Communicable diseases Flashcards
Explain why vaccinations are an example of active immunity (2)
- antibodies are produced by person who is injected
- activation of lymphocytes + memory cells remain
explain why it is not possible to protect against the different pathogens using only 1 vaccine ?
- diff pathogens have diff antigens
- antigens have a specific shape
- antibody shape must be complimentary to antigen shape
Outline the process of phagocytosis
- phagocyte engulfs pathogen + forms phagosome
- a lysosome fuses with phagocyte forming a phagolysosome (digestive enzymes break down pathogen)
- phagocyte presents the pathogen’s antigens on its surface = become APC ( macrophages only)
what are the primary non- specific responses (5) ?
- skin
- mucous membranes
- blood clotting
- wound repair
- expulsive reflexes
what is inflammation caused by + how does this help against pathogens
- caused by tissue damage
- activated mast cells release histamine
- causes vasodilation = more blood flow to skin surface so hot + red
- makes blood vessel wall more permeable so can leak tissue fluid , this causes swelling
what are the 2 secondary non-specific responses ?
- inflammation
- phagocytosis
Outline the events in the specific immune response
- T helper cell receptors which are complementary in shape to antigen on APC bind
- T helper cell is activated = clonal selection
T lymphocyte undergoes clonal expansion = divides by mitosis to produce t helper (produce interleukins ) , killer ( release perforin) + t regulatory cells - b lymphocyte antibody and complementary antigen bind + interleukins produced by t-helper cells activate B - cells (clonal selection)
- B lymphocytes divide by mitosis to produce plasma (copies) + memory cells
Suggest why antibodies specific to nuclear proteins are not normally made (1)
nuclear proteins normally, hidden in nucleus = not on surface
Outline the processes that lead to the production of antibodies against an unfamiliar bacterium ( 3 )
= B lymphocytes have antigen receptor complementary to, only one antigen (1)
= activated, B cell divides by mitosis (1)
= forms plasma cells
= which secrete antibodies specific / complementary, to antigen (1)
Explain how helper T cells act to speed up the processes that lead to the production of antibodies against an unfamiliar bacterium (2)
= release interleukins
= = stimulates B cell to divide by mitosis
Outline the action of opsonins
= increase likelihood of phagocytosis (1)
= binds to pathogen AND phagocyte
Describe how the structure of antibodies allows them to perform their function (7)
- Y shaped glycoprotein
- made of 2 light (shorter ) and 2 heavy chains
- variable region = allows antigen to bind
- 2 variable regions allow more than 1 antigen to bind
- hinge region allows flexibility
- disulphide bond holds polypeptide chains together
Outline the mode of action of antibodies in defending the body against pathogens by describing the processes of neutralisation and agglutination (4)
neutralisation = bind to toxins + prevent entry to host cell
agglutination = clump together many pathogens + increasing likelihood of phagocytosis
When is primary immune response
After vaccination = involves clonal selection + expansion
What is secondary immune response + why is it faster
Secondary immune response after infection + faster because clonal selection + expansion already happened therefore memory cells present
