(Ch. 27.4) Many people are allergic to substances in the environment, such as ragweed pollen, as well as foods, such as peanuts. Which of these statements BEST describes an allergic reaction to one of these substances? (1 point) A. The substance is similar or identical to human antigens, and so it triggers an immune system response. B. The substance invades the body and causes damage to tissues, which triggers an immune system response. C. The substance does not directly harm tissues and is not a pathogen, but nevertheless triggers an inflammatory response. D. The substance invades the body and triggers a response from the respiratory system or digestive system, but not the immune system.

C. The substance does not directly harm tissues and is not a pathogen, but nevertheless triggers an inflammatory response.

Explanation:

When a person is allergic to a substance, his or her immune system recognizes a harmless substance, such as components in food, pollen, or dust, as a treat. As a consequence, it starts an immune response that leads to inflammation. The substance that starts the allergic reaction is called an allergen, and it is not a pathogen because it is not a real threat to the body since it does not infect cells. When the allergen enters the body, it binds to antibodies that are in contact with a special type of cell. These specific cells will release a substance known as histamine. Histamine will produce an inflammatory reaction affecting different tissues in our body. For example, it can make us sneeze, have a running nose, swelling parts of our body, have itchiness and redness, amongst others.

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