unit 4 aos 1 Flashcards
self vs non self cells
self: cells & molecules that make up your own body, contain MHC 1 markers to identify cells as self
non-self: refers to everything else, eg. antigens
antigen
unique molecule found on the surface of pathogens that initiates an immune response
they are used to recognise if a cell/molecule is self or non-self, if non-self, an immune response is initiated
> allergen: antigens that trigger allergic response.
self antigens (markers)
found on the surface of cells and mark them as ‘self’ so that the immune system doesn’t attack them
non self antigens
recognised by the leukocyte (wbc), immune system tries to eliminate if detected in the body
pathogen
microorganism capable of causing disease or harm. secrete toxins, wich create an immune response
what happens when a pathogen enters- innate immunity
- blood is directed to the site (inflammation)
- fever
types of cellular pathogens
have a cellular structure & are living organisms
- bacteria: unicellular, cause disease through neurotoxins & endotoxins
- fungi: eukaryotic, yeast & moulds
- parasites: live off a host organism while causing the host harm
- protists: eukaryotic, inhibit nucleic acid synthesis & stages of cellular respiration
types of non-cellular pathogens
non-living, do not have a cellular structure
- viruses: insert genetic material into a host cell and use the cell to replicate, eg. influenza
- prions: abnormally folded proteins that can infect other proteins, causing them to misfold
physical barriers to infection in animals
barriers that block or hinder pathogens from entering an organism
- intact skin
- mucous membranes/secretions
- hair/oils/wax
- expulsion reflexes
physical barriers to infection in plants
prevent pathogens from entering the organism
- thick bark
- waxy cuticle
- close stomata
chemical barriers to infection in animals
barriers that produce chemical substances that make an environment unliveable for a pathogen.
- lysosome enzymes in tears and saliva
- hydrochloric (stomach) acid destroys pathogens that have been eaten/ swallowed
- acidic sweat that destroys pathogens growing on the surface of the body
- antibacterial compounds in earwax
chemical barriers to infection in plants
involve the production of chemicals/ enzymes which are harmful to the pathogen & affect its functioning
- chitnases (antifungal properties)
- phenols (secreted by wounded plants, repelling invading microorganisms)
- trichomes
microbiota barriers to infection
presence of non-pathogenic bacteria in the body/plant that prevents the growth of pathogenic bacteria as they compete for space & nutrients
- on the skin, lower gastrointestinal tract and the vagina
the second line of defence (innate immune response)
innate immune response which destroys any pathogens which have entered the body
- non-specific, rapid, no immunological memory
- responds in the same way regardless of the type of pathogen or antigen present.
what triggers the inflammatory response
mast cells release histamine to initiate inflammatory response.
release of histamine causes:
- vasodilation (dilation of blood vessels)
- increased permeability of blood vessels
- chemoattractant to phagocytes (attract phagocytes to the area)
steps of the inflammatory response
- initiation- pathogen gets in the body,breaching first LOD, damaged cells release cytokines, attracting neutrophils, which trigger mast cells to release histamine
- vasodilation- mast cells degranulate releasing histamine- causes vasodilation, increased permeability of blood, meaning inc. bloodflow and more phagocytes can enter. swelling, redness and warmth in the area
- migration- more immune cells travel to infection site, wound is blocked by platelets & clotting factors
- repair- cytokines signal neutrophils to phagocytose the pathogens, new cells form underneath wound
> continues until infection/pathogen is cleared
symptoms of the inflammatory response
- increased blood flow (vasodilation)
- increased permeability of blood
- redness
- swelling
- heat
- pain
mast cells
cause the inflammatory response
- leukocytes embedded in connective tissue, they become activated when they detect injury to surrounding cells, degranulate to release histamine, which causes:
- vasodilation of blood vessels (more blood flow)
- increased permeability of blood vessels (leukocytes can get out)
- chemoattractant to phagocytes
MHC 1 & MHC 2
major histocompatibility complex- bind to antigens and present them to T cells
- MHC 1 markers: self markers found on all nucleated cells
- MHC 2 markers: self markers only found on APCs (macrophages, dendritic cells, B lymphocytes), activate helper T cells of the adaptive immune response
phagocyte & types
- consume and destroy foreign or dead material
- engulf & break down pathogens
- engage in phagocytosis
- Release cytokines that attract additional immune cells to the site of infection
> neutrophils: granulocyte, disrupts pathogen cell membrane, die after phagocytosis (pus)
> macrophages: big eater, phagocytose a large number of pathogens that have been agglutinated. APC presenting antigens on MHCII markers, flagging the 3 LOD
> dendritic cells: APC, better than macrophages, presenting antigens on MHCII markers, flagging the 3 LOD, has grooves/shoots on the outside increase SA
natural killer cells (NK)
- granulocytes, type of lymphocyte
- destroy cells presenting a non-self antigen on their MHC 1 markers by causing them to undergo involuntary apoptosis
cytokines
- signalling molecules
- released in response to cell damage or presence of a pathogen
- promote antibody response & activate macrophages