non specific defence

Question 1

what are primary defences

Answer 1

physical and chemical defences that prevent entry pathogen into body

non specific as work the same for all pathogens

Question 2

what are the primary defences

Answer 2

skin

mucous membranes

explusive reflexes

tears

wax in ear canal

non pathogenic bacteria

Question 3

mucous membrane role in primary defence

Answer 3

• line parts body contact pathogen eg airway/ digestive tract
• mucus secreted from goblet cells, has antimicrobial enzymes
  -cilia waft mucus away airway

Question 3

expulsive reflex role in primary defence

Answer 3

-cough/ sneeze
- automatic
- expel foreign bodies

Question 3

skins role in primary defence

Answer 3

• outer layer dead cells with keratin
• low moisture, pH and high salinity prevent microorgs replicating on skin

Question 3

non specific secondary defences

Answer 3

blood clot

inflammation

phagocytes

Question 4

tears role in primary defence

Answer 4

have lysosomes which are antibacterial

Question 4

what is secondary defences

Answer 4

responds to pathogens that have passed primary defence

still non specific as dont distinguish between different pathogens

Question 4

non pathogenic bacteria role in primary defence

Answer 4

in digestive tract to compete with pathogens

Question 4

wound repair role in secondary defence

Answer 4

• blood clot
• form scab to allow new layer skin form

Question 4

how does blood clot

Answer 4

collagen exposed - release clotting factors

inactive thrombokinase to active thrombokinase

active TBK with calcium to active prothrombin to thrombin

thrombin catalyses conversion soluble fibrinogen to insoluble fibrin

fibrin forms mesh trapping RBC

clot forms

new cells grow
tissue contracts to draw edges wound together
new blood vessels form

Question 4

inflammations role in second line of defence

Answer 4

mast cells secrete histamine causing:

vasodilation so blood flow inc
- hotter to prevent reproduce pathogens

capillaries more leaky flushing pathogens to tissue fluid
- swelling (odema)

pathogens leave blood and enter tissue fluid

histamines stimulates cells to secrete cytokines to encourage phagocytes to area

Question 4

role of neutrophils

Answer 4

circulate in blood
rush to infection site and engulf pathogens
die and accumulate as pus

come from bone marrow
lobed nucleus

Question 4

role of fever

Answer 4

higher temp inhibits pathogen reproduction
specific immune system works faster

Question 4

phagocytes role in second line defence + 3 types

Answer 4

engulf pathogens and foreign material

neutrophils/macrophage/dendritic

Question 4

role dendritic cells

Answer 4

long processes for large SA
take foreign material to lymph nodes
Antigen presenting
near surfaces

Question 4

what is the third line of defence

Answer 4

fever
phagocytosis

Question 5

role phagocytosis

Answer 5

phagocytes engulf and destroy pathogens

collect at site infection

Question 5

role of macrophage/monocyte

Answer 5

enter tissue fluid where form macrophages
long lived
present antigens to lymphocytes

Question 5

stages of phagocytosis

Answer 5

• phagocyte recognises non self
• engulfs pathogen form phagosome (invagination of plasma membrane by cytoskeleton)
• lysosomes combine with phagosome to form phagolysosome
• digestive enzymes in lysosome breaks down pathogen
• digested material absorbed and waste released
• can display antigens

Question 5

what are cytokines

Answer 5

cell signalling molecules
stimulate other phagocytes to area
inc body temp + stim specific response

Question 5

what are opsonins

Answer 5

chemicals that bind to pathogens and ‘tag’ them for easy recognition by phagocytes

phagocyte has receptors complementary to opsonin allowing easier phagocytosis

Question 6

how does APC work

Answer 6

antigen combines special protein complex and placed on apc plasma membrane