© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION CHAPTER 5 Respiratory Function © f9photos/Shutterstock, Inc. © f9photos/Shutterstock, When you see this icon, use the code at the front of the book to access online student resources. LEARNING OBJECTIVES • Discuss normal respiratory anatomy and physiology. • Describe and compare obstructive diseases of the • Describe and compare infectious disorders of the respiratory system. respiratory system. • Describe and compare restrictive diseases of the respiratory system. KEY TERMS active infection cystic fi brosis Legionnaires’ disease residual volume acute bronchitis diaphragm lobar pneumonia secondary TB infection acute lung injury (ALI) drug-induced asthma lung cancer severe acute respiratory acute respiratory distress emphysema Middle East respiratory syndrome (SARS) syndrome (ARDS) epiglottis syndrome sinusitis acute respiratory failure (ARF) epiglottitis minute respiratory volume small-cell carcinoma alveolus exercise-induced asthma mucus spontaneous pneumothorax aspiration pneumonia expiration Mycoplasma pneumoniae status asthmaticus asthma expiratory reserve volume nocturnal asthma surfactant atelectasis extrinsic asthma non-small-cell carcinoma tension pneumothorax bacterial pneumonia forced expiratory volume in nosocomial pneumonia tidal volume blue bloaters 1 second occupational asthma trachea bronchiole forced vital capacity perfusion traumatic pneumothorax bronchiolitis infectious rhinitis pharynx tuberculosis (TB) bronchopneumonia infl uenza pink puffers type a infl uenza bronchus inspiration pleural effusion type B infl uenza chronic bronchitis inspiratory reserve volume pleurisy type C infl uenza chronic obstructive pulmonary interstitial pneumonia Pneumocystis jiroveci ventilation disease (COPD) intrinsic asthma pneumonia ventilation/perfusion ratio cilium laryngitis pneumonia (VQ ratio) community-acquired laryngotracheobronchitis pneumothorax viral pneumonia pneumonia larynx primary TB infection vital capacity 115 9781284042245_CH05.indd 115 2/13/2014 4:32:15 PM © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION 116 CHAPTER 5 Respiratory Function he respiratory system includes the act of breathing. The respiratory tract allows a organs and structures associated with person to breathe in and out approximately Tbreathing and gas exchange. The struc- 23,000 times each day. In fact, if you had a dollar tures of the respiratory system are grouped into for each breath, you would be a millionaire in a two branches—the upper respiratory tract month and a half. The act of breathing allows (mouth, nasal cavity, pharynx, and larynx) for gas exchange of oxygen and carbon dioxide. (FIGURE 5-1) and the lower respiratory tract (tra- Oxygen is necessary for cells to produce energy chea, bronchi, bronchioles, and alveoli). This through cellular metabolism; carbon dioxide is chapter focuses on normal and abnormal states the waste product of this process. Through these of the lungs. The respiratory tract functions functions, the respiratory system plays a pivotal automatically to provide cells with oxygen and role in maintaining homeostasis. to remove carbon dioxide waste. Disorders of The respiratory system consists of two basic the respiratory tract can become serious quickly functional divisions—an air-conducting portion because of the body’s critical need for oxygen. and a gas-exchanging portion (TABLE 5-1). The Patients with these disorders will need astute air-conducting portion delivers air to the lungs, nurses who respond quickly yet thoughtfully. while the gas-exchanging portion allows gas exchange to occur between the air and the blood (Figure 5-1). The gas-exchanging portion Anatomy and Physiology of the respiratory tract includes the lungs with The respiratory system provides vital oxygen their millions of alveoli and capillaries and removes toxic carbon dioxide through the (FIGURE 5-2). Nasal cavity Hard palate Tongue Tonsils Epiglottis Larynx Trachea Esophagus Vocal cords FIGURE 5-1 The upper respiratory tract. Chiras, D. (2011). Human biology (7th ed.). Burlington, MA: Jones & Bartlett Learning. 9781284042245_CH05.indd 116 2/13/2014 4:32:16 PM © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION Anatomy and Physiology 117 TABLE 5-1 Summary of the Respiratory System Organ Function Air Conducting Nasal cavity Filters, warms, and moistens air; also transports air to pharynx Oral cavity Transports air to pharynx; warms and moistens air; helps produce sounds Pharynx Transports air to larynx Epiglottis Covers the opening to the trachea during swallowing Larynx produces sounds; transports air to trachea; helps fi lter incoming air; warms and moistens incoming air Trachea and bronchi Warm and moisten air; transport air to lungs; fi lter incoming air Bronchioles Control air fl ow in the lungs; transport air to alveoli Gas Exchange Alveoli Provide area for exchange of oxygen and carbon dioxide Chiras, D. (2011). Human biology (7th ed.). Burlington, MA: Jones & Bartlett Learning. Nasal Artery Alveolus cavity Bronchiole Mouth Vein (oral cavity) Pharynx Larynx Capillary Trachea network Terminal bronchiole Right Left A bronchus bronchus B Alveoli Capillaries FIGURE 5-2 The respiratory system. (a) This illustration shows the air-conducting portion and the gas-exchange portion of the human respiratory system. The insert shows a higher magnifi cation of the alveoli where oxygen and carbon dioxide exchange occurs. (b) A scanning electron micrograph of the alveoli, showing the rich capillary network surrounding them. © Jones & Bartlett Learning 9781284042245_CH05.indd 117 2/13/2014 4:32:16 PM © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION 118 CHAPTER 5 Respiratory Function Epiglottis Inc. © CMSP/Custom Medical Stock Photo, Thyroid Ventricular fold cartilage (false vocal cord) True vocal cord Tracheal cartilages A BCVocal cords FIGURE 5-3 The vocal cords. (a) Uppermost portion of the respiratory system, showing the location of the vocal cords. (b) Longitudinal section of the larynx showing the location of the vocal cords. Note the presence of the false vocal cord, so named because it does not function in phonation. (c) View into the larynx of a patient showing the true vocal cords from above. Air enters the respiratory system through the nose and mouth, traveling to the pharynx. The pharynx joins the larynx, or voice box (FIGURE 5-3). The larynx is made of cartilage and plays a central role in swallowing and talking. When food is swallowed, the larynx rises so that it is closed by the epiglottis. This process pre- vents food and liquids from entering the lungs, MD/Science Source Martin, © David M. where they would cause severe irritation. Food occasionally enters the lungs, often triggering the cough reflex (a primitive protective reflex). The larynx works much like the strings of a gui- tar or violin to produce sound—tightening and loosening to change pitch. It opens up into the trachea, or windpipe. From the trachea, the air travels to the mainstem bronchi, where it branches into the right and left bronchi, one for each lung (FIGURE 5-4). The left bronchus is nar- FIGURE 5-4 The bifurcation of the trachea at the carina into row and positioned more horizontally than the the right and left mainstem bronchi. right bronchus; the right bronchus is shorter and wider than the left bronchus and extends downward more vertically. Because of the dif- enter the lungs. In times of normal or de- ference in size between the two, objects are creased oxygen needs (e.g., during sleep), the more easily inhaled (aspirated) into the right airways may narrow (constrict) slightly. Dis- bronchus. ease processes may cause constriction to the Inside the lungs, the bronchi branch ex- point of impeding air flow—a dangerous tensively into smaller and smaller tubes, or development. bronchioles, until they reach the alveoli. The air entering the respiratory tract often This branching from larger to smaller mimics contains particles that can be harmful. These the vessels in the cardiovascular system. The particles may include infectious organisms walls of the bronchioles are also like the ves- (e.g., bacteria, viruses, and fungi) and environ- sel walls in that they mostly consist of smooth mental agents (e.g., dust, pollen, and pollut- muscle. The smooth muscle allows for con- ants). The respiratory system is equipped to striction and dilation of the bronchioles to filter out some of these particles as well as to control air flow. When oxygen needs are protect against the body those that gain entry. higher (e.g., during exercise or stress), the air- The air-conducting portion of the respiratory ways open more (dilate) to allow more air to tract filters many particles by trapping them in 9781284042245_CH05.indd 118 2/13/2014 4:32:17 PM © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION Anatomy and Physiology 119 © David M. Phillips/Visuals Unlimited, Inc. Phillips/Visuals Unlimited, © David M. To mouth Cilia Mucous cell B Mucous cell Cilia Dust particle Mucus A To lungs FIGURE 5-5 Mucous trap. (a) Drawing of the lining of the trachea. Mucus produced by the mucous cells of the lining of much of the respiratory system traps bacteria, viruses, and other particulates in the air. The cilia transport the mucus toward the mouth. (b) Higher magnification of the lining showing a mucous cell and ciliated epithelial cells. the mucous layer (FIGURE 5-5). Mucus is a incoming air, humidifying it to prevent drying thick, sticky substance produced by the goblet of