Anaphylactic shock and Type 1 hypersensitivity Flashcards
What is shock?
Failure to maintain an adequate cardiac output, or similar definition.
What are the different types of shock? Give examples of each.
Hypovolaemic - haemorrhage, severe fluid loss
Obstructive - pulmonary embolus or tamponade
Cardiogenic - MI, valvular disease, myocarditis, cardiomyopathy
Distributive - septic, anaphylactic
What is sepsis?
Organ injury/damage in response to infection
How many cells can those in the innate and adaptive immune systems recognise?
Innate - each can recognise a variety, 20-30
Adaptive- each recognises only one
How diverse are cells in the innate and adaptive system?
Innate - all cells are the same
Adaptive - vast diversity of cells
How are antigen receptors encoded?
Innate - directly
Adaptive - each cell randomly mutates gene
In which system is there immuno-memory?
Adaptive - B and T memory cells
In which immune system is there danger of autoimmunity?
Adaptive - clonal deletion is required to remove autoreactive clones
What cells are in the innate and adaptive immune system?
Innate - neutrophils, monocytes, eosinophils, mast cells
Adaptive - B and T lymphocytes
Where are T and B cells made?
T - thymus gland
B - bone marrow
What is central tolerance?
When lymphocytes encounter an antigen from a cell and fit into receptor for a response, then lymphocyte deleted
What are Fc receptors?
Fragment of crystallisation, cells of the innate system bind to antibodies via these, meaning they can use their antigen specificty
What are the cells of the innate immune system?
Neutrophils, monocytes, eosinophils, mast cells, basophils
What are the roles of IgA?
Found in mucous, saliva, tears and breast milk, blocks pathogen binding via neutralisation
What are the roles of IgE?
Protects against parasitic worms, responsible for allergic reactions, activates mast cells
What is the role of IgM?
block pathogen binding, activate complement, may be attached to B cell surface or secreted into blood
What is the role of IgG?
Secreted by plasma cells, blocks pathogen binding, activates complement and opsonises antigens for phagocytes
What is the role of IgD?
Not secreted, unknown role
How can mast cells and basophils be activated?
- Cross linking of surface IgE by antigen
- via complement proteins C3a and C5a
- via nerves: axon reflex of sensory nerves, substance P (released from primary afferent neurons)
- direct contact with pathogen through innate receptors (TLRs)
What is atopy?
hypersensitivity to environmental antigens leading to a IgE response
What are the local manifestations of type 1 hypersensitivity?
allergic rhinitis, asthma, atopic eczema, urticaria, angiodema
What are the systemic manifestations of type 1 hypersensitivity?
Anaphylactic shock
Why do you get a drop in blood pressure in anaphylactic shock?
Leak of fluid into interstitial space (resdistribution) & veins dilate
What is urticaria?
Hives, raised itchy red rash, dermis inflammation, sore red itchy eyes
