Asthma comes from the Greek word for panting which makes sense because it causes chronic inflammation in the airways making them narrow and more difficult to breathe through, people with asthma can have asthma exacerbations or asthma attacks which are usually triggered by something in the environment which causes immune cells to generate inflammation in the lungs which can make them even narrower and potentially be life-threatening so if we take a look at the lungs, you’ve got the trachea which branches off into the right and left bronchi and then continues to branch into thousands of bronchioles, in the bronchioles you’ve got the lumen, the mucosa which includes the inner lining of epithelial cells as well as the lamina propria and the submucosa which is where the smooth muscle lives, the molecular pathway that leads to asthma is actually pretty complex but it’s often initiated by an environmental trigger in, often an excessive reaction from type 2 helper cells or th2 cells against specific allergens. Th2 cells are an immune cell subtype which are known to be involved in asthma as well as atopic dermatitis and allergic rhinitis making up what’s called the atopic triad.
What can happen with asthma is allergens from environmental triggers like cigarette smoke are picked up by dendritic cells which present them to th2 cells which produced cytokines like interleukin 4 and interleukin 5 leading to a number of the features of asthma. For example interleukin 4 leads to the production of IgE antibodies which coat mast cells and stimulates them to release granules containing things like histamines leukotrienes and prostaglandins and her looking five on the other hand activates eosinophils which promote an immune response by releasing more cytokines and leukotrienes in this case since IgE antibodies are being produced, this is an example of a type 1 hypersensitivity reaction, this leads to two series of events early on minutes after exposure to the allergen, smooth muscle around the bronchioles store to spasm and there’s increased mucus secretion, this narrows the airways making it difficult to breathe and this is why asthma is considered to be a type of obstructive pulmonary disease, there’s also an increase in vascular permeability and recruitment of additional immune cells from the blood, these immune cells especially eosinophils release chemical mediators that physically damage the endothelium of the lungs, initially these inflammatory changes are completely reversible but over the years, irreversible changes start to take place edema scarring and fibrosis build up leading to thickening of the epithelial basement membrane which permanently reduces the airway diameter although the specific causes of asthma are ultimately unknown, it’s thought to be caused by a combination of genetic and environmental factors since certain genes have been identified that increased the risk of developing asthma and having a family history of asthma seems to increase the risk as well, for environmental factors there’s the hygiene hypothesis which suggests that reduced early immune system exposure to bacteria and viruses might actually increase the risk of later developing asthma possibly by altering the overall proportion of immune cell subtypes in general.
Causes of childhood asthma diagnosed before age 12 are thought to be due to a stronger genetic influence worse later onset as most more likely to be due to environmental factors, now the triggering substance that leads to an asthma attack can differ from person to person but some common ones include air pollution like cigarette, smoke and car exhaust as well as allergens like dust, pet, dander, cockroaches and mold medications like aspirin and beta blockers have also been known to trigger symptoms in some individuals with asthma.
Symptoms of asthma include coughing, a feeling of chest tightness dyspnea or difficulty breathing and wheezing or a high-pitched whistling sound that usually happens during exhalation occasionally in the spin, there might be Kersh min spirals which are spiral shaped mucus plugs or basically elongated mucus casts from the small bronchi of people with bronchial asthma, mucus plugs can be particularly dangerous because they not only block exchange of air but they also block inhaled medications from getting to the site of inflammation, the mucus might also have Charcot Laden crystals which are shaped like needles and are formed by the breakdown of eosinophils, now asthma can be classified according to the frequency of symptoms in particular nighttime, in early morning symptoms the fev1 or forced expiratory volume in one second the PE FR or peak expiratory flow rates both of which measure the amount of obstruction in the airways and finally how often a person is using asthma medication to help with the symptoms from least to most severe. The types of asthma are intermittent asthma, mild persistent asthma, moderate persistent asthma and finally severe persistent asthma, while there’s no cure for asthma, there are treatments available that can help manage the symptoms and prevent the development of an asthma attack, First people with asthma should avoid or minimize contact with triggering substances by vacuuming, removing carpets and rugs and changing the environmental conditions like for example drying out a room in the case of moulds that grow well in moist areas. There are also a number of medications that can reduce the symptoms of asthma bronchodilators like short-acting beta-2 receptors a Guinness tz and anticholinergic medications are often administered through emergency inhalers. These fast-acting medications cause the smooth muscles in the lungs to relax and therefore dilate the airways opening them up so that the person can breathe, individuals with more severe forms of asthma might need additional treatments like daily corticosteroids, long-acting beta audrina scepter agonists or leukotriene antagonists, in very severe cases intravenous corticosteroids magnesium sulfate and oxygen therapy might be needed. So as a quick recap, asthma is characterized by chronic inflammation in the lungs as well as asthma exacerbations or attacks where certain triggers start up more inflammation which leads to smooth muscle spasms in mucus production both of which make it hard to breathe.