1. List and describe the structures of the upper respiratory tract. 2. List and describe the structures of the lower respiratory tract. 3. Explain what occurs during inhalation and exhalation. 4. Explain the difference between external respiration and internal respiration. 5. Explain how respiration is regulated by the brain. 6. Identify factors that influence breathing. 7. Describe ways in which the aging of an individual affects the respiratory system. The conducting passages are divided into the upper respiratory tract and the lower respiratory tract (Figure 13-1). The upper respiratory tract includes the nose, pharynx, and larynx. The lower respiratory tract consists of the trachea, bronchial tree, and lungs. These passageways open to the outside and are lined with mucous membrane. In some regions the membrane has hairs that help filter the air. Other regions have cilia to propel mucus. The interior chamber of the nose is the nasal cavity (Figure 13-2). It is divided into two parts by the nasal septum. Air enters the nasal cavity from the outside through two openings—the nostrils, or external nares (NAY-reez). The openings from the nasal cavity into the pharynx are the internal nares. The palate forms the floor of the nasal cavity and separates the nasal cavity from the oral cavity. The anterior portion of the palate is called the hard palate because it is supported by bone. The posterior portion has no bony support, so it is called the soft palate. The soft palate terminates in a projection called the uvula (YOO-vyoo-lah), which helps direct food into the oropharynx. Nasal conchae (KONG-kee) are bony ridges that project into the nasal cavity (see Figure 13-2). The three nasal conchae increase the surface area of the nasal cavity to warm and moisten the air. They also help direct air flow through the nasal cavity. Dust and other particles in the air tend to become trapped in the mucous membrane around the nasal conchae. Highlight on the Respiratory System Rhinitis: Rhinitis is an inflammation of the nasal mucosa accompanied by excessive production of mucus. It can be caused by cold viruses, certain bacteria, and allergens. Pharyngitis and laryngitis: Inflammation of the pharynx, or a sore throat, is pharyngitis. Inflammation of the vocal cords is laryngitis. The inflammation may be caused by overuse of the voice, infection with bacteria or viruses, or inhalation of irritating particles. Laryngitis results in hoarseness or an inability to speak above a whisper. Tracheotomy: A tracheotomy is the creation of an opening into the trachea through the neck and insertion of a tube to facilitate passage of air or removal of secretions. Respiratory obstruction: Foreign objects that become lodged in the larynx or trachea are usually expelled by coughing. If a person cannot speak or make a sound because of the obstruction, it means that the airway is completely blocked. This is a life-threatening situation. The Heimlich maneuver is a procedure in which the air in the person’s own lungs is used to forcefully expel the object. Bronchoscopy: Bronchoscopy is a procedure in which a fiberoptic bundle is inserted into the trachea and directed along the conducting passageways to the smaller bronchi. This allows direct visualization of the inside of the bronchi and collection of specimens for cytologic and bacterial studies. Asthma: Several different forms of asthma exist, all of which have sensitive conducting passages. In many cases the agent that triggers the attack is an allergen in the air. The most obvious and dangerous symptom involves the constriction of the smooth muscle around the bronchial tree. The airways become narrow and breathing is difficult. Treatment includes the use of bronchodilators to dilate the respiratory passages to permit airflow. Pleurisy: Pleuritis, or pleurisy, is an inflammation of the pleura and is often painful because the sensory nerves in the parietal pleura are irritated. As the condition progresses, the permeability of the membrane changes, which results in an accumulation of fluid in the pleural cavity, making breathing difficult. Pneumothorax: The accumulation of air in the pleural cavity is called pneumothorax. This condition can occur in pulmonary disease, such as emphysema, carcinoma, tuberculosis, or lung abscesses, when rupture of a lesion allows air to escape from the alveoli into the pleural cavity. It also may follow trauma in which the chest wall is perforated and atmospheric air enters the cavity. Surfactant: Surfactant is not produced until the late stages of fetal life. Newborns who are born prematurely may not have enough surfactant, and the forces of surface tension collapse the alveoli. The newborn must reinflate the alveoli with each breath, which requires tremendous energy. The lack of surfactant accounts for many of the signs and symptoms of infant respiratory distress syndrome (IRDS). The condition is treated by using positive-pressure respirators that maintain pressure within the alveoli to keep them inflated. Highlight on Conditions Affecting the Respiratory System Atelectasis (at-eh-LECK-tah-sis) Collapse of the alveoli; the lung is airless Bronchogenic carcinoma (brong-koh-JEN-ik kar-sin-OH-mah) Cancerous tumors arising from a bronchus; lung cancer; smoking is the primary etiologic agent; spreads readily to the liver, brain, and bones Chronic obstructive pulmonary disease (COPD) (KRAHN-ik ob-STRUCK-tiv PULL-mon-air-ee dih-ZEEZ) A chronic condition of obstructed airflow through the bronchial tubes and lungs, usually accompanied by dyspnea; includes emphysema and chronic bronchitis Coryza (koh-RYE-zah) The common cold, characterized by sneezing, nasal discharge, coughing, and malaise; caused by a rhinovirus Croup (KROOP) Acute respiratory syndrome in infants and children, characterized by obstruction of the larynx, barking cough, and strained, high-pitched, noisy breathing Hemoptysis (hee-MAHP-tih-sis) Spitting of blood as a result of bleeding from any part of the respiratory tract Pertussis (per-TUSS-is) Whooping cough; a highly contagious bacterial infection of the pharynx, larynx, and trachea; characterized by explosive coughing spasms ending in a “whooping” sound Pneumoconiosis (new-moh-koh-nee-OH-sis) General term for lung pathology that occurs after long-term inhalation of pollutants such as coal dust or asbestos, characterized by chronic inflammation, infection, and bronchitis Pneumothorax (new-moh-THOH-raks) Accumulation of air or gas in the pleural space, resulting in collapse of the lung on the affected side Pulmonary edema (PULL-mon-air-ee eh-DEE-mah) Swelling and fluid in the air sacs and bronchioles; often caused by inability of the heart to pump blood; the blood then backs up in the pulmonary blood vessels and fluid seeps into the alveoli and bronchioles Smoker’s respiratory syndrome (SMOH-kers reh-SPY-rah-tor-ee SIN-drohm) A group of respiratory symptoms seen in smokers; includes coughing, wheezing, vocal hoarseness, pharyngitis, dyspnea, and susceptibility to respiratory infections
Respiratory System
Introduction to the Respiratory System
Ventilation
Conducting Passages
Nose and Nasal Cavities
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