Immunity Flashcards
How do epithelial cells block the entry of microorganisms?
selectively permeable barrier, natural antibiotics, produce cytokines and chemokines to attract immune cells, produce mucins and transport antibodies
Where do chemokines and cytokines diffuse into from the epithelial cells?
lamina propria and blood
Why does opsonisation occur?
So bacteria are easier to phagocytose
What 2 things are extravasated at the site of infection?
antibodies and complement
What are the 5 signs of inflammation?
heat, swelling, redness, pain, loss of function
What are the features of innate immunity?
inbuilt/natural/native, present from birth, not specific, not enhanced by second exposure, no memory, cellular and humoral components
What are the features of adaptive immunity?
acquired, learnt by experience, pathogen-specific, enhanced by second exposure, has memory, cellular and humoral components
What do antibodies tell us?
Which infections an individual has been exposed to
The adaptive system is only present in which group of animals?
Vertebrates
How many classes of antibodies are there and what are they?
5 classes
IgG, IgA, IgM, IgE, IgD
What is the role of macrophages?
phagocytosis and presentation of antigens to T lymphocytes
What are macrophages called before they enter the tissue?
Monocytes
Which blood cell type is anti-parasitic?
Eosinophils
Which cells are involved in the innate response?
macrophages, neutrophils, eosinophils, basophils, mast cells and natural killer cells
Which cells have a 5 lobed nucleus?
Neutrophils
What is the most plentiful WBC?
Neutrophils
What is the smallest WBC?
Lymphocyte
In which cell may the nucleus be obscured and why?
Basophils
They have so many granules within them.
Do neutrophils have receptors?
Yes
for many bacterial constituents
What kind of conditions are neutrophils specialised for and why?
Anaerobic conditions
Because they are required in damaged tissue which is often anaerobic due to lack of blood supply.
What is the first response to inflammation?
Neutrophil arrival
What makes up pus and why?
Dead neutrophils
They are unable to synthesise more granules once activated. Therefore once they have used up all their granules, they die.
What happens when pathogens are too big to digest?
Phagocytes release their lysosomal contents onto the pathogens’ surface.
What do macrophages phagocytose?
microbial cells and damaged or unwanted cells
Why do macrophages have a long lifespan?
They can generate lysosomes as needed.
Define opsonisation
The coating of a microorganism by antibodies and complement to render it recognisable as foreign by phagocytes.
Do natural killer cells have antigen receptors?
No
Which cells can cause apoptosis in viral cells and how?
Natural killer cells
By pumping proteases through pores into the viral cells
What happens to people lacking in NK cells?
They have persistent viral infections
What can activated NK cells that most cells can produce?
IFN-alpha
IFN-beta
What is the effect of cytokines on NK cells?
induce proliferation and activation of NK cells
What are the effects of interferon?
inhibits viral replication and activates other cells which kill pathogens
Where would you find lysozyme and what does it do?
in serum and tears and it breaks down bacterial peptidoglycan cell walls
What does the complement system do?
Marks pathogens for destruction by covalently binding to their surface using the proteins in the blood and lymph. (C1-C9)
Which complement proteins make up the membrane attack complex?
C5-C9
What is the role of T helper cells?
activate B lymphocytes and macrophages
What is the B cell receptor?
A surface immunoglobulin
What is the T cell receptor?
A non-membrane bound, antigen receptor.
What are the roles of antibodies?
neutralise bacteria, opsonise to promote phagocytosis and activate complement
What is clonal selection?
Raising the clonal frequency of cells with a particular antigen specificity.
What does the adaptive immune system do to ensure that the number of lymphocytes with that specificity never falls as low?
Seeding to memory using memory cells
Give some examples of clearance of pathogens from epithelial surfaces
rapid cell regeneration, tears, urine, vomiting, muociliary escalator and coughing
