Week 14 innate immune response

Question 1

Immunity -> two types

Answer 1

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

Question 2

Innate immunity

Answer 2

->Response to pathogens same each time the body is exposed

Question 3

Adaptive immunity

Answer 3

->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

Question 4

Memory

Answer 4

->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

Question 5

Immune

Answer 5

If pathogen is destroyed before any symptoms develop, the person is said to be immune

Question 6

Innate immunity

Answer 6

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

Question 7

Key cells for innate immune reponse

Question 8

Physical barriers

Answer 8

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

Question 9

Chemical mediators

Answer 9

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
*

Question 10

Cytokines

Answer 10

Small signalling molecules, released from cells to initiate an immune response
Attract other immune cells into an area -> attracting factor

Question 11

Interferons (IFNs)

Answer 11

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)

Question 12

Other chemical mediators

Answer 12

Other Chemical Mediators
-Histamine
-Prostaglandins
-Leukotrienes
Variously:
->vasodilation, increasing vascular permeability
->stimulating phagocytosis
->Promote inflammation
Overall part of the inflammatory cascade

Question 13

Innate immunity -> white blood cells

Answer 13

Produced in red bone marrow / lymphatic tissue
Chemicals released from pathogens or damaged tissues attract WBC
->Leave blood and enter tissue

Question 14

Phagocytic cells

Answer 14

Neutrophils normally first
->Release signals that increase inflammatory response
->Recruits and activates other immune cells - pus=dead neutrophils

Question 15

Macrophages (monocytes that leave blood)

Answer 15

Larger - later stages of an infection ->cleaning up dead neutrophils and other cellular debris

Question 16

Inflammatory cells

Answer 16

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

Question 17

Natural killer cells

Answer 17

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

Question 18

Inflammatory response

Answer 18

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