Non-Specific Immune Response Flashcards
How can pathogens enter the body? - 4
- Cuts in skin
- Digestive system in contaminated food and drink
- Respiratory system - inhalation
- Other mucosal surfaces - inside of mouth/nose/genitals
List 6 natural barriers to pathogens
- Stomach Acid
- Skin
- Skin Flora
- Gut Flora
- Lysozymes
- Epithelial cells
How does stomach acid work as a barrier?
The low pH destroys bacteria
What type of acid is stomach acid?
HCl
What pH is stomach acid?
Less than 2
How could pathogens still cause disease in spite of stomach acid?
Could survive and pass into intestines and invade the cells of the gut wall
How does skin work as a barrier?
- It itself is a physical barrier
- Any cuts/damage sealed by blood clotting
How does skin flora work as a barrier? 3
- Harmless bacteria prevent colonisation of pathogens as they are well adapted to the skin environment
- Compete with pathogens for nutrients and space
- Limit pathogen numbers
How does gut flora work as a barrier?
Same as skin flora - harmless bacteria competitively excluding pathogens
How and where are lysosomes produced?
Musocal surfaces produce secretins containing lysozymes
Give 3 examples of secretins containing lysozymes.
- Tears
- Saliva
- Mucus
How do lysozymes work as a natural barrier?
Lysozymes damage bacterial cell walls - causing them to burst open in lysis
How do epithelial cells work as a natural barrier?
They transport bacteria trapped in mucus to the throat where it is swallowed into stomach acid
Define non specific immune response
Fast immune response to all pathogens regardless of antigen
What is the advantage of the non-specific immune response?
Immediate and quick
What is inflammation?
The site where the pathogen enters - infection site - is red swollen and painful
How does inflammation occur?
- Damaged white blood cells and mast cells detect foreign antigens
- Releases histamines
- These trigger inflammation
Where are histamines released and produced?
Locally to the infection site
What 2 things does inflammation cause?
- Increased permeability of blood vessels
- Vasodilation
How does vasodilation help the immune response?
Increased blood flow in capillaries to infected site - more WBCs to fight infection
How does increased permeability of blood vessels help the immune response?
WBCs and antibodies leak out into tissue to fight pathogens
What type of substance is an interferon?
A protein
Where are interferons produced?
From cells infected with viruses
How do interferons help combat viruses?
- Diffuses to surrounding cells
- Inhibiting viral replication
- Inhibiting production of viral proteins
Other than combating viruses, how else do interferons help in immune response?
- Activates WBCs e.g T Cells involved in specific immune response
- Promotes other mechanisms of non specific immune response e.g inflammation
Define phagocyte
A white blood cell engulfing pathogens and destroying them using lysozymes
What is a lysosome?
Organelle containing digestive enzymes e.g lysozymes
Describe the mechanism of phagocytosis.
- Phagocyte recognises antigens on the pathogen
- The cytoplasm of the phagocyte engulfs the pathogen
- Pathogen contained in phagocytic vacuole
- Lysosome fuses with vacuole
- Enzymes break down pathogen
- Phagocytes present pathogen’s antigens on its surface
- Becomes an antigen presenting cell - APC
- Activates other immune system cells
