== Overview ==
Asthma is a lung disease that inflames and narrows the airways or bronchial tubes.
Asthma causes periods of wheezing, chest tightness, shortness of breath, and coughing. In an asthmatic person, the muscles of the bronchial tubes tighten and thicken, and the air passages become inflamed and mucus filled, making it difficult to breathe. Factors that trigger asthma are allergens found in dust, animal fur, mold, dustmites, pollen from, grass, and flowers. Other factors are irritants such as cigarette smoke, air pollution, chemicals or dust in the workplace, and sprays such as hairspray also trigger asthma symptoms.All these factors contribute to constriction of our airways.
The airways of the lungs called bronchi (or bronchial tubes), are tubes with muscular walls that contract when irritated. Along the lining of the Bronchi there are cells with microscopic structures called G protein coupled receptors. These G protein coupled receptors are called beta-2 adrenergic receptors and cholinergic receptors. The beta-2 adrenergic receptors respond to chemicals such as epinephrine to make the muscles relax and thus opening the airways and increasing airflow. Cholinergic receptors on the other hand respond to a chemical called acetylcholine making the muscles contract, thereby decreasing airflow.
During an Asthma attack constriction of the Bronchi are caused by abnormal sensitivity of the cholinergic receptors, which cause the muscles of the airways to contract when they should not. There are cells in the Bronchi called mast cells which are held responsible for this cellular response. These mast cells release substances such as histamine and leukotrienes, which activate the cholinergic receptors cellular response for smooth muscle contraction, mucous buildup, and white blood cell migration to certain areas. Eosinophils, a type of white blood cell is found in the airways of asthmatic people, also release substances that contribute to airway constriction.
There’s no cure for asthma, however there are Albuterol inhalers for keeping asthma symptoms in a controlled state. There are several inhalers such as Albuterol, Ventolin and Proventil. Albuterol inhalers also known as a bronchodilater is a quick-relief or rescue medication used to decrease asthma symptoms.
Albuterol is a beta2-adrenergic receptor agonist How albuterol works is that when Albuterol is inhaled to the lungs, it acts on the Beta2-adrenergic receptors which activates the Gs protein. The Gs protein then activates adenylyl cyclase. Adenylyl cyclase then converts ATP to cyclic AMP. Cyclic AMP then activates a protein kinase A which continues the rest of the cyclic AMP pathway.
The pathway is continued until the cell responds by relaxing the smooth muscles in the Bronchi, thus reducing inflammation and allowing oxygen to be inhaled