immune system Flashcards
whats the 2 main types of white blood cell
Phagocytes and Lymphocytes
movement of phagocytes
easily pass through blood vessel walls into surrounding tissue and move towards pathogens or toxins
what can phagocytes do after moving into a tissue / cell (2)
ingest and absorb the pathogens or toxins
release an enzyme to destroy them
what does phagocytes do after absorbing a pathogen
send out chemical messages that help nearby lymphocytes to identify the type of antibody needed to neutralise them
what do Pathogens have on their surface
have chemicals that are called antigens.
what does each lymphocyte carry?
specific type of antibody
what happens when lymphocyte with the appropriate antibody meets the antigen
lymphocyte reproduces quickly, and makes many copies of the antibody that neutralises the pathogen.
3 diff ways antibodys neutralise pathogens
- bind pathogens and damage or destroy them
- coat pathogens, clumping them together so that they are easily ingested by phagocytes
- bind to pathogen and release chemical signals to attract more phagocytes
how many natural barriers against pathogens do we have
6
what are the bodys natural barriers against pathogens
- skin
- blood clotting
- Inflammation to localise breaks in the barrier
- Phagocytosis to destroy invading microbes
- Ciliated mucous membranes that trap microbes in inhaled air
- Lysozyme in tears, saliva and stomach acid that kills bacteria.
why is the skin good as a natural barrier
complex organ has physical, chemical, and microbiological barriers to protect the host from external insults.
why is Blood clotting to seal wounds a good natural barrier
platelet plug is formed, and the external bleeding stops.
small molecules, called clotting factors, cause strands of blood-borne materials, called fibrin, to stick together and seal the inside of the wound
why is inflammation to localise breaks in the barrier good natural barrier
In response to injury and infection, specialised immune cells called mast cells release histamine.
Histamine causes blood vessels to widen (vasodilation).
This increases blood flow to the area.
increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.
where does histamine come from
mast cells
what do mast cells release
histamine
what do histamine cause
Histamine causes blood vessels to widen (vasodilation).
what does the vasodilation because of histamine do
increases blood flow to the area
why is phagocytosis a good natural barrier
cells can engulf pathogens or cells and internalise them
why are ciliated mucous membranes a good natural barrier
propel a liquid layer of mucus that covers the airways.
traps pathogens and other particles, preventing them from reaching the lungs.
what is found in tears, saliva and stomach acid
lysozomes
what do lyzozomes do
kill bacteria
what are lyzozomes
form of chemical defence against infection.
why does a specific immune response develope
as a result of antigens being recognised as foreign to the body
whats the 2 different immune responses
Humoral
Cell-Mediated