1. Respiratory System The respiratory system consist of the nose, pharynx (Throat), Larynx (Voice Box) trachea (Wind pipe), bronchi, and lungs. It’s part can be classified according to either structure or function. Structurally, the respiratory system consist of two part: The upper respiratory system includes, the nose, phanynx, and associated structures The lower respiratory systems include the larynx, trachea, bronchi, and lungs Functions Functionally, the respiratory system also consists of two parts 1. The conducting zone, consists of a series of interconnecting cavities and tubes both outside and within the lungs, the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles filter warm, and moisten air and conduct it into lungs. 2. The respiratory zone, consists of tissues within the lungs where gas exchange occurs. The respiratory bronchioles, alveolar ducts , alveolar sacs, and alveoli, the main sites of gas exchange between the blood.

2. The organs of the respiratory system are responsible for bringing fresh air into the lungs, exchanging oxygen for carbon dioxide between the air sacs of the lungs and the blood steam and exhaling the stale air. The Nose: can be divided into external and internal portions. The external nose consist of a supporting frame work of bone and hyalin catilage covered withmuscle and skin and lined by muscous membrane. The frontal bone, nasal bones, and maxillae form the bony framework of the external nose. The internal nose is a large cavity in the anterior aspect of the skull that lies inferior to the nasal bone and superior to the month, it is lined with muscle and mucous membrane. The Pharynx: The pharynx on throat, is a funnel-shapped tube about 13 cm (5in) long that starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx.

3. The Larynx: Larynx or voice box is a short passageway that connects the laryngopharynx with the trachea. It lies in in the midline of the neck anterior to the esophadus and the forth through sixth cervial vertebrea. The Trachea: Trachea or windpipe, is a tubular passageway for air that is about 12cm (5in) long and 2.5cm (1 in) in diameter. The Bronchi: At the superior border of the fifty thoracic vertebra, the trachea divides into a right lung, and a left primary bronchus, which goes into the left lung. The Lungs: the lungs are lightweight, because they float. They are paired cone-shape organs in the Thoracic cavity. They are separated from each other by the heart and other structures in the mediastium, which divides the thoracic cavity into two anatomically district chambers

4. Source: www.wiley.com/college/tortora Medical terminology A living language