Asthma (Hen Suyễn)

  To understand asthma, it helps to know how the airways (đường thở) work. The airways are tubes that carry (mang, đem) air into and out of your lungs. People who have asthma have inflamed airways. The inflammation makes the airways swollen (sưng lên) and very sensitive (nhạy cảm). The airways tend (có xu hướng) to react (phản ứng) strongly to certain inhaled substances. When the airways react, the muscles around (xung quanh) them tighten (thắt chặt). This narrows (thu hẹp) the airways, causing less air to flow (lưu lượng) into the lungs. The swelling also can worsen (xấu đi), making the airways even narrower. Cell in the airways might make more mucus (chất nhầy) than usual. Mucus is a sticky (dính), thick liquid that can further narrow the airways. This chain reaction (phản ứng dây chuyền) can result in asthma symptoms. Symptoms can happen each time the airways are inflamed.