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Chapter 13 The Respiratory System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College © 2015 Pearson Education, Inc. Organs of the Respiratory System Nose Pharynx Larynx Trachea Bronchi Lungs—alveoli © 2015 Pearson Education, Inc. Figure 13.1 The major respiratory organs shown in relation to surrounding structures. Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea Right main (primary) bronchus Left main (primary) bronchus Left lung Right lung Diaphragm © 2015 Pearson Education, Inc. Functions of the Respiratory System Gas exchanges between the blood and external environment Occur in the alveoli of the lungs Passageways to the lungs purify, humidify, and warm the incoming air © 2015 Pearson Education, Inc. The Nose The only externally visible part of the respiratory system Air enters the nose through the external nostrils (nares) Interior of the nose consists of a nasal cavity divided by a nasal septum © 2015 Pearson Education, Inc. Concept Link © 2015 Pearson Education, Inc. Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section. Cribriform plate of ethmoid bone Sphenoidal sinus Posterior nasal aperture Nasopharynx • Pharyngeal tonsil • Opening of pharyngotympanic tube • Uvula Oropharynx • Palatine tonsil • Lingual tonsil Laryngopharynx Esophagus Trachea Frontal sinus Nasal cavity • Nasal conchae (superior, middle and inferior) • Nasal meatuses (superior, middle, and inferior) • Nasal vestibule • Nostril Hard palate Soft palate Tongue Hyoid bone Larynx • Epiglottis • Thyroid cartilage • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract © 2015 Pearson Education, Inc. The Nose Olfactory receptors are located in the mucosa on the superior surface The rest of the cavity is lined with respiratory mucosa, which: Moistens air Traps incoming foreign particles © 2015 Pearson Education, Inc. The Nose Lateral walls have projections called conchae Increase surface area Increase air turbulence within the nasal cavity The nasal cavity is separated from the oral cavity by the palate Anterior hard palate (bone) Posterior soft palate (unsupported) © 2015 Pearson Education, Inc. Paranasal Sinuses Cavities within bones surrounding the nasal cavity are called sinuses Sinuses are located in the following bones: Frontal Sphenoid Ethmoid Maxillary © 2015 Pearson Education, Inc. Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section. Cribriform plate of ethmoid bone Sphenoidal sinus Posterior nasal aperture Nasopharynx • Pharyngeal tonsil • Opening of pharyngotympanic tube • Uvula Oropharynx • Palatine tonsil • Lingual tonsil Laryngopharynx Esophagus Trachea Frontal sinus Nasal cavity • Nasal conchae (superior, middle and inferior) • Nasal meatuses (superior, middle, and inferior) • Nasal vestibule • Nostril Hard palate Soft palate Tongue Hyoid bone Larynx • Epiglottis • Thyroid cartilage • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract © 2015 Pearson Education, Inc. Paranasal Sinuses Functions of the sinuses: Lighten the skull Act as resonance chambers for speech Produce mucus that drains into the nasal cavity © 2015 Pearson Education, Inc. Pharynx (Throat) Muscular passage from nasal cavity to larynx Three regions of the pharynx: 1. Nasopharynx—superior region behind nasal cavity 2. Oropharynx—middle region behind mouth 3. Laryngopharynx—inferior region attached to larynx The oropharynx and laryngopharynx are common passageways for air and food © 2015 Pearson Education, Inc. Figure 13.2a Basic anatomy of the upper respiratory tract, sagittal section. Pharynx • Nasopharynx • Oropharynx • Laryngopharynx (a) Regions of the pharynx © 2015 Pearson Education, Inc. Pharynx (Throat) Pharyngotympanic tubes open into the nasopharynx Tonsils of the pharynx Pharyngeal tonsil (adenoid) is located in the nasopharynx Palatine tonsils are located in the oropharynx Lingual tonsils are found at the base of the tongue © 2015 Pearson Education, Inc. Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section. Cribriform plate of ethmoid bone Sphenoidal sinus Posterior nasal aperture Nasopharynx • Pharyngeal tonsil • Opening of pharyngotympanic tube • Uvula Oropharynx • Palatine tonsil • Lingual tonsil Laryngopharynx Esophagus Trachea Frontal sinus Nasal cavity • Nasal conchae (superior, middle and inferior) • Nasal meatuses (superior, middle, and inferior) • Nasal vestibule • Nostril Hard palate Soft palate Tongue Hyoid bone Larynx • Epiglottis • Thyroid cartilage • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract © 2015 Pearson Education, Inc. Larynx (Voice Box) Routes air and food into proper channels Plays a role in speech Made of eight rigid hyaline cartilages and a spoonshaped flap of elastic cartilage (epiglottis) © 2015 Pearson Education, Inc. Larynx (Voice Box) Thyroid cartilage Largest of the hyaline cartilages Protrudes anteriorly (Adam’s apple) Epiglottis Protects the superior opening of the larynx Routes food to the posteriorly situated esophagus and routes air toward the trachea When swallowing, the epiglottis rises and forms a lid over the opening of the larynx © 2015 Pearson Education, Inc. Larynx (Voice Box) Vocal folds (true vocal cords) Vibrate with expelled air The glottis consists of the vocal cords and the slitlike pathway (opening) © 2015 Pearson Education, Inc. Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section. Cribriform plate of ethmoid bone Sphenoidal sinus Posterior nasal aperture Nasopharynx • Pharyngeal tonsil • Opening of pharyngotympanic tube • Uvula Oropharynx • Palatine tonsil • Lingual tonsil Laryngopharynx Esophagus Trachea Frontal sinus Nasal cavity • Nasal conchae (superior, middle and inferior) • Nasal meatuses (superior, middle, and inferior) • Nasal vestibule • Nostril Hard palate Soft palate Tongue Hyoid bone Larynx • Epiglottis • Thyroid cartilage • Vocal fold • Cricoid cartilage (b) Detailed anatomy of the upper respiratory tract © 2015 Pearson Education, Inc. Trachea (Windpipe) 4-inch-long tube that connects larynx with bronchi Walls are reinforced with C-shaped hyaline cartilage, which keeps the trachea patent Lined with ciliated mucosa Cilia beat continuously in the opposite direction of incoming air Expel mucus loaded with dust and other debris away from lungs © 2015 Pearson Education, Inc. Figure 13.3a Structural relationship of the trachea and esophagus. Posterior Mucosa Submucosa Esophagus Trachealis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia (a) © 2015 Pearson Education, Inc. Anterior Figure 13.3b Structural relationship of the trachea and esophagus. (b) © 2015 Pearson Education, Inc. Main (Primary) Bronchi Formed by division of the trachea Each bronchus enters the lung at the hilum (medial depression) Right bronchus is wider, shorter, and straighter than left Bronchi subdivide into smaller and smaller branches © 2015 Pearson Education, Inc. Figure 13.1 The major respiratory organs shown in relation to surrounding structures. Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea Right main (primary) bronchus Left main (primary) bronchus Left lung Right lung Diaphragm © 2015 Pearson Education, Inc. Lungs Occupy most of the thoracic cavity Heart occupies central portion called mediastinum Apex is near the clavicle (superior portion) Base rests on the diaphragm (inferior portion) Each lung is divided into lobes by fissures Left lung—two lobes Right lung—three lobes © 2015 Pearson Education, Inc. Coverings of the Lungs Serosa covers the outer surface of the lungs Pulmonary (visceral) pleura covers the lung surface Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers to allow gliding and decrease friction during breathing Pleural space (between the layers) is more of a potential space © 2015 Pearson Education, Inc. Figure 13.4a Anatomical relationships of organs in the thoracic cavity. Intercostal muscle Rib Trachea Parietal pleura Pleural cavity Visceral pleura Lung Thymus Apex of lung Right superior lobe Horizontal fissure Right middle lobe Oblique fissure Right inferior lobe Heart (in pericardial cavity of mediastinum) Diaphragm Base of lung Left superior lobe Oblique fissure Left inferior lobe (a) Anterior view. The lungs flank mediastinal structures laterally. © 2015 Pearson Education, Inc. Figure 13.4b Anatomical relationships of organs in the thoracic cavity. Vertebra Posterior Esophagus (in posterior mediastinum) Root of lung at hilum • Left main bronchus • Left pulmonary artery • Left pulmonary vein Right lung Parietal pleura Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Sternum Heart (in mediastinum) Anterior mediastinum Anterior (b) Transverse section through the thorax, viewed from above. © 2015 Pearson Education, Inc. Bronchial (Respiratory) Tree Divisions All but the smallest of these passageways have reinforcing cartilage in their walls Conduits to and from the respiratory zone Primary bronchi Secondary bronchi Tertiary bronchi Bronchioles Terminal bronchioles © 2015 Pearson Education, Inc. Respiratory Zone Structures Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli (air sacs) © 2015 Pearson Education, Inc. Figure 13.5a Respiratory zone structures. Alveolar duct Respiratory bronchioles Terminal bronchiole (a) Diagrammatic view of respiratory bronchioles, alveolar ducts, and alveoli © 2015 Pearson Education, Inc. Alveoli Alveolar duct Alveolar sac Figure 13.5b Respiratory zone structures. Alveolar duct Alveolus (b) Light micrograph of human lung tissue, showing the final divisions of the respiratory tree (120×) © 2015 Pearson Education, Inc. Alveolar pores The Respiratory Membrane Thin squamous epithelial layer lines alveolar walls Alveolar pores connect neighboring air sacs Pulmonary capillaries cover external surfaces of alveoli Respiratory membrane (air-blood barrier) On one side of the membrane is air, and on the other side is blood flowing past Formed by alveolar and capillary walls © 2015 Pearson Education, Inc. The Respiratory Membrane Gas crosses the respiratory membrane by diffusion Oxygen enters the blood Carbon dioxide enters the alveoli Alveolar macrophages (“dust cells”) add protection by picking up bacteria, carbon particles, and other debris Surfactant (a lipid molecule) coats gas-exposed alveolar surfaces © 2015 Pearson Education, Inc. Figure 13.6 Anatomy of the respiratory membrane (air-blood barrier). Red blood cell Capillary Endothelial cell nucleus Alveolar pores Capillary O2 CO2 Macrophage Nucleus of squamous epithelial cell Respiratory membrane Alveolus Alveolar epithelium Fused basement membranes Capillary endothelium Alveoli (gasfilled air spaces) Squamous Red blood Surfactantcell in secreting cell epithelial cell of alveolar wall capillary © 2015 Pearson Education, Inc. Four Events of Respiration 1. Pulmonary ventilation—moving air into and out of the lungs (commonly called breathing) 2. External respiration—gas exchange between pulmonary blood and alveoli Oxygen is loaded into the blood Carbon dioxide is unloaded from the blood © 2015 Pearson Education, Inc. Four Events of Respiration 3. Respiratory gas transport—transport of oxygen and carbon dioxide via the bloodstream 4. Internal respiration—gas exchange between blood and tissue cells in systemic capillaries © 2015 Pearson Education, Inc. Mechanics of Breathing (Pulmonary Ventilation) Completely mechanical process that depends on volume changes in the thoracic cavity Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure © 2015 Pearson Education, Inc. Mechanics of Breathing (Pulmonary Ventilation) Two phases Inspiration = inhalation Flow of air into lungs Expiration = exhalation Air leaving lungs © 2015 Pearson Education, Inc. Mechanics of Breathing (Pulmonary Ventilation) Inspiration Diaphragm and external intercostal muscles contract The size of the thoracic cavity increases External air is pulled into the lungs as a result of: Increase in intrapulmonary volume Decrease in gas pressure Air is sucked into the lungs © 2015 Pearson Education, Inc. Figure 13.7a Rib cage and diaphragm positions during breathing. Changes in anterior-posterior and superior-inferior dimensions Ribs elevated as external intercostals contract External intercostal muscles Changes in lateral dimensions Full inspiration (External intercostals contract) Diaphragm moves inferiorly during contraction (a) Inspiration: Air (gases) flows into the lungs © 2015 Pearson Education, Inc. Pressure relative to atmospheric pressure Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration. +2 +1 Inspiration Expiration Intrapulmonary pressure 0 −1 −2 (a) Volume of breath Volume (L) 0.5 0 −0.5 (b) © 2015 Pearson Education, Inc. Mechanics of Breathing (Pulmonary Ventilation) Expiration Largely a passive process that depends on natural lung elasticity As muscles relax, air is pushed out of the lungs as a result of: Decrease in intrapulmonary volume Increase in gas pressure Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage © 2015 Pearson Education, Inc. Mechanics of Breathing (Pulmonary Ventilation) Normal pressure within the pleural space is always negative (intrapleural pressure) Differences in lung and pleural space pressures keep lungs from collapsing Atelectasis is collapsed lung Pneumothorax is the presence of air in the intrapleural space © 2015 Pearson Education, Inc. Figure 13.7b Rib cage and diaphragm positions during breathing. Changes in anterior-posterior and superior-inferior dimensions Changes in lateral dimensions Ribs depressed as external intercostals relax External intercostal muscles Diaphragm moves superiorly as it relaxes (b) Expiration: Air (gases) flows out of the lungs © 2015 Pearson Education, Inc. Expiration (External intercostals relax) Pressure relative to atmospheric pressure Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration. +2 +1 Inspiration Expiration Intrapulmonary pressure 0 −1 −2 (a) Volume of breath Volume (L) 0.5 0 −0.5 (b) © 2015 Pearson Education, Inc. Respiratory Volumes and Capacities Normal breathing moves about 500 ml of air with each breath This respiratory volume is tidal volume (TV) Many factors affect respiratory capacity A person’s size Sex Age Physical condition © 2015 Pearson Education, Inc. Respiratory Volumes and Capacities Inspiratory reserve volume (IRV) Amount of air that can be taken in forcibly over the tidal volume Usually around 3,100 ml Expiratory reserve volume (ERV) Amount of air that can be forcibly exhaled after a tidal expiration Approximately 1,200 ml © 2015 Pearson Education, Inc. Respiratory Volumes and Capacities Residual volume Air remaining in lung after expiration Allows gas exchange to go on continuously, even between breaths, and helps keep alveoli open (inflated) About 1,200 ml © 2015 Pearson Education, Inc. Respiratory Volumes and Capacities Vital capacity The total amount of exchangeable air Vital capacity = TV + IRV + ERV 4,800 ml in men; 3,100 ml in women Dead space volume Air that remains in conducting zone and never reaches alveoli About 150 ml © 2015 Pearson Education, Inc. Respiratory Volumes and Capacities Functional volume Air that actually reaches the respiratory zone Usually about 350 ml Respiratory capacities are measured with a spirometer © 2015 Pearson Education, Inc. Figure 13.9 Idealized tracing of the various respiratory volumes of a healthy young adult male. 6,000 Milliliters (ml) 5,000 4,000 Inspiratory reserve volume 3,100 ml 3,000 2,000 1,000 0 © 2015 Pearson Education, Inc. Tidal volume 500 ml Expiratory reserve volume 1,200 ml Residual volume 1,200 ml Vital capacity 4,800 ml Total lung capacity 6,000 ml Nonrespiratory Air (Gas) Movements Can be caused by reflexes or voluntary actions Examples: Cough and sneeze—clears lungs of debris Crying—emotionally induced mechanism Laughing—similar to crying Hiccup—sudden inspirations Yawn—very deep inspiration © 2015 Pearson Education, Inc. Table 13.1 Nonrespiratory Air (Gas) Movements © 2015 Pearson Education, Inc. Respiratory Sounds Sounds are monitored with a stethoscope Two recognizable sounds can be heard with a stethoscope: 1. Bronchial sounds—produced by air rushing through large passageways such as the trachea and bronchi 2. Vesicular breathing sounds—soft sounds of air filling alveoli © 2015 Pearson Education, Inc. External Respiration, Gas Transport, and Internal Respiration Gas exchanges occur as a result of diffusion Movement of the gas is toward the area of lower concentration © 2015 Pearson Education, Inc. Figure 13.10 Gas exchanges in the body occur according to the laws of diffusion. Inspired air: Alveoli of lungs: CO2 O2 O2 CO2 O2 CO2 External respiration Pulmonary arteries Alveolar capillaries Blood leaving tissues and entering lungs: Pulmonary veins Blood leaving lungs and entering tissue capillaries: Heart O2 CO2 Tissue capillaries Systemic veins Internal respiration Systemic arteries CO2 O2 Tissue cells: O2 CO2 © 2015 Pearson Education, Inc. O2 CO2 External Respiration Oxygen is loaded into the blood The alveoli always have more oxygen than the blood Oxygen moves by diffusion towards the area of lower concentration Pulmonary capillary blood gains oxygen © 2015 Pearson Education, Inc. External Respiration Carbon dioxide is unloaded out of the blood Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli Pulmonary capillary blood gives up carbon dioxide to be exhaled Blood leaving the lungs is oxygen rich and carbon dioxide poor © 2015 Pearson Education, Inc. Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body. (a) External respiration in the lungs (pulmonary gas exchange) Oxygen is loaded into the blood and carbon dioxide is unloaded. Alveoli (air sacs) O2 Loading of O2 Hb + O2 HbO2 (Oxyhemoglobin is formed) CO2 Unloading of CO2 HCO3−+ H+ H2CO3 CO2+ H2O BicarCarbonic Water bonate acid ion Plasma Red blood cell Pulmonary capillary © 2015 Pearson Education, Inc. Gas Transport in the Blood Oxygen transport in the blood Most oxygen travels attached to hemoglobin and forms oxyhemoglobin (HbO2) A small dissolved amount is carried in the plasma © 2015 Pearson Education, Inc. Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body. (a) External respiration in the lungs (pulmonary gas exchange) Oxygen is loaded into the blood and carbon dioxide is unloaded. Alveoli (air sacs) O2 Loading of O2 Hb + O2 HbO2 (Oxyhemoglobin is formed) CO2 Unloading of CO2 HCO3−+ H+ H2CO3 CO2+ H2O BicarCarbonic Water bonate acid ion Plasma Red blood cell Pulmonary capillary © 2015 Pearson Education, Inc. Gas Transport in the Blood Carbon dioxide transport in the blood Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO3–) A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen © 2015 Pearson Education, Inc. Concept Link © 2015 Pearson Education, Inc. Gas Transport in the Blood For carbon dioxide to diffuse out of blood into the alveoli, it must be released from its bicarbonate form: Bicarbonate ions enter RBC Combine with hydrogen ions Form carbonic acid (H2CO3) Carbonic acid splits to form water + CO2 Carbon dioxide diffuses from blood into alveoli © 2015 Pearson Education, Inc. Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body. (a) External respiration in the lungs (pulmonary gas exchange) Oxygen is loaded into the blood and carbon dioxide is unloaded. Alveoli (air sacs) O2 Loading of O2 Hb + O2 HbO2 (Oxyhemoglobin is formed) CO2 Unloading of CO2 HCO3−+ H+ H2CO3 CO2+ H2O BicarCarbonic Water bonate acid ion Plasma Red blood cell Pulmonary capillary © 2015 Pearson Education, Inc. Internal Respiration Exchange of gases between blood and body cells An opposite reaction to what occurs in the lungs Carbon dioxide diffuses out of tissue to blood (called loading) Oxygen diffuses from blood into tissue (called unloading) © 2015 Pearson Education, Inc. Figure 13.11b Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body. (b) Internal respiration in the body tissues (systemic capillary gas exchange) Oxygen is unloaded and carbon dioxide is loaded into the blood. Tissue cells CO2 Loading of CO2 CO2 +H2O H2CO3 Water Carbonic acid Plasma O2 Unloading of O2 H++ HCO3− Bicarbonate ion HbO2 Hb + O2 Systemic capillary Red blood cell © 2015 Pearson Education, Inc. Neural Regulation of Respiration Activity of respiratory muscles is transmitted to and from the brain by phrenic and intercostal nerves Neural centers that control rate and depth are located in the medulla and pons Medulla—sets basic rhythm of breathing and contains a pacemaker (self-exciting inspiratory center) called the ventral respiratory group (VRG) Pons—appears to smooth out respiratory rate © 2015 Pearson Education, Inc. Neural Regulation of Respiration Normal respiratory rate (eupnea) 12 to 15 respirations per minute Hyperpnea Increased respiratory rate, often due to extra oxygen needs © 2015 Pearson Education, Inc. Figure 13.12 Breathing control centers, sensory inputs, and effector nerves. Breathing control centers: • Pons centers • Medulla centers Efferent nerve impulses from medulla trigger contraction of inspiratory muscles. • Phrenic nerves • Intercostal nerves Afferent impulses to medulla Breathing control centers stimulated by: CO2 increase in blood (acts directly on medulla centers by causing a drop in pH of CSF) CSF in brain sinus © 2015 Pearson Education, Inc. Nerve impulse from O2 sensor indicating O2 decrease Intercostal muscles Diaphragm O2 sensor in aortic body of aortic arch Non-Neural Factors Influencing Respiratory Rate and Depth Physical factors Increased body temperature Exercise Talking Coughing Volition (conscious control) Emotional factors such as fear, anger, and excitement © 2015 Pearson Education, Inc. Non-Neural Factors Influencing Respiratory Rate and Depth Chemical factors: CO2 levels The body’s need to rid itself of CO2 is the most important stimulus for breathing Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood increase the rate and depth of breathing Changes in carbon dioxide act directly on the medulla oblongata © 2015 Pearson Education, Inc. Non-Neural Factors Influencing Respiratory Rate and Depth Chemical factors: oxygen levels Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and common carotid artery Information is sent to the medulla Oxygen is the stimulus for those whose systems have become accustomed to high levels of carbon dioxide as a result of disease © 2015 Pearson Education, Inc. Non-Neural Factors Influencing Respiratory Rate and Depth Chemical factors Hyperventilation Rising levels of CO2 in the blood (acidosis) result in faster, deeper breathing Blows off more CO2 to restore normal blood pH May result in apnea and dizziness and lead to alkalosis © 2015 Pearson Education, Inc. Non-Neural Factors Influencing Respiratory Rate and Depth Chemical factors Hypoventilation Results when blood becomes alkaline (alkalosis) Extremely slow or shallow breathing Allows CO2 to accumulate in the blood © 2015 Pearson Education, Inc. Respiratory Disorders: Chronic Obstructive Pulmonary Disease (COPD) Exemplified by chronic bronchitis and emphysema Major causes of death and disability in the United States © 2015 Pearson Education, Inc. Respiratory Disorders: Chronic Obstructive Pulmonary Disease (COPD) Features of these diseases 1. Patients almost always have a history of smoking 2. Labored breathing (dyspnea) becomes progressively more severe 3. Coughing and frequent pulmonary infections are common © 2015 Pearson Education, Inc. Respiratory Disorders: Chronic Obstructive Pulmonary Disease (COPD) Features of these diseases (continued) 4. Most victims are hypoxic, retain carbon dioxide, and have respiratory acidosis Those who acquire infections will ultimately develop respiratory failure © 2015 Pearson Education, Inc. Respiratory Disorders: Chronic Bronchitis Mucosa of the lower respiratory passages becomes severely inflamed Excessive mucus production impairs ventilation and gas exchange Patients become cyanotic and are sometimes called “blue bloaters” as a result of chronic hypoxia © 2015 Pearson Education, Inc. Respiratory Disorders: Emphysema Alveoli permanently enlarge as adjacent chambers break through and are destroyed Chronic inflammation promotes lung fibrosis, and lungs lose elasticity Patients use a large amount of energy to exhale as exhalation becomes an active process Overinflation of the lungs leads to a permanently expanded barrel chest Cyanosis appears late in the disease; sufferers are often called “pink puffers” © 2015 Pearson Education, Inc. Figure 13.13 The pathogenesis of COPD. • Tobacco smoke • Air pollution Continual bronchial irritation and inflammation Breakdown of elastin in connective tissue of lungs Chronic bronchitis • Excessive mucus produced, • Chronic productive cough Emphysema • Destruction of alveolar walls • Loss of lung elasticity • Airway obstruction or air trapping • Dyspnea • Frequent infections Respiratory failure © 2015 Pearson Education, Inc. Lung Cancer Extremely aggressive and metastasizes rapidly Accounts for one-third of all U.S. cancer deaths Increased incidence is associated with smoking Three common types: 1. Squamous cell carcinoma 2. Adenocarcinoma 3. Small cell carcinoma © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Premature infants have problems keeping their lungs inflated because of a lack of surfactant in their alveoli. (Surfactant is formed late in pregnancy around 28 to 30 weeks of pregnancy) Infant respiratory distress syndrome (IRDS)— surfactant production is inadequate © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Significant birth defects affecting the respiratory system: Cleft palate Cystic fibrosis—oversecretion of thick mucus clogs the respiratory system © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Respiratory rate changes throughout life Newborns: 40 to 80 respirations per minute Infants: 30 respirations per minute Age 5: 25 respirations per minute Adults: 12 to 18 respirations per minute Rate often increases somewhat with old age © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Sudden infant death syndrome (SIDS) Apparently healthy infant stops breathing and dies during sleep Some cases are thought to be a problem of the neural respiratory control center One-third of cases appear to be due to heart rhythm abnormalities Recent research shows a genetic component © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Asthma Chronically inflamed hypersensitive bronchiole passages Respond to irritants with dyspnea, coughing, and wheezing © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System During youth and middle age, most respiratory system problems are a result of external factors, such as infections and substances that physically block respiratory passageways © 2015 Pearson Education, Inc. Developmental Aspects of the Respiratory System Aging effects Elasticity of lungs decreases Vital capacity decreases Blood oxygen levels decrease Stimulating effects of carbon dioxide decrease Elderly are often hypoxic and exhibit sleep apnea More risks of respiratory tract infection © 2015 Pearson Education, Inc.