Allergies Genetic or Environmental?
In the past few years many studies have been conducted which confirm that allergies are hereditary. These studies show that genes play a role in allergy development. The question remains whether these genes are inherited from each parent or if they develop during fetal life. Some scientists believe that allergies are environmental in origin while others think that allergies are genetically based.
There is no doubt that allergies are inherited but what does it mean when someone says that their child has allergies because of allergies genes? What exactly are those genes? How did they get into our bodies?
The Second Nervous System
The nose is a sensory organ and it has its own nervous system. Allergies are a response of this nervous system. The nose sends messages to the brain about smells. We can smell things because of our nose and our brain.
If the nose is injured or has a cold, then we do not smell things as well and that is because of the way that our brain processes information from our nose. Allergies happen when our nose is injured in a different way. When we smell something that is in the air, such as dust or pollen, the molecules of that thing set off a chain reaction inside the nose. Specialized cells begin to release chemicals such as histamine. These chemicals cause blood vessels inside the nose to become swollen and leaky. The body notices this change and prepares itself to fight off infection. It does this because it has not developed a tolerance for these foreign molecules. In this case, it was something that was already inside the body. This is known as an ‘allergic reaction.’
The chain reaction inside the nose is not complete without mast cells and basophils. These cells are usually activated by the presence of certain types of parasites or bacteria inside the body. When dust mites or pollen is floating around inside the nose, these cells do not recognize them as foreign invaders. They release histamine just like they would against infection.
The result is a runny nose and itchy eyes. When the body begins to react to regular things that are in the air, it is known as hay fever. Hay fever is just one of several allergic diseases.
Allergies and Genetics
Why do some people develop allergies and other don’t?
There are several things that determine whether a person will become allergic or not. One of these factors is the genes that people receive from their parents. If a person receives certain types of genes then they are more likely to become allergic to certain things. Even if both parents have allergies, they may not necessarily pass them on to their children. If a child does inherit allergies, they may become allergic to different things than their parents are.
The second factor is how well the body develops tolerance to different things. The body can sometimes become tolerant of things that are always present. This is called ‘acquired tolerance.’ Some people are just more likely to develop an acquired tolerance than others.
When a person has an acquired tolerance to something, they are less likely to react to it, even if they have inherited allergies. The risk of severe reactions is still there though.
The final factor is the environment in which a person lives. People who grow up in rural areas are less likely to become allergic to things than people who grow up in cities. This is probably because there are more things growing and living outdoors in rural areas. Developed countries have much more indoor pollution than developing countries.
This is because in developed countries, people heat and cool their homes using energy from fossil fuels. This changes the air and makes it less healthy to breathe in.
Allergies and Your Immune System
Immune system cells are either innate or adaptive. Innate cells are present from birth and work immediately to fight off infection. These cells include the blood cells, macrophages, natural killer cells and neutrophils. Adaptive cells develop after birth.
These include the T-cells, B-cells and other cells of the immune system. The reaction to allergens is an example of a response from the adaptive immune system.
When a person is allergic to something, their body treats it as an invader even though it is not. This is because the immune cells remember previous invasions. When they see invaders that are similar, they respond quickly without having to be reminded by the adaptive immune system. The type of immune response is determined by the type of allergic reaction.
Types of Allergic Reactions
The most common types of allergic reactions are hay fever, hives, asthma and anaphylaxis.
Hay fever, also known as allergic rhinitis, is an allergic reaction of the membranes of the nose. This can cause a runny nose, post-nasal drip and sometimes even a cough. Hay fever is caused by allergens such as pollen, dust and mold.
Hives, also known as urticaria, is an itchy rash that appears on the skin. It is caused by histamine and other chemicals released by immune cells. The itchy rash can range in size from tiny spots to large areas of swollen, red skin. Hives appears suddenly and may disappear just as suddenly.
Asthmatics have trouble breathing because their airways become inflamed and filled with mucus. The swelling of the airways makes it difficult to breathe. In an asthma attack, the airways become completely blocked. This causes the person to breath rapidly or stop breathing altogether.
Anaphylaxis is the worst type of allergic reaction. In an anaphylactic shock, the whole body reacts to a foreign substance. The most well-known symptoms of anaphylaxis are a drop in blood pressure and a drop in heart rate. These can quickly lead to death if not treated immediately.
Anaphylactic shock is caused by allergens such as insect venom or medication.
There are several different types of treatment for allergies. These range from avoidance of allergens to surgery.
The first step in treating allergies is the simplest. If you know what is causing your allergic reaction, you can simply avoid it.
Avoiding allergens can be difficult if you work with the allergen every day. For example, a person who works on a farm may need to find a new job. A teacher with a classroom full of cats may need to move to a different school or switch classes in the middle of the year.
Allergies can also be treated with medication. The most common is antihistamines. Antihistamines block the action of excess histamine in the body. This reduces swelling and decreases mucus production.
Another medication is montelukast. This drug blocks the release of leukotrienes, another substance involved in inflammation.
Systemic corticosteroids may also be given to people with allergies. These drugs suppress the whole immune system and are only used in extreme cases.
A less common treatment is allergy shots. Allergy shots, also called immunotherapy, gradually increase a person’s resistance to allergens. The process involves getting a small amount of an allergen and increasing the dose over time. This desensitizes the immune system.
A newer treatment involves stem cell therapy. This process is still experimental, but in some cases it has been successful. Stem cells are injected into the body. They produce a protein called interleukin-10.
This protein decreases allergic reactions.
A less common, but permanent, treatment for allergies is immunotherapy. This treatment involves getting shots of an allergen. These injections slowly build up the body’s resistance to the allergen. Within a few years, a patient can handle much larger doses of the allergen.
In severe cases, an allergy sufferer may choose to undergo desensitization immunotherapy. During this process, a patient is given increasing doses of an allergen until the immune system no longer reacts. The benefits are immediate. The process can take a few months.
The long-term effects of desensitization immunotherapy are unknown. This process was once performed on people with deadly peanut allergies. After the treatment, these people could safely eat peanuts. However, this treatment is no longer available because someone died from an allergic reaction.
Allergies play an important role in the human body’s immune system. However, some people suffer from allergies without any benefit. Others have little choice but to live with their allergies. In these cases, a combination of avoidance, medication, and immunotherapy can help allergy sufferers lead normal lives.
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