What is Asthma?
Asthma comes from the greek word panting, which make sense because it cause chronic inflammation of the airways making them narrow and making them to difficult to breath through. People with asthma can have asthma exarcerbation or asthma attack, which are usually trigger by something in the environment which causes the immune cells to generate inflammation in the lungs which can make them even narrower and potentially make them life threatening.
So if we try to take a look at the lungs you got the trachea, which branches out into the right and left bronchi and then continues to branch into a thousand of bronchioles. In the bronchioles you’ve got the lumen, the mucosa which include the inner lining of the epithelial cells as well as the lamina propria and the sub mocusa which where the smooth muscle lives. The molecular pathway that leads to asthma is actually pretty complex, but its oftenly initiated by the environmental triggers.
In asthma there are often an excessive reaction from type 2 helper cells or Th2 cells against specific allergens. Th2 cells are immune cell subtypes, which are known to be involves in asthma as well as atopic dermatitis and allergic rhinitis, making up with called the atopic triad.
What can happen with asthma is allergen from environmental triggers like cigarettes smoke, are pickup by dentritic cells which present them with Th2 cells, which produces cytokines like interleukin 4 and interleukin 5 leading a number of feature of asthma, for example interleukin 4 leads the production of IgE antibodies, which co mast cells and stimulate them to release granules containing thing like histamine, leukotrienes and prostaglandins. Interleukin 5 on the other hands activates eosinophils which promotes an immune response by releasing more cytokines and leukotrienes.
In this case since IgE antibodies are being produced, this is an example of type 1 hypersensitivity reaction, this leads to two series of events. Early on, minutes after exposure to the allergens smooth muscle around the bronchioles starts to spasm, and theirs an increase of mucus secretion, this narrows the airways making them difficult to breathe and this is why asthma is a type of chronic obstructive pulmonary disease. There’s also an increase of vascular permeability and recruitment of additional immune cells from the blood. This immune cells especially eosinophils release chemical mediators that physically damage the endothelium of the lungs. Additionally, this inflammable changes are completely irreversible, but over the years irreversible changes start take place, edema, scarring and fibrosis build up, leading to thickening of the epithelial basement membrane which permanently reduces the airways diameter.
Cause of Asthma
Although, specific causes of asthma or ultimately unknown is thought to be cause by a combination of genetic and environmental factors, since certain genes have been identified that increase of risk developing asthma and having a family history of asthma seems to increase the risk as well.
For environmental factors there is the hygene hypothesis, which suggest that reduced early immune system exposure to bacteria and viruses might actually increase the risk of later development of asthma. Possible by altering the overall proportion of immune cell sub types. In general causes of childhood asthma diagnose before age 12, are thought to be due to a stronger genetic influence where later onset asthma is more like due to environmental factors.
Triggering Substances of Asthma
The triggering substance that leads to asthma attacks in different from person to person, is common once like air pollution like cigarette smoke and car exhaust, as well as allergens like dust, pet tender, cockroaches and molds. Medication like aspirin and beta blockers are also been known to trigger the symptom in some individuals with asthma.
Symptoms of Asthma
Symptoms of asthma is coughing, a feeling of chest tightening, dyspnea or difficulty in breathing and wheezing or a high pitch whistling sounds that usually happens during exhalation. Occasionally in the sputum there might be a curschmann spirals, which are spiral shape mucus plugs or basically an elongated mucus casts from the small bronchi of people with bronchial asthma. Mucus plugs can be particularly dangerous because they not only block the exchange of air, but they also block the inhaled medication from getting the side of inflammation. The mucus might also have charcot-leyden crystals, which are shape like needles and are form by the breakdown of eosinophils.
Asthma Classifications of Symptoms
Asthma can be classified according to the frequency of symptoms in particularly night time and in early morning symptoms. The FEV1 or the force expiratory volume in 1 seconds, the PEFR or peak expiratory flow rate, both of which is measured the amount of obstruction in the airways and finally how often the person is using asthma medication to help with the symptoms.
Types of Asthma
From least to most severe the types of asthma are intermittent asthma, mild persistent asthma, moderate persistent asthma and finally severe persistent asthma.
Treatment of Asthma
While there is no cure for asthma, there are treatment available that can help manage the symptoms and that can prevent the development of the asthma attack. First people with asthma should avoid or minimize contact with triggering substances by vacuuming, removing carpet and rugs, and changing the environmental conditions, like for example dying out the rooms in the case of the molds, that grow out in the moist areas.
There are also number of medication that can reduce the symptoms of asthma. Bronchodilators like short-acting beta adrenocepter agonists and anticholinergies medications are often administered through emergency inhalers. These fast acting medications causes smooth muscle in the lungs to relax, and therefor dilate the airways, opening them up so that the person can breathe.
Individuals with have more severe form asthma might need of additional treatment, like daily corticoid steroids, long acting beta-adrenoceptor agonists or leukotriene antagonists.
In very severe cases, intevenous corticosteroids, magnesium sulfate and oxygen therapy might be needed.
Asthma is characterized by a chronic inflammation in the lungs, as well as asthma exacerbations or attacks, or certain triggers start up more inflammation which lead to smooth muscle spasm and mucus production both of which make it harder to breathe.
