Anatomy & Physiology

Anatomy & Physiology Study Guide Located outside the thoracic cavity, the upper respiratory system consists of the nose, nasal cavity, paranasal sinuses, and pharynx: • The components of the upper respiratory system consist of the nose, nasal cavity, paranasal sinuses, and pharynx. • Air enters the respiratory system through the external nares, which open into the nasal cavity. The nasal vestibule (entryway) is protected by hairs that screen out large particles. • Incoming air flows through the superior, middle, and inferior meatuses (narrow grooves) and bounces off the conchal surfaces. • The hard palate separates the oral and nasal cavities. The soft palate separates the superior nasopharynx from the rest of the pharynx. The connections between the nasal cavity and nasopharynx are the internal nares. • The nasal mucosa traps particles, warms and humidifies incoming air, and cools and dehumidifies the outgoing air. • The pharynx is a chamber shared by the digestive and respiratory systems. The nasopharynx is the superior part of the pharynx. The oropharynx is continued down through the oral cavity. Next is the laryngopharynx, which is the narrow zone between the hyoid bone and the entrance to the esophagus. The larynx, consisting of cartilages, ligaments, and muscles, produces sound: • Inhaled air passes through the glottis in route to the lungs; the larynx surrounds and protects the glottis. • Three large cartilages (the thyroid cartilage, cricoid cartilage, and epiglottis) and three smaller pairs of cartilages (the arytenoid, corniculate, and cuneiform cartilages) make up the cylindrical larynx. The epiglottis projects into the pharynx. • Two pairs of folds span the glottis: the inelastic vestibular folds and the more delicate vocal folds. • Sound is produced when air passes through the glottis and vibrates the vocal folds. The diameter, length, and tension of the vocal folds dictate the pitch of the sound. • The larynx is stabilized by the muscles of the neck. The tension in the vocal folds or the opening and closing of the glottis is regulated by the smaller intrinsic muscles. However, both sets of muscles prevent particles from entering the glottis during swallowing. The trachea and primary bronchi convey air to and from the lungs: • The right and left primary bronchi are formed by trachea branches within the mediastinum. • Each bronchus enters a lung at the hilum (a groove). The root is a connective tissue mass that includes the bronchus, pulmonary vessels, and nerves. • The trachea extends from the sixth cervical vertebra to the fifth thoracic vertebra. The submucosa contains C-shaped tracheal cartilages, which stiffen the tracheal walls and protect the airway. The posterior tracheal wall can distort to permit large masses of food to pass through the esophagus. Achieve Page 309 of 368 ©2018