Topic 4: Malfunctions of the Immune system Flashcards
What is an allergen? Give examples.
An allergy is an overreaction by your immune system to a harmless substance.
Example: Pet-hair, pollen, shellfish, nuts
What cells are responsible for an allergic reaction?
Mast Cells and to a smaller degree, Basophils
allergic reaction in first exposure to an
allergen.
- B cells are activated to make IgE antibodies against the allergen
- antibodies bind to mast cells and the person becomes sensitized.
- No symptoms occur
allergic reaction in second exposure to an
allergen
- allergen re-enters and binds to the IgE antibodies on the surface of the mast cell.
- causes the mast cell to release its histamine which leads to inflammation and symptoms follow
List some symptoms of an allergic reaction.
Nausea
rashes
swelling
difficulty breathing
vomitting
Explain how antihistamines help in reducing an allergic reaction.
antihistamines bind to the receptors on blood vessels blocking the histamine from causing inflammation
What is anaphylaxis?
A severe allergic reaction
What chemical is found in an epipen and how does it help during an anaphylactic attack?
Adrenaline - it counteracts the effects of hitamine
- blood vessel to constrict, helps to reduce swelling and increase vlood pressure
- broncodilation: relaxes the muscles around the airways
- - stabilises mast cells and basophils, reducing futher release of histamine
What does it mean if a person is sensitised?
a person’s immune system has been exposed to a specific antigen and has developed an immune response to it
What happens to B cell in first exposure
when an allergen enters it causes the B cell to divide and produce specific IgE antibodies to the allergen.
- IgE antibodies then bind to the mast cell and cause it to be sensitised.
What happens in an autoimmune diseases? Which cells are responsible?
the body’s immune system fails to recognise self antigens and mounts an
attack against its own tissues.
- cytotoxic T cells and Natural killer cells.
