rhythmic beating to the throat to be swallowed

hydrochloric acid denatures pathogens enzymes

unbroken barrier with compacted cells impregnated with insoluble fibrous protein, keratin

acidic conditions denature pathogens enzymes

neutrophils and monocytes in blood and macrophages in tissues are responsible for non specific response acting ac phagocytes and engulf pathogens

circulate in blood developing into macrophages in tissues

longer lived than neutrophils, engulf and digest many pathogens, lymph nodes, act as antigen presenting cells so initiates specific immune response

travel in blood, able to squeeze through capillary wall to reach pathogens in tissues

tissue around infection or wound becomes swollen, red and hot

produced by mast cells to attract neutrophils by chemotaxis, causes vasodilation, more tissue fluid formed

released by damaged cells, these attract phagocytes to the area

1. lysosomes fuse with phagosomes to form phagolysosome, the pathogen is then destroyed by the release of lysins, hydrolytic enzymes

2. phagocyte attaches to pathogen by having complementary receptors to opsonins

3. opinions coat pathogen surface

4. phagocytes engulf pathogen by endocytosis forming a phagosome

5. soluble products of hydrolysis are absorbed into cytoplasm eg amino acids, glycerol and sugars

6. indigestible and unwanted products removed by exocytosis

caused by macrophages engulfing and digesting the pathogen, it then displays the antigens on its surface

molecules that stimulate an immune response, often proteins or glycoproteins at cell surface

immunoglobulins which are glycoproteins that bind and neutralise affects of antigen, produced by b lymphocytes

white blood cell which matures in bone barrow, differentiates to produce specific antibodies

white blood cell which matures in thymus, it identifies and destroys infected cells

undergone when a cell recognises a self antigen to prevent an autoimmune response

lymphocytes with complementary receptor are selected

lymphocytes divide by mitosis to produce identical specific cells

originate from b lymphocytes these cells synthesis antibodies

remain in body for some years providing immunological memory, produce plasma and memory cells

attach and kill infected body and cancer cells by secreting cytotoxins

depress the immune cells one pathogen been destroyed

remain in body for some years produce killer cells, helper cells, regulatory cells, regulatory cells and memory cells as part of secondary response

1. complementary B lymphocytes to foreign antigen are activate day clonal selection divide by mitosis clonal expansion

2. t helper cells stimulate b lymphocytes by cytokines

3. phagocyte presents foreign antigen on surface

4. t lymphocytes divide by mitosis, clonal expansion and differentiate into t helper cells, t killer cells, t memory cells, and t regulatory cells

5. phagocyte like a macrophage engulfs and digest pathogen

6. activated b lymphocytes differentiate into b memory and plasma cells which secrete antibodies

7. phagocytes activate t lymphocytes with complementary receptors to foreign antigen

extensive Golgi apparatus for modification of antibodies (add carbohydrates and pack into vesicles)

many mitochondria provide ATP for synthesis and secretion of antibodies

extensive rough endoplasmic reticulum for antibody production

large nucleus for gene transcription of antibodies

large nucleolus for production of ribosomes

memory cells are already in blood and are able to rapid differentiate in to many plasma cells so eliminate infection before person feels ill

molecule made up of light and heavy chains, with a constant and variable region held by a hinge region

holds chains together on antibodies

forms complementary antigen binding site different amino acid sequence for each antibody

main body of antigen which attaches to cell membrane of phagocyte

allows molecule to flex so can bind to antigens on different pathogens

neutralisation, agglutination, precipitation which enhance phagocytosis

activation of complement system which leads to cell lysis

large antibody binds multiple pathogens together so can’t infect cells and are engulfed by phagocyte

antibodies bind to antigen on surface of pathogen preventing it binding to target cell and clocks toxin activity

antibodies bind to antigens which activates proteins on surface to form pores on bacterial cell membrane

antibodies bind to antigens, phagocyte as a receptor for content region of antibody, facilitates attachment of pathogen to phagocyte for engulfing by phagocytosis

yes ro test for hypersensitivity to TB antigens, used before wether BCG vaccination needed, only used to test for people at high risk

1. inflammation occurs at site within 72 hours producing red raised swelling (positive)

2. if person has had TB before immune response will be triggered

3. weak or no response indicates vaccination needed (negative)

4. tuberculin is injected underskin

induration which is considered positive in HIV infected persons, recent counted with TB, immunosuppressed persons

induration is considered positive if doing intravenous drugs, recent immigration from TB prevalent area, infants and children under 4

induration considered positive in anyone

uses finger prick or mouth swab, immuoblot assay detects antibodies, 20-30 mins, low sensitivity

alternative test for HIV, detected presence of antibodies and p24 antigen using ELISA, higher sensitivity, detects 14-42 days after infection

when a test incorrectly indicates a substance Is present

when a test incorrectly indicates a substance is not there

HIV antigen that is present in high concentration after the first few weeks of infection

test used to detect specific antigens or antibodies by having a complementary compound with a an enzyme which causes a colour change with a substrate

produced when body causes a immune response to a pathogen or vaccination, long term

person receives antibodies offering temporary protection, eventually antibodies broken down

maternal antibodies from placenta or breast milk, lasts as few months

when a person receives antibodies via injection

when immune system responds to an antigen that is non pathogenic, inflammatory

1. more allergens inhaled which attach to antibodies / lgE on mast cells

2. triggers inflammatory response. rhinitis symptoms, itchy and watery eyes

3. allergen causes antibody / lgE production

4. antibody attaches to mast cells sensitising person to allergen

5. mast cells triggered to release histamine as part of degranulation to remove antigen

inflammation of inside of nose caused by allergen

any undesirable reaction produced by immune system, including allergic reaction and autoimmune response, only when host is already sensitise to allergen