primary defences
non specific chemical and physical barrier to infection and pathogen
secondary defences
respond to presence of pathogens in body
non specific response
response consisting of phagocytosis and inflammation
specific immune response
cell-mediated response with t lymphocytes and humeral response with antibodies
tear ducts
a defence containing enzyme lysozyme which digests walls os bacteria if they enter conjunctiva
broken skin
defence mechanism where the area is repaired with a blood clot
mucus and cilia
sticky substance which traps pathogens which are then moved by rhythmic beating to the throat to be swallowed
stomach
hydrochloric acid denatures pathogens enzymes
skin
unbroken barrier with compacted cells impregnated with insoluble fibrous protein, keratin
vagina
acidic conditions denature pathogens enzymes
leucocytes
neutrophils and monocytes in blood and macrophages in tissues are responsible for non specific response acting ac phagocytes and engulf pathogens
monocyte
circulate in blood developing into macrophages in tissues
macrophages
longer lived than neutrophils, engulf and digest many pathogens, lymph nodes, act as antigen presenting cells so initiates specific immune response
neutrophil
travel in blood, able to squeeze through capillary wall to reach pathogens in tissues
inflammation
tissue around infection or wound becomes swollen, red and hot
histamine
produced by mast cells to attract neutrophils by chemotaxis, causes vasodilation, more tissue fluid formed
cytokines
released by damaged cells, these attract phagocytes to the area
3, 2, 4, 1, 5, 6,
lysosomes fuse with phagosomes to form phagolysosome, the pathogen is then destroyed by the release of lysins, hydrolytic enzymes
phagocyte attaches to pathogen by having complementary receptors to opsonins
opinions coat pathogen surface
phagocytes engulf pathogen by endocytosis forming a phagosome
soluble products of hydrolysis are absorbed into cytoplasm eg amino acids, glycerol and sugars
indigestible and unwanted products removed by exocytosis
antigen presenting cells
caused by macrophages engulfing and digesting the pathogen, it then displays the antigens on its surface
antigens
molecules that stimulate an immune response, often proteins or glycoproteins at cell surface
antibodies
immunoglobulins which are glycoproteins that bind and neutralise affects of antigen, produced by b lymphocytes
b lymphocyte
white blood cell which matures in bone barrow, differentiates to produce specific antibodies
t lymphocyte
white blood cell which matures in thymus, it identifies and destroys infected cells
apoptosis
undergone when a cell recognises a self antigen to prevent an autoimmune response
clonal selection
lymphocytes with complementary receptor are selected
clonal expansion
lymphocytes divide by mitosis to produce identical specific cells
plasma cells
originate from b lymphocytes these cells synthesis antibodies
B memory cells
remain in body for some years providing immunological memory, produce plasma and memory cells
t helper cells
attach and kill infected body and cancer cells by secreting cytotoxins
t regulatory cells
depress the immune cells one pathogen been destroyed
t memory cells
remain in body for some years produce killer cells, helper cells, regulatory cells, regulatory cells and memory cells as part of secondary response
complementary B lymphocytes to foreign antigen are activate day clonal selection divide by mitosis clonal expansion
t helper cells stimulate b lymphocytes by cytokines
phagocyte presents foreign antigen on surface
t lymphocytes divide by mitosis, clonal expansion and differentiate into t helper cells, t killer cells, t memory cells, and t regulatory cells
phagocyte like a macrophage engulfs and digest pathogen
activated b lymphocytes differentiate into b memory and plasma cells which secrete antibodies
phagocytes activate t lymphocytes with complementary receptors to foreign antigen
b lymphocyte structure
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
secondary response
memory cells are already in blood and are able to rapid differentiate in to many plasma cells so eliminate infection before person feels ill
antigen structure
molecule made up of light and heavy chains, with a constant and variable region held by a hinge region
disulphide bridge
holds chains together on antibodies
variable region
forms complementary antigen binding site different amino acid sequence for each antibody
constant region
main body of antigen which attaches to cell membrane of phagocyte
hinge region
allows molecule to flex so can bind to antigens on different pathogens
how antibodies inactivate antigens
neutralisation, agglutination, precipitation which enhance phagocytosis
activation of complement system which leads to cell lysis
agglutination
large antibody binds multiple pathogens together so can’t infect cells and are engulfed by phagocyte
neutralisation
antibodies bind to antigen on surface of pathogen preventing it binding to target cell and clocks toxin activity
cell lysis by activation of complement
antibodies bind to antigens which activates proteins on surface to form pores on bacterial cell membrane
act as opsonins
antibodies bind to antigens, phagocyte as a receptor for content region of antibody, facilitates attachment of pathogen to phagocyte for engulfing by phagocytosis
Mantoux test
yes ro test for hypersensitivity to TB antigens, used before wether BCG vaccination needed, only used to test for people at high risk
4, 2, 1, 3
inflammation occurs at site within 72 hours producing red raised swelling (positive)
if person has had TB before immune response will be triggered
weak or no response indicates vaccination needed (negative)
tuberculin is injected underskin
5mm or more
induration which is considered positive in HIV infected persons, recent counted with TB, immunosuppressed persons
10mm or more
induration is considered positive if doing intravenous drugs, recent immigration from TB prevalent area, infants and children under 4
15mm or more
induration considered positive in anyone
point of care test
uses finger prick or mouth swab, immuoblot assay detects antibodies, 20-30 mins, low sensitivity
blood test
alternative test for HIV, detected presence of antibodies and p24 antigen using ELISA, higher sensitivity, detects 14-42 days after infection
false positive
when a test incorrectly indicates a substance Is present
false negative
when a test incorrectly indicates a substance is not there
p24 antigen
HIV antigen that is present in high concentration after the first few weeks of infection
enzyme linked immunosorbent assay test ELISA
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
active immunity
produced when body causes a immune response to a pathogen or vaccination, long term
passive immunity
person receives antibodies offering temporary protection, eventually antibodies broken down
natural passive immunity
maternal antibodies from placenta or breast milk, lasts as few months
artificial passive immunity
when a person receives antibodies via injection
allergic reaction
when immune system responds to an antigen that is non pathogenic, inflammatory
3, 4, 1, 5, 2, a
more allergens inhaled which attach to antibodies / lgE on mast cells
triggers inflammatory response. rhinitis symptoms, itchy and watery eyes
allergen causes antibody / lgE production
antibody attaches to mast cells sensitising person to allergen
mast cells triggered to release histamine as part of degranulation to remove antigen
allergic rhinitis
inflammation of inside of nose caused by allergen
hypersensitive reaction
any undesirable reaction produced by immune system, including allergic reaction and autoimmune response, only when host is already sensitise to allergen