Allergy - ENT Flashcards
What are examples of allergies?
Asthma (9.4%)
Allergic rhinitis (5.4%)
Eczema (1%)
Food allergies (1-2%)
Is the incidence of allergies increasing or decreasing?
Increasing since the 1960s
Is the incidence of allergies greater in developed or developing countries?
Developed
What are some risk factors for allergies?
Heredity
Race
Age
Environment (alterations in exposure to infectious disease during early childhood, environmental pollution, allergen levels, dietary changes)
Occupational (flour, latex, wood dust)
What is an allergy?
Hypersensitive disorder of the immune system
What does an allergy occur in response to?
Normally harmless environmental substances, known as allergens
What is an allergen?
Antigen that causes allergic reaction
What are allergens normally?
Proteins
What are examples of skin allergies?
Urticaria/angiodema
What is an example of an upper respiratory allergy?
Rhinitis
What is an example of a lower respiratory allergy?
Asthma
What is an example of a systemic allergy?
Anaphylaxis
What is the pathophysiology of a type 1/immediate hypersensitive reaction?
1) Sensitisation (plasma cells produce IgE which bind to mast cells)
2) Re-exposure (mast cells degranulate)
What do mast cells release when they degranulate?
Histamine
Leukotriences
Prostaglandins
Chemotactic agents
What effect does degranulation of mast cells have?
Vasodilation
Vascular permeability
Smooth muscle contraction
Leukocyte infiltration, especially eosinophils
What are the 2 phases of an allergic response?
Acute response
Late response
What is the process of the acute allergic response?
1) Exposure to antigen
2) Antigen specific IgE
3) Degranulation of mast cells causing systemic effects
When does the late phase of the allergic response occur?
2-4 hours after exposure
Why is there a late phase to allergic reactions?
Due to migration of other leukocytes such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site
What are symptoms of the inflammatory response due to the late phase of allergic reaction?
Sneezing
Coughing
Wheezing
Runny nose
Weepy eyes
Itchiness
What is allergic rhinitis?
Allergic inflammation of the nasal airways