immune system

Question 1

features of the first line of defence

Answer 1

eyes: tears contain enzyme lysozyme (helps digest microbes)
respiratory tract: contains mucus (traps bacteria) which is then swallowed and digested
stomach: acidic pH (around 2)
skin: skin = tough barrier, pathogens only enter if cut, secrete sebum (inhibit bacterial growth)
skin flora: skin has own microbes which out-compete pathogens

Question 2

what is the non-specific immune response?`

Answer 2

happens in the same way for all microorganisms
to antigen specific
starts attacking microorganisms straight away

Question 3

inflammation

Answer 3

site of infection becomes red, warm, swollen, painful

Question 4

how does inflammation happen?

Answer 4

1. immune cell recognise foreign antigens, release molecules that trigger inflammation
2. molecules cause vasodilation around SofI, increasing blood flow
3. molecules also increase permeability of blood vessels
4. increased blood flow brings lots of immune cells, + increased permeability allows movement out of blood vessel into infected tissue

Question 5

what is an interferon?

Answer 5

anti viral protein

Question 6

how do interferons prevent viruses spreading?

Answer 6

• prevent viral replication by inhibiting production of viral proteins
activate cells involved in specific immune system
activate other mechanisms of non specific immune response
eg. promote inflammation

Question 7

what is a phagocyte?

Answer 7

WBC that carries out phagocytosis (engulfment)
found in blood / tissues
first cells to respond to pathogen

Question 8

how does phagocytosis work?

Answer 8

1. phagocyte recognises antigens on pathogen
2. cytoplasm engulf pathogen via formation of pseudopodia
3. ingestion of bacteria via endocytosis
4. foreign material enclosed in a vesicle
   → pathogen enclosed in phagocytic vacuole

Question 9

how does lysozyme action work?

Answer 9

lysosome fuses with phagocytic vesicle, enzymes break down pathogen

Question 10

antigen presenting cell

Answer 10

after phagocytosis + lysosome action

presents pathogens antigens on surface to activate other immune cells

Question 11

antigen

Answer 11

anything that causes an immune response

usually foreign proteins / glycoproteins

Question 12

antibody

agglutination

Answer 12

microorganisms are clumped together for easier phagocytosis