Week 14 innate immune response Flashcards
Immunity -> two types
Immunity: two systems
-Innate immunity / nonspecific resistance / response of the immune system -> bodies immune response to a pathogen each time that pathogen is encountered
-Adaptive immunity / specific immunity -> immune system learns and the response to the pathogen improves each time the body is exposed to that pathogen
Innate immunity
->Response to pathogens same each time the body is exposed
Adaptive immunity
->Response to pathogens improves each time the pathogen is encountered.
->Characteristics: Specificity and memory
Specificity -> adaptive immunity: recognise a particular substance e.g., specific virus or bacteria
Memory
->Adaptive immune system: “remembers” previous encounters with a particular substance
->Future responses are faster, stronger, and longer-lasting
-> Adaptive response will get quicker, stronger and longer lasting than the first time it is exposed
Immune
If pathogen is destroyed before any symptoms develop, the person is said to be immune
Innate immunity
Rapid and non-specific response
Consists of;
-Physical Barriers -> can prevent access on a pathogen -> if pathogens cant enter the body they cannot cause disease
-Chemical Mediators
-Leukocytes (WBC)
-Inflammatory Response
Preps the body and enhances adaptive immune response
Key cells for innate immune reponse
Physical barriers
Skin:
-Epidermal Keratinized cells -> effective barrier, pathogens can’t enetr the body
-Sweat and secretions – lower pH -> makes pathogens environment hostile
Mouth / oral cavity:
* Salivary glands – lysozyme -> breaks down microbes
Stomach/GI tract:
-Low pH -> makes environment hostile to pathogens
Mucosal epithelia:
Found in;
-GI tract
-Respiratory tract
-Ears
-Nose
-Traps and removes
Traps pathogens and cilia remove pathogens
Tears, saliva, and urine wash these substances from body surfaces -> Pathogens cannot cause a disease if they cannot get into the body
Chemical mediators
Promote the immune response
Chemical Mediators
Promote the immune response
->Complement
> 20 Proteins in plasma
Normally inactive
Once activated - series of reactions - each complement protein activates the next
-Contribute to adaptive and innate systems -> Innate: “alternate pathway” of complement activation
-Bind to the cell membrane of the pathogen labelling it for phagocytosis (opsonization)
* Act as chemotactic agents to attract phagocytic cells to the site of inflammation
* Form damaging pores in the plasma membrane of the pathogen
* Cells swell and lyse (rupture)Chemical Mediators
Promote the immune response
*
Cytokines
Small signalling molecules, released from cells to initiate an immune response
Attract other immune cells into an area -> attracting factor
Interferons (IFNs)
Another type of cytokine
Viruses: Induce cells to produce viral nucleic acids and proteins
Causes damage to the cells, cells infected with viruses secrete interferons to signal adjacent cells to make antiviral proteins -> inhibiting viral reproduction in surrounding cells
Also activate other immune cells
Cells infected with viruses secrete interferons
->Travel to adjacent cells and induce them to make antiviral proteins
->Prevents production of new viral nucleic acids and proteins
->Inhibit viral reproduction in these surrounding cells
->Some IFNs also activate other immune cells (macrophages and NK cells)
Other chemical mediators
Other Chemical Mediators
-Histamine
-Prostaglandins
-Leukotrienes
Variously:
->vasodilation, increasing vascular permeability
->stimulating phagocytosis
->Promote inflammation
Overall part of the inflammatory cascade
Innate immunity -> white blood cells
Produced in red bone marrow / lymphatic tissue
Chemicals released from pathogens or damaged tissues attract WBC
->Leave blood and enter tissue
Phagocytic cells
Neutrophils normally first
->Release signals that increase inflammatory response
->Recruits and activates other immune cells - pus=dead neutrophils
Macrophages (monocytes that leave blood)
Larger - later stages of an infection ->cleaning up dead neutrophils and other cellular debris
Inflammatory cells
Inflammatory cells
->Basophils- are mobile cells
->Mast cells - non mobile cells in connective tissue, develop from basophils
->Eosinophils -> allergic response
-When activated: release (granules - contain lots of inflammatory factors) histamine and leukotrienes
-> Initiates inflammatory response
Natural killer cells
Natural Killer cells
-NK cells recognize classes of cells, e.g., tumour cells / virus-infected cells
-Kill their target cells
-Releasing chemicals that damage cell membranes -> causes the cells to lyse
Inflammatory response
Hallmark of the innate immune
-Tissue injury (e.g., bacterial infection causing damage)
-Mast cells/ basophils degranulate -> stimulates release chemical mediators in the cell and cause an effect on other cells
Stimulates releases or activation of chemical mediators
-Histamines, Prostaglandins, Leukotrienes, Complement
Vasodilation (particularly histamine / prostaglandin)
->Dilation of local capillaries
->Increased blood flow (brings WBC / phagocytes)
->Heat / redness
Increase in permeability of vascular system, causes a leakage of fluid from capillaries into the tissue -> causes swelling (oedema)-> allows complement to enter tissue -> attracts more phagocytes, clotting factors enter
