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Chapter 22A Respiratory System: Slides by Barbara Heard and W. Rose.
HESC310 4/12/2017 Chapter 22A Respiratory System: Slides by Barbara Heard and W. Rose. figures from Marieb & Hoehn 9th ed. Portions copyright Pearson Education Axial Skeleton
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Respiratory System Functions
Respiration Supply O2, dispose of CO2 Four processes (next slide) Involves circulatory system Olfaction Speech
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Processes of Respiration
Pulmonary ventilation (breathing): moving air into and out of lungs External respiration: O2 and CO2 exchange between lungs and blood Transport: O2 and CO2 in blood Internal respiration: O2 and CO2 exchange between systemic blood vessels and tissues Respiratory system Circulatory system © 2013 Pearson Education, Inc.
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Respiratory System: Functional Anatomy
Major organs Nose, nasal cavity, and paranasal sinuses Pharynx Larynx Trachea Bronchi and their branches Lungs and alveoli © 2013 Pearson Education, Inc.
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Figure 22.1 Major respiratory organs and surrounding structures
Nasal cavity Oral cavity Nostril Pharynx Larynx Trachea Carina of trachea Left main (primary) bronchus Right main (primary) bronchus Left lung Right lung Diaphragm © 2013 Pearson Education, Inc.
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Respiratory zone-site of gas exchange
Functional Anatomy Respiratory zone-site of gas exchange Microscopic structures-respiratory bronchioles, alveolar ducts, and alveoli Conducting zone-conduits to gas exchange sites Includes all other respiratory structures; cleanses, warms, humidifies air Diaphragm and other respiratory muscles promote ventilation PLAY Animation: Rotating face © 2013 Pearson Education, Inc.
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Nose Provides an airway for respiration
Moistens and warms entering air Filters and cleans inspired air Serves as resonating chamber for speech Houses olfactory receptors © 2013 Pearson Education, Inc.
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Figure 22.2b The external nose.
Frontal bone Nasal bone Septal cartilage Maxillary bone (frontal process) Nasal cartilages Dense fibrous connective tissue Nares (nostrils) External skeletal framework © 2013 Pearson Education, Inc.
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Nasal cavity Divided by midline nasal septum
Opens into nasopharynx posteriorly Roof: ethmoid and sphenoid bones Lateral walls: ethmoid, inferior conchae, palatine bones Floor: hard palate (maxilla & palatine bones), soft palate (muscle) Lined with mucous membranes Olfactory mucosa Respiratory mucosa: ciliated; cilia sweep mucus toward pharynx © 2013 Pearson Education, Inc.
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Nasal cavity: left lateral wall Nasal septum removed.
Frontal sinus Superior, middle, and inferior meatus Superior nasal concha Ethmoid bone Middle nasal concha Sphenoid sinus Nasal bone Inferior nasal concha Maxillary bone Palatine bone Nasal cavity: left lateral wall Nasal septum removed.
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Nasal cavity: midline structures
Frontal sinus Nasal bone Perpendicular plate of ethmoid bone Sphenoid sinus Septal cartilage Vomer Palatine bone Hard palate Maxilla Nasal cavity: midline structures Septum in place. Note ethmoid bone, vomer, septal cartilage.
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Figure 22.3b The upper respiratory tract.
Cribriform plate of ethmoid bone Frontal sinus Sphenoid sinus Nasal cavity Posterior nasal aperture Nasal conchae (superior, middle and inferior) Nasopharynx Pharyngeal tonsil Nasal meatuses (superior, middle, and inferior) Opening of pharyngotympanic tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Vestibular fold Thyroid cartilage Esophagus Vocal fold Cricoid cartilage Trachea Thyroid gland Illustration © 2013 Pearson Education, Inc.
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Figure 22.3a The upper respiratory tract.
Olfactory nerves Olfactory epithelium Superior nasal concha and superior nasal meatus Mucosa of pharynx Middle nasal concha and middle nasal meatus Tubal tonsil Inferior nasal concha and inferior nasal meatus Pharyngotympanic (auditory) tube Hard palate Nasopharynx Soft palate Uvula Photograph © 2013 Pearson Education, Inc.
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Nasal conchae-superior, middle, and inferior
Nasal Cavity Nasal conchae-superior, middle, and inferior Protrude medially from lateral walls Increase mucosal area Enhance air turbulence Nasal meatus Groove inferior to each concha © 2013 Pearson Education, Inc.
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Functions of the Nasal Mucosa and Conchae
During inhalation: filter, heat, moisten air During exhalation: reclaim heat, moisture © 2013 Pearson Education, Inc.
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In frontal, sphenoid, ethmoid, and maxillary bones
Paranasal Sinuses In frontal, sphenoid, ethmoid, and maxillary bones Lighten skull; secrete mucus; help to warm and moisten air © 2013 Pearson Education, Inc.
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Homeostatic Imbalance
Rhinitis Inflammation of nasal mucosa Nasal mucosa continuous with mucosa of respiratory tract spreads from nose throat chest Spreads to tear ducts and paranasal sinuses causing Blocked sinus passageways air absorbed vacuum sinus headache © 2013 Pearson Education, Inc.
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Upper respiratory tract
Pharynx Nasopharynx Oropharynx Laryngopharynx Regions of the pharynx © 2013 Pearson Education, Inc.
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Air passageway posterior to nasal cavity
Nasopharynx Air passageway posterior to nasal cavity Lining - pseudostratified columnar epithelium Soft palate and uvula close nasopharynx during swallowing Pharyngeal tonsil (adenoids) on posterior wall Pharyngotympanic (auditory) tubes drain and equalize pressure in middle ear; open into lateral walls © 2013 Pearson Education, Inc.
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Passageway for food and air from level of soft palate to epiglottis
Oropharynx Passageway for food and air from level of soft palate to epiglottis Lining of stratified squamous epithelium Palatine tonsils-in lateral walls of fauces Lingual tonsil-on posterior surface of tongue © 2013 Pearson Education, Inc.
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Passageway for food and air Posterior to upright epiglottis
Laryngopharynx Passageway for food and air Posterior to upright epiglottis Extends to larynx, where continuous with esophagus Lined with stratified squamous epithelium © 2013 Pearson Education, Inc.
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Figure 22.3b The upper respiratory tract.
Cribriform plate of ethmoid bone Frontal sinus Sphenoid sinus Nasal cavity Posterior nasal aperture Nasal conchae (superior, middle and inferior) Nasopharynx Pharyngeal tonsil Nasal meatuses (superior, middle, and inferior) Opening of pharyngotympanic tube Nasal vestibule Uvula Nostril Oropharynx Hard palate Palatine tonsil Soft palate Isthmus of the fauces Tongue Lingual tonsil Laryngopharynx Hyoid bone Larynx Epiglottis Vestibular fold Thyroid cartilage Esophagus Vocal fold Cricoid cartilage Trachea Thyroid gland Illustration © 2013 Pearson Education, Inc.
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Provides patent airway Routes air and food into proper channels
Larynx Structures through which air passes, between laryngopharynx and trachea Provides patent airway Routes air and food into proper channels Voice production © 2013 Pearson Education, Inc.
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Larynx Thyroid cartilage (laryngeal prominence = Adam's apple)
Cricoid cartilage ring-shaped Other cartilages Epiglottis (elastic cartilage); covers laryngeal inlet during swallowing to prevent food/water from entering larynx © 2013 Pearson Education, Inc.
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Larynx Epiglottis Hyoid bone Thyroid cartilage Laryngeal prominence
(Adam’s apple) Cricoid cartilage Tracheal cartilages Anterior superficial view
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Larynx Hyoid bone Epiglottis Vestibular fold (false vocal cord)
Thyroid cartilage Vocal fold (true vocal cord) Cricoid cartilage Tracheal cartilages Sagittal view; anterior surface to the right © 2013 Pearson Education, Inc.
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Vestibular folds (false vocal cords)
Larynx Vocal ligaments Contain elastic fibers Form core of vocal folds (true vocal cords) Glottis-opening between vocal folds Folds vibrate to produce sound as air rushes up from lungs Vestibular folds (false vocal cords) Superior to vocal folds No part in sound production Help to close glottis during swallowing © 2013 Pearson Education, Inc.
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Figure 22.5. Vocal fold movements.
Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Lumen of trachea Vocal folds in closed position; closed glottis Vocal folds in open position; open glottis © 2013 Pearson Education, Inc.
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Voice Production Intermittent release of expired air while opening and closing glottis Pitch determined by length and tension of vocal cords Loudness depends upon force of air Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality Sound is "shaped" into language by muscles of pharynx, tongue, soft palate, lips © 2013 Pearson Education, Inc.
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Vocal folds can act as sphincter to prevent air passage
Larynx Vocal folds can act as sphincter to prevent air passage Example: Valsalva's maneuver Glottis closes to prevent exhalation Abdominal muscles contract Intra-abdominal pressure rises Helps to stabilizes trunk during heavy lifting; helps to empty bladder or bowel © 2013 Pearson Education, Inc.
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Air passageway from larynx into mediastinum; “windpipe”
Trachea Air passageway from larynx into mediastinum; “windpipe” Wall composed of three layers Mucosa-ciliated pseudostratified epithelium with goblet cells Submucosa Adventitia-outermost layer made of connective tissue; encases C-shaped rings of hyaline cartilage Carina where trachea branches into two main bronchi © 2013 Pearson Education, Inc.
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Trachea Cross section of trachea and esophagus Posterior Mucosa
Submucosa Trachealis muscle Lumen of trachea Seromucous gland in submucosa Hyaline cartilage Adventitia Anterior Cross section of trachea and esophagus © 2013 Pearson Education, Inc.
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Bronchi and Subdivisions
Bronchial (respiratory) tree: Air passages undergo ~23 orders of branching Conducting zone Respiratory zone © 2013 Pearson Education, Inc.
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Conducting Zone Structures
Trachea Right and left main bronchi Each main bronchus enters hilum of one lung Right main bronchus wider, shorter, more vertical than left Lobar bronchi One to each lobe of each lung: 3 right, 2 left Segmental bronchi Smaller and smaller branches Bronchioles < 1 mm in diameter Terminal bronchioles < 0.5 mm diameter © 2013 Pearson Education, Inc.
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Figure 22.7 Conducting zone passages.
Trachea Superior lobe of left lung Left main (primary) bronchus Superior lobe of right lung Lobar (secondary) bronchus Segmental (tertiary) bronchus Middle lobe of right lung Inferior lobe of right lung Inferior lobe of left lung © 2013 Pearson Education, Inc.
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Conducting Zone Structures
From bronchi through bronchioles, structural changes occur Cartilage rings gradually disappear Elastic fibers replace cartilage in bronchioles Epithelium changes from pseudostratified columnar to cuboidal Cilia, goblet cells become sparse Relative amount of smooth muscle increases Allows constriction © 2013 Pearson Education, Inc.
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Where gas exchange takes place Begins at ends of terminal bronchioles
Respiratory Zone Where gas exchange takes place Begins at ends of terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sacs Alveolar sacs contain clusters of alveoli ~300 million alveoli make up most of lung volume Sites of gas exchange © 2013 Pearson Education, Inc.
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Figure 22.8a Respiratory zone structures.
Alveoli Alveolar duct Respiratory bronchioles Alveolar duct Terminal bronchiole Alveolar sac © 2013 Pearson Education, Inc.
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Figure 22.8b Respiratory zone structures.
bronchiole Alveolar duct Alveolar pores Alveoli Alveolar sac © 2013 Pearson Education, Inc.
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Alveolar and capillary walls and their fused basement membranes
Respiratory Membrane Alveolar and capillary walls and their fused basement membranes ~0.5-µm-thick; gas exchange across membrane by simple diffusion Alveolar walls Single layer of squamous epithelium (type I alveolar cells) Scattered cuboidal type II alveolar cells secrete surfactant and antimicrobial proteins © 2013 Pearson Education, Inc.
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Figure 22.9a Alveoli and the respiratory membrane.
Terminal bronchiole Respiratory bronchiole Smooth muscle Elastic fibers Alveolus Capillaries Diagrammatic view of capillary-alveoli relationships © 2013 Pearson Education, Inc.
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Surrounded by fine elastic fibers and pulmonary capillaries
Alveoli Surrounded by fine elastic fibers and pulmonary capillaries Alveolar pores connect adjacent alveoli Equalize air pressure throughout lung Alveolar macrophages keep alveolar surfaces “clean” 2 million dead macrophages/hour carried by cilia throat swallowed © 2013 Pearson Education, Inc.
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Figure 22.9c Alveoli and the respiratory membrane.
Red blood cell Nucleus of type I alveolar cell Alveolar pores Capillary Capillary Macrophage Alveolus Endothelial cell nucleus Alveolus Alveolar epithelium Respiratory membrane Fused basement membranes of alveolar epithelium and capillary endothelium Alveoli (gas-filled air spaces) Red blood cell in capillary Type II alveolar cell Type I alveolar cell Capillary endothelium Detailed anatomy of the respiratory membrane © 2013 Pearson Education, Inc.
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Composed primarily of alveoli Elastic connective tissue
Lungs Composed primarily of alveoli Elastic connective tissue Apex (superior), base (rests on diaphragm) Root (hilum): site of entry/exit of blood vessels, bronchi, lymphatics, nerves Left lung smaller than right Cardiac notch-concavity for heart Superior, inferior lobes Right lung Superior, middle, inferior lobes © 2013 Pearson Education, Inc.
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Figure 22.10c Anatomical relationships of organs in the thoracic cavity.
Esophagus (in mediastinum) Posterior Vertebra Root of lung at hilum • Left main bronchus Right lung • Left pulmonary artery Parietal pleura • Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. © 2013 Pearson Education, Inc.
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Figure 22.10a. Organs in the thoracic cavity.
Intercostal muscle Rib Parietal pleura Lung Pleural cavity Visceral pleura Trachea Thymus Apex of lung Left superior lobe Right superior lobe Oblique fissure Horizontal fissure Right middle lobe Left inferior lobe Oblique fissure Right inferior lobe Heart (in mediastinum) Diaphragm Cardiac notch Base of lung Anterior view. The lungs flank mediastinal structures laterally. © 2013 Pearson Education, Inc.
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Photograph of medial view of the left lung.
Figure 22.10b Anatomical relationships of organs in the thoracic cavity. Apex of lung Pulmonary artery Left main bronchus Left superior lobe Oblique fissure Pulmonary vein Left inferior lobe Cardiac impression Hilum of lung Oblique fissure Aortic impression Lobules Photograph of medial view of the left lung. © 2013 Pearson Education, Inc.
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Figure 22.11 A cast of the bronchial tree.
Right lung Left lung Right superior lobe (3 segments) Left superior lobe (4 segments) Right middle lobe (2 segments) Right inferior lobe (5 segments) Left inferior lobe (5 segments) © 2013 Pearson Education, Inc.
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Pulmonary circulation Low pressure, low resistance
Pulmonary arteries deliver systemic venous blood to lungs for oxygenation Pulmonary veins carry oxygenated blood from respiratory zones to heart Pulmonary capillary endothelium contains angiotensin-converting enzyme Converts angiotensin I to angiotensin II. (Renin converts angiotensinogen to Ang I.) © 2013 Pearson Education, Inc.
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Bronchial circulation Oxygenated blood for lung tissue
Only circulatory pathway that goes from systemic arteries to pulmonary veins © 2013 Pearson Education, Inc.
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Thin, double-layered serosa
Pleurae Thin, double-layered serosa Parietal pleura on thoracic wall, superior face of diaphragm, around heart, between lungs Visceral pleura on external lung surface Pleural fluid fills thin pleural cavity Provides lubrication and surface tension assists in expansion and recoil © 2013 Pearson Education, Inc.
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Organs in the thoracic cavity
Figure 22.10c Organs in the thoracic cavity Esophagus (in mediastinum) Posterior Vertebra Root of lung at hilum • Left main bronchus Right lung • Left pulmonary artery Parietal pleura • Left pulmonary vein Visceral pleura Left lung Pleural cavity Thoracic wall Pulmonary trunk Pericardial membranes Heart (in mediastinum) Anterior mediastinum Sternum Anterior Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown. © 2013 Pearson Education, Inc.
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Mechanics of Breathing
Pulmonary ventilation consists of two phases Inspiration-gases flow into lungs Expiration-gases exit lungs © 2013 Pearson Education, Inc.
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Pressure Relationships in the Thoracic Cavity
Atmospheric pressure (Patm) Pressure exerted by air surrounding body 760 mm Hg at sea level = 1 atmosphere Respiratory pressures described relative to Patm Negative respiratory pressure-less than Patm Positive respiratory pressure-greater than Patm Zero respiratory pressure = Patm © 2013 Pearson Education, Inc.
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Intrapulmonary Pressure
Intrapulmonary (intra-alveolar) pressure (Ppul) Pressure in alveoli Fluctuates with breathing Always eventually equalizes with Patm © 2013 Pearson Education, Inc.
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Intrapleural Pressure
Intrapleural pressure (Pip) Pressure in pleural cavity Fluctuates with breathing Always a negative pressure (<Patm and <Ppul) Fluid level must be minimal Pumped out by lymphatics If accumulates positive Pip pressure lung collapse © 2013 Pearson Education, Inc.
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Intrapleural Pressure
Negative Pip caused by opposing forces Two inward forces promote lung collapse Elastic recoil of lungs decreases lung size Surface tension of alveolar fluid reduces alveolar size One outward force tends to enlarge lungs Elasticity of chest wall pulls thorax outward © 2013 Pearson Education, Inc.
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Pressure Relationships
If Pip = Ppul or Patm lungs collapse (Ppul – Pip) = transpulmonary pressure Keeps airways open Greater transpulmonary pressure larger lungs © 2013 Pearson Education, Inc.
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Figure 22.12 Intrapulmonary and intrapleural pressure relationships.
Atmospheric pressure (Patm) 0 mm Hg (760 mm Hg) Parietal pleura Thoracic wall Visceral pleura Pleural cavity Transpulmonary pressure 4 mm Hg (the difference between 0 mm Hg and −4 mm Hg) – 4 Intrapleural pressure (Pip) −4 mm Hg (756 mm Hg) Lung Diaphragm Intrapulmonary pressure (Ppul) 0 mm Hg (760 mm Hg) © 2013 Pearson Education, Inc.
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Homeostatic Imbalance
Atelectasis (lung collapse) due to Plugged bronchioles collapse of alveoli Pneumothorax-air in pleural cavity From either wound in parietal or rupture of visceral pleura Treated by removing air with chest tubes; pleurae heal lung reinflates © 2013 Pearson Education, Inc.
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Pulmonary Ventilation
Inspiration and expiration Mechanical processes that depend on volume changes in thoracic cavity Volume changes pressure changes Pressure changes gases flow to equalize pressure © 2013 Pearson Education, Inc.
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Relationship between pressure and volume of a gas
Boyle's Law Relationship between pressure and volume of a gas Gases fill container; if container size reduced increased pressure Pressure (P) varies inversely with volume (V): P1V1 = P2V2 © 2013 Pearson Education, Inc.
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Inspiration Active process
Inspiratory muscles (diaphragm and external intercostals) contract Thoracic volume increases intrapulmonary pressure drops (to 1 mm Hg) Lungs stretched and intrapulmonary volume increases Air flows into lungs, down its pressure gradient, until Ppul = Patm © 2013 Pearson Education, Inc.
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Forced Inspiration Vigorous exercise, COPD accessory muscles (scalenes, sternocleidomastoid, pectoralis minor) further increase in thoracic cage size © 2013 Pearson Education, Inc.
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Changes in lateral dimensions (superior view) Sequence of events
Figure Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 1 Changes in lateral dimensions (superior view) Sequence of events Changes in anterior-posterior and superior-inferior dimensions Inspiratory muscles contract (diaphragm descends; rib cage rises). 1 Ribs are elevated and sternum flares as external intercostals contract. Thoracic cavity volume increases. 2 Lungs are stretched; intrapulmonary volume increases. 3 Inspiration External intercostals contract. Intrapulmonary pressure drops (to –1 mm Hg). 4 Air (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure). 5 Diaphragm moves inferiorly during contraction. © 2013 Pearson Education, Inc.
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Quiet expiration normally passive process
Inspiratory muscles relax Thoracic cavity volume decreases Elastic lungs recoil and intrapulmonary volume decreases pressure increases (Ppul rises to +1 mm Hg) Air flows out of lungs down its pressure gradient until Ppul = 0 Note: forced expiration-active process; uses abdominal (oblique and transverse) and internal intercostal muscles © 2013 Pearson Education, Inc.
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Changes in lateral dimensions (superior view) Sequence of events
Figure Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 1 Changes in lateral dimensions (superior view) Sequence of events Changes in anterior-posterior and superior-inferior dimensions Inspiratory muscles relax (diaphragm rises; rib cage descends due to recoil of costal cartilages). 1 Ribs and sternum are depressed as external intercostals relax. Thoracic cavity volume decreases. 2 Elastic lungs recoil passively; intrapulmonary Volume decreases. 3 Expiration External intercostals relax. Intrapulmonary pressure rises (to +1 mm Hg). 4 Air (gases) flows out of lungs down its pressure gradient until intrapulmonary pressure is 0. 5 Diaphragm moves superiorly as it relaxes. © 2013 Pearson Education, Inc.
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Intrapulmonary pressure. Pressure inside lung
Figure Changes in intrapulmonary and intrapleural pressures during inspiration and expiration. Inspiration Expiration Intrapulmonary pressure. Pressure inside lung decreases as lung volume increases during inspiration; pressure increases during expiration. Intrapulmonary pressure +2 atmospheric pressure (mm Hg) Pressure relative to Trans- pulmonary pressure –2 Intrapleural pressure. Pleural cavity pressure becomes more negative as chest wall expands during inspiration. Returns to initial value as chest wall recoils. –4 –6 Intrapleural pressure –8 Volume of breath. During each breath, the pressure gradients move 0.5 liter of air into and out of the lungs. Volume of breath 0.5 Volume (L) 5 seconds elapsed © 2013 Pearson Education, Inc.
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Physical Factors Influencing Pulmonary Ventilation
Three physical factors influence the ease of air passage and the amount of energy required for ventilation. Airway resistance Alveolar surface tension Lung compliance © 2013 Pearson Education, Inc.
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Relationship between flow (F), pressure (P), and resistance (R) is:
Airway Resistance Friction-major nonelastic source of resistance to gas flow; occurs in airways Relationship between flow (F), pressure (P), and resistance (R) is: ∆P - pressure gradient between atmosphere and alveoli (2 mm Hg or less during normal quiet breathing) Gas flow changes inversely with resistance © 2013 Pearson Education, Inc.
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Resistance usually insignificant
Airway Resistance Resistance usually insignificant Large airway diameters in first part of conducting zone Progressive branching of airways as get smaller, increasing total cross-sectional area Resistance greatest in medium-sized bronchi Resistance disappears at terminal bronchioles where diffusion drives gas movement © 2013 Pearson Education, Inc.
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Figure 22.15 Resistance in respiratory passageways.
Conducting zone Respiratory zone Medium-sized bronchi Resistance Terminal bronchioles 1 5 10 15 20 23 Airway generation (stage of branching) © 2013 Pearson Education, Inc.
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Homeostatic Imbalance
As airway resistance rises, breathing movements become more strenuous Severe constriction or obstruction of bronchioles Can prevent life-sustaining ventilation Can occur during acute asthma attacks; stops ventilation Epinephrine dilates bronchioles, reduces air resistance © 2013 Pearson Education, Inc.
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Alveolar Surface Tension
Attraction of liquid molecules for one another at gas-liquid interface Resists any force that tends to increase surface area of liquid Water has high surface tension Water layer on alveolar walls generates a “shrinking” (closing) force © 2013 Pearson Education, Inc.
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Alveolar Surface Tension
Surfactant Anything that reduces surface tension Type II alveolar cells make surfactant (lipd/protein mix) Reduces surface tension of alveolar fluid and discourages alveolar collapse Insufficient quantity in premature infants causes infant respiratory distress syndrome © 2013 Pearson Education, Inc.
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Lung Compliance Compliance = ΔV / ΔP ΔV = change in lung volume
ΔP = change in transpulmonary pressure © 2013 Pearson Education, Inc.
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High lung compliance easy to expand lungs Normally high, due to
Lung tissue that is easy to distend (stretch) Surfactant, which decreases alveolar surface tension Diminished by Scar tissue (which is inelastic) replacing lung tissue (fibrosis) Reduced production of surfactant Decreased flexibility of thoracic cage © 2013 Pearson Education, Inc.
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Lung Compliance Lung compliance is also influenced by compliance of the thoracic wall, which is decreased by: Deformities of thorax Ossification of costal cartilage Paralysis of intercostal muscles © 2013 Pearson Education, Inc.
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