molecular energy level. (physical chemistry). One of the states of motion of nuclei and electrons in a molecule, having a definite energy, which is allowed by quantum mechanics.1  Facebook.olecular energy level. (physical chemistry). One of the states of motion of nuclei and electrons in a molecule, having a definite energy, which is allowed by quantum mechanics. 1  Facebook.
Air first enters your body through your nose or mouth, which wets and warms the air. (Cold, dry air can irritate your lungs.) The air then travels through your voice box and down your windpipe. The windpipe splits into two bronchial tubes that enter your lungs.
Asthma is a chronic disease that affects the airways that carry oxygen in and out of the lungs. If a person has asthma, the inside of these airways is irritated and swollen. Asthma can cause shortness of breath, wheezing, coughing, and tightness in the chest. Asthma is a major chronic health problem for children.