The respiratory system is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. In humans and other mammals, the anatomy of a typical respiratory system is the respiratory tract. The tract is divided into an upper and a lower respiratory tract. The upper tract includes the nose, nasal cavities, sinuses, pharynx and the part of the larynx above the vocal folds. The lower tract includes the lower part of the larynx, the trachea, bronchi, bronchioles and the alveoli.
Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible. The diseases can range from mild and self-limiting, such as common cold and allergic rhinitis, to life-threatening entities like bacterial pneumonia, pulmonary embolism, acute asthma and lung cancer. Environmental factors such as pollutants and pollens, virus and bacteria etc. can lead to respiratory diseases such as allergic rhinitis, sinusitis, bronchitis and upper respiratory tract infection.