20. Anaphylactic shock Flashcards
What is meant by shock?
Failure to maintain an adequate cardiac ouput
What are the different types of shock?
Hypovolaemic - haemorrhage or severe fluid loss
Obstructive - pulmonary emoboli
Cardiogenic - MI, valvular disease, cardiomyopathy
Distributive - septic or anaphylactic - due to leak from capillaries to the tissues
Briefly describe innate immunity
Neutrophils, monocytes, macrophages, eosinophils and mast cells
Antigen receptors on surface (toll-like receptors and lectins) - all the cells are identical and the antigens are what differ
These cells are encoded for genetically
These are not clonal and do not mediate memory
No danger of autoimmunity because everyone has these
Briefly describe adaptive immunity
B and T lymphocytes
Each of these individual cells have just one specificity e.g. single type of antibody one B lymphocyte
These cells are not encoded for genetically - arise randomly from mutations
Danger of autoimmunity due to the random nature of the mutation process
What are the main features of the adaptive immune system?
Self-tolerance
Memory
What is meant by clonal deletion?
Autoreactive - if B or T lymphocytes have expressed receptors for self antigens, then they will be deleted before the lymphocytes are released into the blood circulation
What is clonal expansion?
Once a lymphocyte meets and binds to a foreign antigen, it will undergo clonal expansion and multiply to produce lymphocytes with identical receptors which can also bind to the foreign pathogen
What are the different antibodies secreted by B lymphocytes?
IgG IgM IgA IgE IgD
What are the roles of the different antibodies?
IgM is the first antibody secreted and this activates the complement pathway (destructive cascade)
IgG is secreted next and this takes over from IgM
IgA is then secreted and the function of this is to block pathogen binding
IgE activates mast cells
IgD is not secreted and the function of IgD is unknown
What is the role of mast cells and basophils and how do they differ to each other?
Mast cells and basophils are part of the innate system
When these are activated i.e. by IgE or the complement pathway, they secrete a huge amount of inflammatory mediators
Mast cells are generally in the tissues and basophils are generally in the blood
How are mast cells and basophils activated by IgE?
IgE binds to the mast cells and basophils and is present in the bloodstream in this way SO there is generally not much free IgE in the bloodstream
