1. Allergies

2. Allergies/Hypersensitivity
Immune System overreacts to the presence of a harmless antigen causing tissue damge
Tend to get worse with each exposure

3. Immediate/Acute Hypersensitivity
Most common
Triggered by the release of histamine
Histamine causes capillaries to become dilated and leaky, and the release of mucus
Common symptoms – runny nose, watery eyes, itching, hives

5. Anaphylactic shock Body-wide acute allergic response Fairly rare
Occurs when allergen directly enters blood and circulates throughout body
Swelling can block airways
Epinephrine reverses symptoms (constricts blood vessels)
Ex. Bee sting, spider bite injections

6. Delayed Hypersensitivities
Occur about 1 – 3 days after exposure
Involve the release of lymphokines instead of histmines
Usually presents as dermatitis
Ex. Poison ivy