Why are some people Allergic?

Why are some people allergic? Because they didn’t take my autograph. No. People can be allergic to a wide range of things. Some of the most common ones include milk, peanuts, pollen, shellfish, etc. An allergy occurs. When our immune system mistakenly identifies a normal innocuous substance as a harmful intruder. Hence, it produces antibodies to kill the intruder. And in the process, gives rise to itching, runny nose, watery eyes, etc. Thus causing an allergy. Now, according to hygiene hypothesis, allergies are caused due to clean environments. During childhood, exposure to germs allows our immune system to identify harmful substances. However, if children are kept in extremely clean environments. And not exposed to germs at all, then their immune system fails to develop properly. And instead, starts attacking harmless substances, thus causing an allergy. For example, if such a person inhales some harmless pollen. His nose starts creating extra mucus to trap the pollen, making his nose run. And thus, causing an allergy. Why does sunlight make you sneeze? Because sun teases our nose. No. Wait. I’ll explain. Sneezing caused by sunlight or bright light is called photic sneezing. According to a prevailing theory. It happens because of a thick nerve bundle called the trigeminal nerve. The trigeminal nerve detects or senses irritants in our nose. Thus, triggers sneezing to expel them out. The trigeminal nerve lies quite close to the optic nerve. Which sends visual information from our eyes to the brain. Now, in some people this optic nerve is over sensitive. Just like me, right? Oh. Just listen. When bright light suddenly stimulates the optic nerve. The optic nerve mistakenly transmits some signals to the nearby trigeminal nerve. Hence, the trigeminal nerve misinterprets this signal as an irritant in the nose. And thus, triggers sneezing. How to stop a sneeze? By saying Cheese. Oh dude. At least once think of a sensible answer. A sneeze is controlled by the trigeminal nerve present in our face. When irritants like dust and pollen enter our nose. The trigeminal nerve triggers sneezing to expel them out with huge force and pressure. Now, many people close their nostrils and mouth to stop a sneeze. But this can lead to transfer of force and pressure inside their heads. Thus damaging their eardrums or other tissues. Normally, sneeze should not be stopped. But in exceptional situations. A relatively safe way to stop a sneeze is to press our finger above our upper lip. Since the trigeminal nerve is also present above our upper lip. Such pressing action also sends a signal through that nerve to the brain. This interrupts the sneeze response and distracts the brain. Thus helping in stopping our sneeze. What is an allergy? It is a magic spell. No. Allergy is an overreaction of our immune system to usually harmless substances. Like peanuts, milk, pollen, etc. These substances are called allergens. Our immune system has white blood cells or lymphocytes. Which protect us from foreign invaders such as bacteria, viruses, parasites, etc. These invaders are called antigens. When a lymphocyte detects an antigen, it produces antibodies. Antibodies destroy antigens and thus, protect us. Now, if an allergen such as pollen is inhaled by an allergic person. The lymphocytes of the allergic person for unknown reasons think that the allergen is an antigen. Hence, lymphocytes overreact and produce antibodies which start attacking the allergen. Besides this, as a protective response. Some immune cells also trigger production of excess mucus. Resulting in running nose. They even give rise to itching throat and watery eyes. Thus causing an allergy.