It would explain that while the immune system normally defends against pathogens, in allergic reactions, it mistakenly identifies substances like pollen, dust mites, pet dander, mold, certain foods, insect stings, medications, or latex as threats. The chapter would then detail the allergic reaction mechanism, starting with sensitization, where the first exposure leads to the production of IgE antibodies that attach to mast cells. Upon subsequent exposure to the same allergen, this binding triggers the mast cells to release chemicals such as histamine, leading to various symptoms. These symptoms can manifest as skin reactions like hives or eczema, respiratory issues such as sneezing, runny nose, coughing, wheezing, and asthma, eye problems like itching and watering, digestive disturbances in food allergies, and in severe cases, a life-threatening anaphylactic reaction. Common allergic conditions like hay fever, asthma, eczema, food allergies, and insect sting allergies would be discussed. Finally, the chapter would briefly introduce methods for diagnosing allergies, such as skin tests and blood tests, and common management strategies, including allergen avoidance, medications like antihistamines and corticosteroids, and potentially immunotherapy for long-term relief.
Review Questions
Question 1.
Define the term “allergy”.
Ans:
An allergy is an exaggerated or hypersensitive reaction of the immune system to substances that are typically harmless to most people. These substances are called allergens, and when an allergic individual is exposed to them, their immune system mistakenly identifies them as dangerous invaders. This triggers an immune response that can lead to various symptoms, ranging from mild irritation to severe, life-threatening reactions.
Question 2.
Name the inflammatory chemical released by the basophils causing skin reaction and construction of the bronchioles.
Ans:
The inflammatory chemical released by basophils that causes skin reactions (like itching and hives) and constriction of the bronchioles (leading to breathing difficulties) is primarily histamine.
Question 3.
How the allergy causing chemical is naturally removed from the body ?
Ans:
The body employs natural mechanisms to manage allergy-causing chemicals such as histamine. The primary method involves enzymatic degradation, where enzymes like diamine oxidase (DAO), active mainly in the gut and bloodstream, and histamine N-methyltransferase (HNMT), prevalent intracellularly, break down histamine into inactive metabolites. These byproducts are then filtered by the kidneys and eliminated from the body via urine. Additionally, the body has processes to stabilize mast cells and basophils, reducing further histamine release. Certain nutrients, such as Vitamin C and quercetin, may also support histamine breakdown or have antihistamine-like effects. However, during acute allergic reactions, the sheer volume of released histamine can overwhelm these natural removal pathways, necessitating the use of antihistamine medications that block histamine receptors to alleviate symptoms.
4. Match the items given under column I with those given under column II.
column I column II
Ans:
column I column II
Question 5.
Name any three routes of which allergens normally enter in our body.
Ans:
Inhalation: Breathing in airborne allergens like pollen, dust mites, pet dander, and mold spores allows them to contact the respiratory system.
Ingestion: Eating foods containing allergens, such as peanuts, milk, or shellfish, introduces them into the digestive system.
Skin Contact: Direct contact with allergens like latex or certain chemicals can cause a reaction on the skin.
Question 6.
What are allergens ? Name any three allergens.
Ans:
Allergens are typically benign substances that provoke an exaggerated immune response in susceptible individuals. Common examples include pollen (airborne particles from plants), dust mites (microscopic organisms in dust), and pet dander (shed skin from animals).
Question 7.
Name the two tests generally used to diagnose allergy and describe any one of them.
Ans:
Two primary allergy diagnostic tests are the Skin Prick Test (SPT) and the Specific IgE Blood Test.
Skin Prick Test (SPT) Briefly: The skin is marked with various allergen extracts, and a small prick allows the allergen to enter. After approximately 15 to 20 minutes, the test sites are examined. A raised, red, and itchy bump, known as a wheal, signifies a positive allergic reaction to that particular allergen. The size of the wheal correlates with the level of sensitivity.
Question 8.
Which test is mostly favoured for testing allergy, prick test or blood test ? Why ?
Ans:
Skin prick tests (SPT) are often favored over blood tests for initial allergy diagnosis because they are faster, more sensitive for common allergens, cheaper, and provide a direct visual reaction. However, blood tests are preferred for severe skin conditions, medication interference, high anaphylaxis risk, uncooperative patients, or when more detailed allergen component information is needed.
