A student was visiting a friend at her home. Her friend owned two cats. After playing with the cats for
a while, the student began to sneeze. Her nose began to run and her eyes became red, watery, and
itchy. It also became hard for her to breathe. A few minutes after leaving her friend’s home, the
symptoms disappeared.
Provide a biological explanation for the symptoms the girl developed at her friend’s house. In your
response, be sure to:
• state one reason why her symptoms are not likely due to an infectious agent

The substance that provokes allergy to cats is a protein produced in the sebaceous glands and that can be found in the cats´ hair. It can be found in clothes, walls, beds, among other places. As it can also be suspended in air, a person can easily breathe it. In a house with cats, these proteins are present in important amounts.

An allergic reaction is an abnormal response of the immunity system to a substance considered strange to the body, in this case, the protein or the cat´s hair. These strange substances are called allergens.

The allergen gets in contact with the body for the first time in a sensibilization face. The immunity system considers that this is a strange dangerous substance for the body. In this first stage, the subject submitted to the presence of the allergen does not show any symptoms. But in a second contact, the organism reacts with allergic reactions.

There might appear symptoms in ayes and nose as irritations, stinging, cough, skin´s eruptions and difficulty to breath.