Innate immune system Flashcards
What are leukocytes
They are all the cells involved in the immune system which is from the stem cells in bone marrow
So summarise the function fo the innate immune system
- To prevent entry of the pathogen
- To prevent pathogens from causing harm
- to attract other immune cells
- to activate our 3rd line of defense
The innate immune system does not use MHC markers, why?
This is as the response is not specific and do not read the markers to be faster
What are the main pahgocytes in innate
neutrophils, macrophages , dentritic cells
What are phagocyte
leukocytes that engulf and destroy foreign matter though endocytosis
What are the two steps in phagoycytosis
Phagocyte engulfs the pathogen
Lysomes attact to pathogen and release digestive enzymes
How do phagocytes communicate with others?
Relase of cytokines
What are cytokines
Signalling molecules that stimulate,recruit and multiply other immune cells which can help guide them to the site of infection or injury
What are nuetrophils
Phagocytes that contain granules and circulate in the bloodstream.
whcih engulf microbes and kills them with toxci chemicals
Who arrives at the infection site first?
Neutrophils
How many pathogens can neutrophils engulf
1-2 times before it dies
Why is there pus explain breifly tf is happening there
Neutrophils common compoenent is pus, and because theres numerous neutrophils in the blood stream and can only digest 1-2 pathogens, theres a build up of dead neutrophils.
What are macrophages
They are a type of pahgocyte that is found at the site of infection that live long
What are the two key roles of macrophages
And for the second role what does that do
- To undergo phagocytosis
- To use MHC 2 class markers to display antigens from the consumed pathogens onto their surface. This allows the 3rd line of defense to be activated
What are dentritic cells
Found near or on body surfaces and is a type of phagocyte
What are the two roles of dentritic cells
Say the same roles as macrophages
What are the steps of Antigen presentation
1.Phagocytosis of pahtogen
2.Fusion with lysosome
3.ENzymes start to degrade pathogen
4.Pathogen breaks into small fragments
5.Fragments of antigen presented on the cell surface
What are the purpose of the dentrites
It increases the surface area to
volume ratio to kill and prevent pathjogens
What are natural killer cells
They target own unheathy cells or infected cells by he usage of two receptors- Killer inhibutory receptor and killer activation receptor
What cells do NK cells target
virally infected, damaged or cancerous cells
What happens in NK killer cells
In an healthy cell, the killer inhibitory receptor check for MHC 1 markers and the killer activation receptors bind to certain molecules that appear on cells undergoing cellular stress. SO no attack
But if not enough MHC 1 markers are foun due viralinfections or caners, the killer inhibitory receptors cant bind and cell death is then initated.
How does NK cells kill cells when cell death is activated
Releases perforins and granzymes which will trigger the cell’s death by apoptosis
What is a mast cell and why is it different to other immune cells
and when do they do it
They are responsible for the release of histamine byy degranulating when they detect injury to surrounsing cells, stimulated by antigens, allergens
Where is mast cells found
Thy are found between connective tissues especially close to the external enviroemnt where pahtogens are likely to enter
What do histamines do?
They cause vasodilation of blood vessels and are involved in inflammation
Why is vasodilation good during immune response
It increases blood flow and increases permeriability of vessels to allow more leukocytes to enter into the tissues
What do Eosinophils do
They release toxic chemical mediators found in tissues that target large pathogens, by degranulating.
The cell mediators are foound in their granules btw
Degranulation is what kinda process
Exocytosis
Whats the most common typa targert for eosinophils?
Parasites big pathogens
What are non cellular components of second line of defense
Complement protiens and interferons
What is complement protiens
It is a set of protiens that float around the body in the blood and act as an innate defense against pathogens
What are the steps for complement protiens in resposne to a pathogen
1. Complement activation( basically the activation of a complement protien)
2. Complement cascade- other protiens are also all activated
3. Complement outcomes- Opsonisation , chemotaxis, lysis
What is opsonisation
Its when complement protiens stick on the surface of pahtogens to make it easier for the cells of the immune system to recognise as foreign and undergo phagocytossis
What is chemotaxis
Complement protiens gather around the pathogen and attract phagocytes to the pathogen,
increasing chance of it being destroyed
What is lysis
Complement protiens will form a Membrane attack complex, which creates pores on the membrane of pathogens, causing it to swell and burst via lysis, which is the sudden influx of fluid into the pathogen.
What are interferons
and therefore how does it help
They are cytokines that are released by virally infected cells to warn neibouring cells about viral infection and to heightnen their defenses by interacting with their receptors, which therefore localises the infection site.
What are the ways interferons interact with cells receptors
- Signals uninfected cells to redcue protien synthesis and destroy RNA in the cells
- Induces apoptosis to infected neighbouring cells to undergo apoptosis
- Activates immune cells
What is the INFlammatory response
It is response to pathogenic infection and injury, by ellminating the effects of injury by clearning out any damaged or destroyed cells and preventing further infection to an affected tissue.
What is the purposes of the inflammatory response
- Its purpose is to elimate the effects of an injury
- Clear out any damaged ro destroyed cells
- Initiates repair
- Prevents potential pathogens from entering
What is the initation step
during injury, the surface cells are damaged, allowing the entry if pathogens into the body.
In response the immune cells in nearby tissues/cells release cytokines
Mast cells also degranulate and release histamine
What are the 3 main stages of inflammation
Initation , vasodilation, migration
What is Vasodilation step
And explain what does vasodilation do
When histamines released by mast cells travel to nearby blood vessels and bind to specific receptors, which triggers vasodilation.
Vasodilation is the widening of blood vessels and increases permiability of the blood vessels.
What is the migration step?
Th vasodilation and ioncreased permiability of blood vessels allows much of the innate immune system cells to leak through towards the site of injury
this includes phagocytes attracted by cytokines and complement protiens
What symptoms do you expect of inflammation
- Swelling- leaky blood vessels therefore more fluod in my tissues NOT VASODILATION
- Redness- increased BF
3.Heat- Increased activity of immune cells at the area - Pain - inflammatory chemicals
