Asthma is a recurring health condition that affects your body's ability to move air in and out of your lungs. Things that irritate the airways and cause them to narrow (such as pollen, smoke, or dust) are known to trigger the condition. These triggers can lead to an asthma attack, which includes symptoms such as wheezing and difficulty breathing. Anyone with possible symptoms should see a doctor to develop an appropriate treatment plan and learn how to avoid potential triggers.
What Is Asthma ?
Asthma is a chronic disease that affects your airways, which are the tubes that carry air into and out of your lungs. If you have asthma, the inside walls of your airways are inflamed (swollen). The inflammation makes the airways very sensitive, and they tend to react strongly to things that you are allergic to or find irritating. When the airways react, they get narrower and less air flows to your lung tissues. This causes symptoms like wheezing (a whistling sound when you breathe), coughing, tightness in the chest, and trouble breathing.
What Is an Asthma Attack ?
When you experience a worsening of your symptoms, it is called an asthma episode or attack. In an asthma attack, muscles around the airways tighten up, making the airway openings narrower so less air flows through. Inflammation increases, and the airways become more swollen and narrow. During an attack, cells in the airways also make more mucus than usual, which further narrows the airways. These changes cause the symptoms of asthma and make it harder to breathe. Asthma attacks are not all the same -- some are worse than others. In a severe attack, the airways can close so much that not enough oxygen gets to vital organs. If this happens, immediate medical attention is needed. People have even died from severe asthma attacks.
Sources http://asthma.emedtv.com