Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

The Study of Internal Organs (Splanchnology)
Respiratory System

The Respiratory system delivers oxygen (O2) to the body and removes carbon dioxide (CO2). It consists of the respiratory tract (airways) and paired respiratory Organs—the Lungs (Fig. 54). Depending on their Location, the airways are divided into the upper and lower respiratory tracts. The Upper Respiratory Tract includes the Nasal cavity, as well as the nasal and oral PARTS OF THE Pharynx. The Lower Respiratory Tract comprises the Larynx, Trachea, and Bronchi. As air passes through the airways, it is warmed, moistened, and filtered of foreign particles. Gas exchange between the inhaled air and the Blood takes place in the lungs. Oxygen diffuses from the pulmonary alveoli into the blood of the pulmonary capillaries, while carbon dioxide moves in the opposite direction, passing from the blood into the alveoli.

The walls of the airways are supported either by a bony Skeleton, as in the nasal cavity, or by Cartilage (larynx, trachea, bronchi). As a result, the airway lumen remains constantly open, preventing the walls of these organs from collapsing. The mucous membrane of the airways is lined with ciliated epithelium and kept moist. The beating cilia of the epithelial Cells sweep out trapped foreign particles along with mucus.



Last update: 10/08/2026

Editorial and Educational Adaptation: This material has been compiled based on the primary/original source text. The project team performed an editorial review, corrected technical inaccuracies, structured sections, and adapted the content for an educational format.

What was processed:

  • elimination of formatting defects (OCR errors, structural breaks, corrupted characters);
  • editorial organization of content;
  • standardization of terminology in accordance with academic sources;
  • verification of factual statements against the original source text.

All mentions of the author, publication year, and origin of the primary text have been preserved in accordance with the source.