Asthma provokes narrowing of the airways and this interferes with normal in and out air movements of the lungs. Asthma generally involves bronchial tubes and it doesn’t affect lung tissues and air sacs. The narrowing which happens in people with asthma is generally provoked by 3 main conditions: bronchospasm, hyperreactivity and inflammation.
Bronchospasm
The muscles found around bronchial tubes normally tighten during asthma attacks. The muscle constriction in the airways is named bronchospasm. Actually bronchospasm evolves further narrowing of the airways. Nerves and chemical mediators present in bronchial tubes make the muscles constrict. Bronchospasms generally happen in all people and they can be acquired through inhaling dry and cold air.
Hyperreactivity
In people who suffer from asthma, chronically constricted and inflamed airways become very sensitive, or in other words reactive, to such triggers as infections, irritants and allergens. Being exposed to the triggers can step by step lead to further narrowing and inflammation.
Inflammation
Actually the most important condition that evolves the narrowing of bronchial tubes is without any doubts inflammation. First bronchial tubes begin to red, they are also swollen and irritated. The inflammation adds to the wall thickness in bronchial tubes. This leads to a really small passageway for the air to flow in and out. We should say that this inflammation happens as a reaction to an irritant or an allergen and is actually the result of chemical mediators action (leukotrienes, histamine, etc). The tissues inflamed release an extra amount of so to say sticky mucus in the tubes. Then the mucus clump together thus forming plugs which may clog smaller airways. Some specialized inflammation and allergy cells (such as white blood cells and eosinophils) that generally accumulate at the site, provoke the damage of tissues. The damaged cells are normally shed into the body airways, in such a way adding to the narrowing.
The combination of the mentioned above three factors make it difficult to breathe out, or so to say to exhale. The air is to be exhaled forcefully to overcome this narrowing, thus evolving typical sound of wheezing. Individuals who suffer from asthma frequently cough trying to expel those thick plugs of mucus. Decreasing the air flow might lead to less oxygen getting into the bloodstreams. In case it is really serious, carbon dioxide can accumulate into the blood.