The upper respiratory tract consists of the nose, the sinuses, and the pharynx. The pharynx has a large number of lymph gland distributed around, the important ones being the adenoids and the tonsils. The diseases encountered in this are viral or bacterial infections. These lymph glands do a very efficient job of arresting bacteria and viruses and get inflamed.

Nose is the first organ the incoming air encounters. The hair in the nose filters out gross impurities.

Pharyngitis is the inflammation of the lymphatic glands there. The important ones are adenoids and tonsils. Severe cases one has to undergo their surgical removal.

The lower respiratory tract diseases are diseases affecting the organs below the level of the larynx. These are basically the diseases of the larynx, laryngitis, the bronchi, bronchitis, the alveoli, and the lung.

Emphysema is the collapse of the alveoli. Chronic irritation of the bronchioles causes restriction of air and secretion of mucus. Coughing, an attempt to clear the airways follows. Heavy cough results in considerable pressure in the alveoli which can rupture its thin walls. This leads to two important consequences. The direct is a loss of gas transfer area resulting in oxygen starvation in the body. The loss of elastic fibers impedes the spring back of the lungs to expel the air. The treatment consists of removing the sources of irritant, promoting the removal of the bronchial secretions and use of antibiotic to prevent infections. Patients are retrained to breathe in ways that maximize expiration.

Asthma is the periodic contraction of the smooth muscles of the bronchi restricting air movement. In many of the cases, this is in response to some allergen. The treatment in such cases is to find out the exact allergen and avoid their inhalation or desensitizing the individual to them.

Administration of vasodilators helps dilate the bronchi. An expectorant helps clear the mucus.