disease resulting from an abnormal immune response in which the immune system treats 'self' antigens as foreign antigens and launches an immune response against them
targets healthy tissue
autoimmune disease - lupus
immune system attacking cells in connective tissue
damages tissue and causes painful inflammation
skin, joint, heart, lungs
autoimmune disease - rheutmatoid arthritis
caused by immune system attacking cell joints
damages tissue and causes painful inflammation
result in painful deformity and immobility
epidemic
rapid spread of disease through a high proportion of the population. A worldwide epidemic is called a pandemic
active immunity
immune system is activated and manufactures its own antibodies
passive immunity
antibodies are supplied from another source
natural immunity
immunity produced through normal life processes
artificial immunity
immunity produced after medical intervention
opsonin
type of antibody that attach to antigens on surface of a pathogen
cytokines
chemical messengers that bind to cell surface receptors and are involved in the immune response
monokines: released by macrophages and stimulate B cells to differentiate
interleukins: stimulate B cell clonal expansion
interferon: stimulated T killer cells
skin cells made of kerotinocytes
explusive reflexes
when sensitive areas targetted - triggers coughing, sneezing and vomitting. - sudden explusion of air or fluid can carry microorganisms out with it
inflammation
swelling and redness of tissue caused by infection
mast cells
specialised cells that detect pathogens and then release histamine to initiate inflammation
secondary defences
activated after the pathogen has gained entry into the body. There are both specific and non-specific secondary defences
clonal selection
process by which T cells and B cells become activated when their cell surface receptors/ antibodies bind to a matching pathogen
clonal expansion
happens after clonal selection. activated T and B cells increase in number through cell division (mitosis) and begin to differentiate into specialised cells
mast cells in tissue detect pathogen and release cell signalling chemical called histamine
histamine causes vasodilation which widens blood vessels and makes wall of capillaries in tissue more permeable
WBC (phagocytes) circulating in bloodstream can leave bloodstream through wall of capillaries and reach the site of infection in tissue
WBC attack pathogens at the site of infection in the tissue.
5. plasma also leaves bloodstream which results in an increase in tissue fluid - causes swelling (oedema)
6. excess tissue fluid is drained into lymphatic system
7. other immune cells (lymphocytes) are stored in lymphatic system come into contact with pathogens in drained tissue fluid and activate a specific immune response
indirect transmission: vectors
direct transmission: direct contact, sexual, blood, droplet infection, faeco-oral transmission, spores
protists
eukaryotic organisms
mostly unicellular
can cause disease by entering host cells and feeding on contents as they grow
viruses
not living
small particles which contain genetic material
invade and take over cells so they produce more copies of the virus
cell then dies and releases new virus particles which then infect healthy cells
herd immunity
when a significant proportion of population has been vaccinated, protects individuals who have not developed immunity
ring vaccination
when a disease case is reported, everyone in vicinity is vaccinated to prevent spread
vaccination
deliberate exposure to antigenic material that has been rendered harmless - activates specific immune system and causes immunity
types of vaccines
live vaccines (similar pathogen)
toxoid vaccine (targets toxin)
attenuated (weakened version of pathogen)
antigen (loose antigen)
inactivated (dead pathogens)
T killer cells
attack and kill host body cells that are infected with pathogen. They recognise foreign antigens
T helper cells
release cell signalling molecules called cytokines that stimulate cells to develop and stimulate phagocytosis by phagocytes
B memory
immunilogical memory (antibodies) and remain in the body for a number of years
T regulator cells
specialised t cells which shut down immune system response after pathogens have been removed
plasma cells (B cells)
specialised B cells which circulate in blood, manufacturing and secreting antibodies which are specific to antigen
T memory cells
remain in bloodstream in low levels in case reinfection occurs and provides long term immunity. immunilogical memory
physical defences
prevent spread of pathogens
chemical defences
damage pathogens directly
passive defences
defences that are present before the infection
active defence
changes to defences in response to a pathogen infection
callose
large polysaccharide
deposited at end of sieve plates
blocks spread of pathogens through phloem
blocks plasmodesmata
tylose
balloon like swelling or projection that fills the xylem vessel and eventually blocks it
contain high concentration of anti-microbial chemicals
T cell activation
clonal selection: wait for antigen that is complementary to a t cell - antigens from pathogen or antigen presenting cells (macrophages)
clonal expansion: t memory, helper, killer, regulator