Upper Portion of the Respiratory Tract ‒ Section

Both respiratory rate and depth are controlled by the respiratory centers of the brain, which are stimulated by factors such as chemical and pH changes in the blood. These changes are sensed by central chemoreceptors, which are located in the brain, and peripheral chemoreceptors, which are located in the aortic arch and carotid arteries. The floor of the nasal cavity is composed of the palate. The hard palate at the anterior region of the nasal cavity is composed of bone. The soft palate at the posterior portion of the nasal cavity consists of muscle tissue. Several bones that help form the walls of the nasal cavity have air-containing spaces called the paranasal sinuses, which serve to warm and humidify incoming air. Each paranasal sinus is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal sinus. The sinuses produce mucus and lighten the weight of the skull. The uvula is a small bulbous, teardrop-shaped structure located at the apex of the soft palate. Both the uvula and soft palate move like a pendulum during swallowing, swinging upward to close off the nasopharynx to prevent ingested materials from entering the nasal cavity. An olfactory epithelium used to detect odors is found deeper in the nasal cavity. The nasopharynx is flanked by the conchae of the nasal cavity, and it serves only as an airway. At the top of the nasopharynx are the pharyngeal tonsils.



*LICENSES AND ATTRIBUTIONS

CC licensed content, Shared previously, The Process of Breathing, Authored by: OpenStax College. License: CC BY: Attribution. License Terms: Download for free at http://cnx.org/contents/AQNhNZty@1.1:u67b9E14@6/The-Process-of-Breathing*

## Keywords
section of the upper airways, nose, nasal cavity pharynx nasopharynx