Fundamentals Of Anatomy & Physiology Chapter 23 PDF

Fundamentals of Anatomy & Physiology Eleventh Edition Chapter 23 The Respiratory System © 2018 Pearson Education, Inc.  Learning outcomes 23-1 Desc...

Fundamentals of Anatomy & Physiology Eleventh Edition Chapter 23 The Respiratory System © 2018 Pearson Education, Inc.  Learning outcomes 23-1 Describe the primary functions and organization of the respiratory system, and explain how the delicate respiratory exchange surfaces are protected from pathogens, debris, and other hazards. 23-2 Identify the organs of the upper respiratory system, and describe their functions. 23-3 Describe the structure of the larynx, discuss its roles in normal breathing and in sound production, and identify the structures of the airways. 23-4 Describe the functional anatomy of alveoli. 23-5 Describe the superficial anatomy of the lungs and the structure of a pulmonary lobule. 23-6 Define and compare the processes of external respiration and internal respiration. 2 © 2018 Pearson Education, Inc.  Learning outcomes 23-7 Summarize the physical principles controlling the movement of air into and out of the lungs, and describe the actions of the respiratory muscles. 23-8 Summarize the physical principles governing the diffusion of gases into and out of the blood and body tissues. 23-9 Describe the structure and function of hemoglobin, and the transport of oxygen and carbon dioxide in the blood. 23-10 List the factors that influence respiration rate, and discuss reflex respiratory activity and the brain centers involved in the control of respiration. 23-11 Describe age-related changes in the respiratory system. 23-12 Give examples of interactions between the respiratory system and other organ systems studied so far. 3 © 2018 Pearson Education, Inc.  An Introduction to the Respiratory System  Respiratory system – Cells obtain energy primarily through aerobic metabolism Requires oxygen and produces carbon dioxide – Oxygen is obtained from air by diffusion across exchange surfaces in lungs – Blood carries oxygen from lungs to peripheral tissues And carries carbon dioxide from peripheral tissues to lungs 4 © 2018 Pearson Education, Inc.  23-1 Components of the Respiratory System  Functions of respiratory system – Provide extensive surface area for gas exchange between air and circulating blood – Move air to and from exchange surfaces of lungs – Protect respiratory surfaces from dehydration, temperature changes, and pathogens – Produce sounds – Detect odors with olfactory receptors in nasal cavity 5 © 2018 Pearson Education, Inc.  23-1 Components of the Respiratory System  Organization of respiratory system – Upper respiratory system Nose, nasal cavity, paranasal sinuses, and pharynx – Lower respiratory system Larynx, trachea, bronchi, bronchioles, and alveoli 6 © 2018 Pearson Education, Inc. Figure 23–1 The Structures of the Respiratory System. Upper Respiratory System Nose Nasal cavity Sinuses Tongue Pharynx Esophagus Lower Respiratory System Clavicle Larynx Trachea Bronchus Lungs Bronchioles Respiratory bronchioles Ribs Right Left lung lung Diaphragm Alveoli 7  23-1 Components of the Respiratory System  Respiratory tract – Conducting portion From nasal cavity to larger bronchioles – Respiratory portion Smallest respiratory bronchioles and alveoli – Alveoli Air-filled pockets within lungs Where all gas exchange takes place 8 © 2018 Pearson Education, Inc.  23-1 Components of the Respiratory System  Respiratory mucosa – Lines conducting portion of respiratory system – Consists of An epithelium Areolar tissue layer (lamina propria) – Functions in the respiratory defense system A series of filtration mechanisms Removes particles and pathogens from inhaled air 9 © 2018 Pearson Education, Inc.  23-1 Components of the Respiratory System  Lamina propria – In upper respiratory system, trachea, and bronchi Contains mucous glands that discharge secretions onto epithelial surface – In conducting portion of lower respiratory system Contains smooth muscle cells that encircle lumen of bronchioles 10 © 2018 Pearson Education, Inc. Figure 23–2a The Respiratory Epithelium of the Nasal Cavity and Conducting Portion of the Respiratory Tract. Epithelial surface SEM × 1647 a The cilia of the epithelial cells form a dense layer that resembles a shag carpet. Ciliary movement propels mucus across the epithelial surface. 11 Figure 23–2b The Respiratory Epithelium of the Nasal Cavity and Conducting Portion of the Respiratory Tract. Movement of mucus Ciliated columnar to pharynx epithelial cell Mucous cell Stem cell Mucociliary escalator Mucous gland Mucus Lamina propria b A diagrammatic view of the respiratory epithelium of the trachea, showing the direction of mucus transport inferior to the pharynx. 12 Figure 23–2c The Respiratory Epithelium of the Nasal Cavity and Conducting Portion of the Respiratory Tract. Cilia Lamina propria Nucleus of columnar epithelial cell Mucous cell Basement membrane Stem cell c A sectional view of the respiratory epithelium, a pseudostratified ciliated columnar epithelium. 13  23-1 Components of the Respiratory System  Structure of respiratory epithelium – Nasal cavity and superior portion of pharynx Pseudostratified ciliated columnar epithelium ,numerous mucous cells – Inferior portions of pharynx Stratified squamous epithelium – Superior portion of lower respiratory system Pseudostratified ciliated columnar epithelium – Smaller bronchioles Cuboidal epithelium with scattered cilia – Alveolar epithelium Lines exchange surfaces of alveoli Very delicate, simple squamous epithelium Contains scattered, specialized cells 14 © 2018 Pearson Education, Inc.  23-1 Components of the Respiratory System  Respiratory defense system – Filtration in nasal cavity removes large particles – Mucous cells and mucous glands Produce mucus that bathes exposed surfaces – Cilia Sweep mucus and trapped debris and microorganisms toward pharynx to be swallowed – Alveolar macrophages Engulf small particles that reach lungs 15 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Nose – Primary passageway for air entering respiratory system – Air enters through nostrils (nares) Passes into nasal vestibule (space contained within flexible tissues of nose) – Nasal hairs In epithelium of vestibule Trap large particles in air 16 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Nasal cavity – Nasal septum Divides nasal cavity into left and right sides Anterior portion (hyaline cartilage) supports dorsum of nose and apex of nose – Superior portion of nasal cavity is olfactory region Provides sense of smell – Mucus produced in paranasal sinuses and tears Clean and moisten nasal cavity 17 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Air flows – From vestibule to choanae (openings of nasal cavity) – Through superior, middle, and inferior nasal meatuses – Meatuses are narrow passageways that produce air turbulence to Trap particles in mucus Warm and humidify incoming air Bring olfactory stimuli to olfactory receptors 18 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Palates – Hard palate Forms floor of nasal cavity Separates nasal and oral cavities – Soft palate Extends posterior to hard palate Divides superior nasopharynx from rest of pharynx 19 © 2018 Pearson Education, Inc. Figure 23–3a The Structures of the Upper Respiratory System. Dorsum of nose Nasal Apex cartilages of nose External nares a The nasal cartilages and external landmarks on the nose 20 Figure 23–3b The Structures of the Upper Respiratory System. Cranial cavity Frontal sinus Ethmoidal air cell Right eye Medial rectus muscle Lens Lateral rectus Superior muscle nasal concha Superior nasal meatus Middle nasal Nasal Septum concha Perpendicular Middle nasal plate of ethmoid meatus Vomer Maxillary sinus Inferior nasal Hard palate concha Tongue Inferior nasal meatus Mandible b A frontal section through the head, showing the meatuses and the maxillary sinuses and air cells of the ethmoidal labyrinth 21 Figure 23–3c The Structures of the Upper Respiratory System. Frontal sinus Nasal Conchae Nasal cavity Superior Middle Choanae Inferior Pharyngeal opening of auditory tube Nasal vestibule Pharyngeal tonsil Nostrils Pharynx Hard palate Nasopharynx Oral cavity Oropharynx Tongue Laryngopharynx Soft palate Palatine tonsil Mandible Epiglottis Lingual tonsil Hyoid bone Glottis Thyroid cartilage Cricoid cartilage Trachea Esophagus Thyroid gland c The nasal cavity and pharynx, as seen in sagittal section with the nasal septum removed 22  23-2 Upper Respiratory System  Nasal cavity opens into nasopharynx at choanae  Nasal mucosa – Warms and humidifies inhaled air for arrival at lower respiratory system – Breathing through mouth bypasses this important step  Nosebleed – Fairly common due to extensive vascularization of nasal cavity 23 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Pharynx – A chamber shared by digestive and respiratory systems – Extends between choanae and entrances to larynx and esophagus – Divided into three regions Nasopharynx Oropharynx Laryngopharynx 24 © 2018 Pearson Education, Inc.  23-2 Upper Respiratory System  Nasopharynx – Superior portion of pharynx – Contains pharyngeal tonsil and pharyngeal openings of auditory tubes  Oropharynx – Connects directly to oral cavity  Laryngopharynx – Inferior portion of pharynx – Between hyoid bone and entrance to larynx and esophagus 25 © 2018 Pearson Education, Inc.  23-3 Lower Respiratory System  Air flows from pharynx to larynx – Through glottis Slit-like opening between vocal cords  Three large, unpaired cartilages form the larynx – Thyroid cartilage – Cricoid cartilage – Epiglottis  Three pairs of smaller paired hyaline cartilages in larynx – Arytenoid cartilage – Corniculate cartilage – Cuneiform cartilage 26 © 2018 Pearson Education, Inc. Figure 23–4a The Anatomy of the Larynx. Epiglottis Lesser cornu Hyoid bone Median thyrohyoid ligament Laryngeal prominence Thyroid Larynx cartilage Median cricothyroid ligament Cricoid cartilage Cricotracheal ligament Trachea Tracheal cartilages a Anterior view 27 Figure 23–4b The Anatomy of the Larynx. Epiglottis Vestibular ligament Corniculate cartilage Vocal ligament Thyroid Arytenoid cartilage cartilage Cricoid cartilage Tracheal cartilages b Posterior view 28 Figure 23–4c The Anatomy of the Larynx. Hyoid bone Epiglottis Vestibular Thyroid ligament cartilage Corniculate cartilage Vocal ligament Arytenoid cartilage Cricoid Median cricothyroid cartilage ligament Cricotracheal ligament Tracheal cartilages ANTERIOR POSTERIOR c Sagittal section 29  23-3 Lower Respiratory System  Ligaments of larynx – Vestibular ligaments and vocal ligaments Extend between thyroid cartilage and arytenoid cartilages Covered by folds of laryngeal epithelium – Vestibular ligaments lie within vestibular folds Protect delicate vocal folds of glottis Vocal folds are involved with production of sound, so are also known as vocal cords 30 © 2018 Pearson Education, Inc.  23-3 Lower Respiratory System  Sound production – Air passing through glottis vibrates vocal folds Producing sound waves – Voluntary muscles reposition arytenoid cartilages Control tension of vocal folds Altering pitch of sound – Speech is produced by Phonation—sound production at larynx Articulation—sound modification with lips, tongue, and teeth 31 © 2018 Pearson Education, Inc. Figure 23–5a The Glottis and Surrounding Structures. Corniculate cartilage POSTERIOR Cuneiform cartilage Ary-epiglottic Vestibular fold fold Vocal fold Epiglottis Root of tongue ANTERIOR a Glottis in the closed position. 32 Figure 23–5b The Glottis and Surrounding Structures. POSTERIOR Corniculate cartilage Cuneiform cartilage Glottis (open) Rima glottidis Vocal fold Vestibular fold Epiglottis ANTERIOR b Glottis in the open position. 33 Figure 23–5c The Glottis and Surrounding Structures. Corniculate cartilage Cuneiform cartilage Glottis (open) Rima glottidis Vocal fold Vestibular fold Vocal nodule (abnormal) Epiglottis c Photograph taken with a laryngoscope positioned within the oropharynx, superior to the larynx. Note the abnormal vocal nodule. 34  23-3 Lower Respiratory System  Trachea (windpipe) – Tough, flexible tube – Extends from cricoid cartilage to mediastinum Branches into right and left main bronchi – Submucosa Thick layer of connective tissue Surrounds mucosa Contains tracheal glands that produce mucous secretions 35 © 2018 Pearson Education, Inc.  23-3 Lower Respiratory System  Trachea – Contains 15–20 C-shaped tracheal cartilages Stiffen tracheal walls and protect airway Discontinuous where trachea contacts esophagus, allowing distortion of tracheal wall when swallowing – Ends of each tracheal cartilage are connected by Elastic anular ligament Trachealis muscle 36 © 2018 Pearson Education, Inc. Figure 23–6a The Anatomy of the Trachea. Hyoid bone Larynx Trachea Tracheal cartilages Carina of trachea Root of right lung Root of left lung Lung tissue Main bronchi Lobar Right bronchi lung Left lung a A diagrammatic anterior view showing the plane of section for part (b) 37 Figure 23–6b The Anatomy of the Trachea. Esophagus Anular ligament Trachealis Respiratory epithelium Lumen of trachea Tracheal gland Tracheal cartilage b A cross-sectional view of the trachea and esophagus 38 38  23-3 Lower Respiratory System  Bronchial tree – Right main bronchus and left main bronchus Each divides to form lobar bronchi that supply lobes of lungs Lobar bronchi branch to form segmental bronchi – Each segmental bronchus Supplies air to one bronchopulmonary segment – Right lung has 10 – Left lung has 8 or 9  Carina of trachea – Ridge that separates openings of right and left main bronchi at their junction with trachea 39 © 2018 Pearson Education, Inc. Figure 23–7a The Bronchi, Lobules, and Alveoli of the Lung. RIGHT LEFT Bronchopulmonary segments of superior lobe Bronchopulmonary (3 segments) segments of superior lobe (4 segments) Broncho- Broncho- pulmonary pulmonary segments of segments of middle lobe inferior lobe (2 segments) (5 segments) Broncho- pulmonary segments of inferior lobe (5 segments) a Anterior view of the lungs, showing the bronchial tree and its divisions 40 Figure 23–7b The Bronchi, Lobules, and Alveoli of the Lung. Trachea Cartilage plates Left main bronchus Visceral pleura Lobar bronchus Segmental bronchi Smaller bronchi Bronchioles Terminal bronchiole Alveoli in a Respiratory pulmonary bronchiole lobule Bronchopulmonary segment b The branching pattern of bronchi in the left lung, simplified 41 Figure 23–7c The Bronchi, Lobules, and Alveoli of the Lung. Respiratory epithelium Branch of pulmonary artery Bronchiole Bronchial artery (red), vein (blue), and nerve (yellow) Smooth muscle around terminal bronchiole Terminal bronchiole Respiratory bronchiole Arteriole Lymphatic Capillary beds vessel Alveolar duct Bands of Branch of Interlobular septum elastic fibers pulmonary vein Alveolar sac Alveoli c The structure of a single pulmonary lobule, part of a bronchopulmonary segment 42  23-3 Lower Respiratory System  Bronchial structure – Walls of main, lobar, and segmental bronchi Contain progressively less cartilage and more smooth muscle Degree of smooth muscle tension affects bronchial diameter and resistance to airflow  Bronchitis – Inflammation and constriction of bronchi and bronchioles due to infection Causes breathing difficulty 43 © 2018 Pearson Education, Inc.  23-3 Lower Respiratory System  Bronchioles – Each segmental bronchus branches into multiple bronchioles – Bronchioles branch into terminal bronchioles Each segmental bronchus forms about 6500 terminal bronchioles – Bronchioles have no cartilage Dominated by smooth muscle 44 © 2018 Pearson Education, Inc.  23-3 Lower Respiratory System  Autonomic nervous system – Controls luminal diameter of bronchioles by regulating smooth muscle – Controls airflow in lungs  Bronchodilation – Caused by sympathetic activation – Enlarges luminal diameter of airway – Reduces resistance to airflow  Bronchoconstriction – Reduces luminal diameter of airway – Caused by Parasympathetic activation Histamine release (allergic reactions) 45 © 2018 Pearson Education, Inc.  23-4 Gas Exchange Structures  Each terminal bronchiole branches to form several respiratory bronchioles – Respiratory bronchioles are connected to alveoli along alveolar ducts – Alveolar ducts end at alveolar sacs Common chambers connected to many individual alveoli – Each alveolus has an extensive network of capillaries Surrounded by elastic fibers 46 © 2018 Pearson Education, Inc. Figure 23–8a Alveolar Organization and the Blood Air Barrier. Alveolar Respiratory bronchiole duct Smooth muscle Alveolus Bands of elastic fibers Alveolar sac Capillaries a The basic structure of the distal end of a single lobule. A network of capillaries, supported by bands of elastic fibers, surrounds each alveolus. Respiratory bronchioles are also wrapped by smooth muscle cells that can change the diameter of these airways. 47 Figure 23–8b Alveolar Organization and the Blood Air Barrier. Alveoil Respiratory bronchiole Alveolar sac Al ve ol ar Arteriole du ct Histology of the lung LM × 14 b Low-power micrograph of lung tissue. 48  23-4 Gas Exchange Structures  Alveolar cell layer – Consists mainly of simple squamous epithelium Formed by thin, delicate pneumocytes type I Site of gas exchange Patrolled by alveolar macrophages – Contains large, scattered pneumocytes type II that produce surfactant 49 © 2018 Pearson Education, Inc. Figure 23–8c Alveolar Organization and the Blood Air Barrier. Pneumocyte Pneumocyte type II type I Alveolar macrophage Elastic fibers Alveolar macrophage Capillary Endothelial cell of capillary c A diagrammatic view of alveolar structure. A single capillary may be involved in gas exchange with several alveoli simultaneously. 50  23-4 Gas Exchange Structures  Surfactant – Oily secretion – Contains phospholipids and proteins – Coats alveolar surface and reduces surface tension  Respiratory distress syndrome – Alveoli collapse after each exhalation – Caused by inadequate amounts of surfactant due to injury or genetic abnormalities 51 © 2018 Pearson Education, Inc.  23-4 Gas Exchange Structures  Gas exchange occurs across blood air barrier of alveoli – Consists of three layers Alveolar cell layer Capillary endothelial layer Fused basement membrane between them 52 © 2018 Pearson Education, Inc. Figure 23–8d Alveolar Organization and the Blood Air Barrier. Red blood cell Capillary lumen Capillary Nucleus of endothelium endothelial cell 0.5 µm Fused Alveolar Surfactant basement cell layer membrane Alveolar air space d The blood air barrier. 53  23-4 Gas Exchange Structures  Gas exchange across blood air barrier is quick and efficient – Because distance for diffusion is short – And O2 and CO2 are small and lipid soluble  Pneumonia – Inflammation of lung tissue – Causes fluid to leak into alveoli – Compromises function of blood air barrier 54 © 2018 Pearson Education, Inc.  23-5 The Lungs  Left and right lungs – In left and right pleural cavities – Inferior portion (base) rests on diaphragm  Lobes of lungs are separated by deep fissures – Right lung has three lobes Superior, middle, and inferior Separated by horizontal and oblique fissures – Left lung has two lobes Superior and inferior Separated by oblique fissure 55 © 2018 Pearson Education, Inc.  23-5 The Lungs  Right lung – Wider than left lung – Displaced upward by liver  Left lung – Longer than right lung – Indented on medial margin forming cardiac notch 56 © 2018 Pearson Education, Inc.  23-5 The Lungs  Hilum – Where pulmonary vessels, nerves, and lymphatics enter lung  Root of the lung – Complex of dense connective tissue, nerves, and vessels in hilum Anchored to mediastinum 57 © 2018 Pearson Education, Inc. Figure 23–9a The Gross Anatomy of the Lungs. Boundary between right and left Superior lobe pleural cavities Left lung Right lung Superior lobe Horizontal fissure Oblique fissure Middle lobe Fibrous layer Oblique fissure of pericardium Inferior lobe Inferior lobe Falciform ligament Cut edge of diaphragm Liver, Liver, a Thoracic cavity, anterior view right lobe left lobe 58 Figure 23–9b The Gross Anatomy of the Lungs. b Lateral Views The curving anterior and Apex Apex inferior borders follow the contours of the rib cage. Superior lobe Anterior border Horizontal fissure Superior lobe Middle Oblique fissure lobe Oblique Cardiac notch fissure Inferior lobe Inferior Base lobe Inferior border Base Right lung Left lung 59 Figure 23–9c The Gross Anatomy of the Lungs. c Medial Views The mediastinal surface, which contains the hilum, has an irregular shape. Both Apex Apex lungs have grooves that mark the Superior Bronchus Superior position of the great vessels and the lobe Groove lobe heart. for aorta The hilum of the lung Pulmonary Pulmonary artery is a groove that allows artery passage of the main Pulmonary veins bronchi, pulmonary Pulmonary vessels, nerves, and veins Horizontal fissure Inferior lymphatics. lobe Middle Oblique lobe Inferior fissure Oblique fissure Bronchus lobe Base Base Diaphragmatic surface Inferior border Right lung Left lung 60 Figure 23–10 The Relationship between the Lungs and Heart. Pericardial Body of sternum cavity Right lung, Ventricles middle lobe Oblique fissure Rib Left lung, Right pleural superior lobe cavity Visceral pleura Atria Left pleural cavity Esophagus Parietal pleura Aorta Bronchi Right lung, inferior lobe Mediastinum Spinal cord Left lung, inferior lobe 61  23-5 The Lungs  Trabeculae – Fibrous partitions in lungs – Contain elastic fibers, smooth muscles, and lymphatic vessels – Branch repeatedly, dividing lobes into ever-smaller compartments – Pulmonary lobules are divided by the finest partitions (interlobular septa) 62 © 2018 Pearson Education, Inc.  23-5 The Lungs  Blood supply to lungs – Respiratory exchange surfaces receive deoxygenated blood from pulmonary arteries – A capillary network surrounds each alveolus – Oxygen-rich blood from alveolar capillaries is carried through pulmonary veins to left atrium – Capillaries supplied by bronchial arteries provide oxygen and nutrients to conducting passageways 63 © 2018 Pearson Education, Inc.  23-5 The Lungs  Blood pressure in pulmonary circuit – Lower than that in systemic circuit – Pulmonary vessels are easily blocked by blood clots, fat, or air bubbles – Pulmonary embolism A blocked branch of pulmonary artery that stops blood flow to lobules or alveoli 64 © 2018 Pearson Education, Inc.  23-5 The Lungs  Two pleural cavities – Separated by mediastinum – Each pleural cavity contains a lung Cavity is lined with serous membrane (pleura)  Pleura – Consists of two layers Parietal pleura (lines inner surface of thoracic wall) Visceral pleura (covers outer surfaces of lungs) – Pleural fluid Lubricates space between the two layers 65 © 2018 Pearson Education, Inc.  23-6 External and Internal Respiration  Respiration includes two integrated processes – External respiration All processes involved in exchange of O2 and CO2 with external environment – Internal respiration Uptake of O2 and release of CO2 by cells Result of cellular respiration 66 © 2018 Pearson Education, Inc.  23-6 External and Internal Respiration  Integrated steps in external respiration – Pulmonary ventilation (breathing) – Gas diffusion Across blood air barrier in lungs Across capillary walls in other tissues – Transport of O2 and CO2 Between alveolar capillaries Between capillary beds in other tissues 67 © 2018 Pearson Education, Inc. Figure 23–11 An Overview of the Key Steps in Respiration. Respiration External Respiration Internal Respiration Pulmonary ventilation O2 transport Tissues Gas Gas diffusion diffusion Lungs Gas Gas diffusion diffusion CO2 transport 68  23-6 External and Internal Respiration  Abnormal external respiration is dangerous – Hypoxia Low tissue oxygen levels – Anoxia Complete lack of oxygen in tissues 69 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Pulmonary ventilation (breathing) – Physical movement of air into and out of respiratory tract – Provides alveolar ventilation  Atmospheric pressure (atm) – Weight of Earth’s atmosphere Has several important physiological effects 70 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Boyle’s law – Defines the relationship between gas pressure and volume P = 1/V – In a contained gas External pressure forces molecules closer together Movement of gas molecules exerts pressure on container 71 © 2018 Pearson Education, Inc. Figure 23–12 The Relationship between Gas Pressure and Volume. a If you decrease the volume of the container, collisions occur more often per unit of time, increasing the pressure of the gas. b If you increase the volume, fewer collisions occur per unit of time, because it takes longer for a gas molecule to travel from one wall to another. As a result, the gas pressure inside the container decreases. 72  23-7 Pulmonary Ventilation  Pressure and airflow to lungs – Air flows from an area of higher pressure to an area of lower pressure – Respiratory cycle consists of An inspiration (inhalation) An expiration (exhalation) – Pulmonary ventilation causes volume changes that create changes in pressure Volume of thoracic cavity changes with expansion or contraction of diaphragm or rib cage 73 © 2018 Pearson Education, Inc. Figure 23–13 Pulmonary Ventilation (Part 1 of 4). Ribs and As the diaphragm is sternum contracted or the rib elevate cage (ribs and ster- num) is elevated, the volume of the thoracic cavity increases and air moves into the Diaphragm lungs. The anterior contracts movement of the ribs and sternum as they are elevated resembles the outward swing of a raised bucket handle. 74 Figure 23–13 Pulmonary Ventilation (Part 2 of 4). AT REST Thoracic wall Parietal pleura Pleural fluid Lung Visceral pleura Mediastinum Pleural cavity Right Left lung lung Diaphragm Poutside = Pinside When the rib cage and diaphragm are at rest, the pressures inside and outside the lungs are equal, and no air movement occurs. 75 Figure 23–13 Pulmonary Ventilation (Part 3 of 4). INHALATION Accessory Respiratory Muscles Sternocleidomastoid Scalenes Pectoralis minor Serratus anterior Primary Respiratory Muscles External intercostal muscles Diaphragm Elevation of the rib cage and contraction of the diaphragm increase the volume of the thoracic cavity. Pressure within the lungs decreases, Thoracic cavity volume increases and air flows in. Poutside > Pinside 76 Figure 23–13 Pulmonary Ventilation (Part 4 of 4). EXHALATION Accessory Respiratory Muscles Transversus thoracis Internal intercostal muscles Rectus abdominis When the rib cage returns to its original position and the diaphragm relaxes, the volume of the thoracic cavity decreases. Pressure Thoracic cavity volume decreases within the lungs increases, Poutside < Pinside and air moves out. 77  23-7 Pulmonary Ventilation  Primary respiratory muscles – The diaphragm – External intercostals  Accessory respiratory muscles – Activated when respiration increases significantly  Mechanics of breathing – Inhalation is always active – Exhalation can be active or passive 78 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Muscles used in inhalation – The diaphragm Contraction draws air into lungs Contributes 75 percent of normal air movement – External intercostal muscles Assist inhalation Contribute 25 percent of normal air movement – Accessory muscles assist in elevating ribs Sternocleidomastoid, scalenes, pectoralis minor, and serratus anterior 79 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Muscles used in exhalation – Internal intercostal muscle and transversus thoracis Depress the ribs – Abdominal muscles Compress abdomen Force diaphragm upward 80 © 2018 Pearson Education, Inc. Figure 23–14 Primary and Accessory Respiratory Muscles. Accessory Primary Respiratory Muscles Respiratory Muscles Sternocleidomastoid External intercostal muscles Scalenes Accessory Pectoralis minor Respiratory Muscles Internal intercostal Serratus anterior muscles Transversus thoracis Primary External oblique Respiratory Muscles Diaphragm Rectus abdominis Internal oblique 81  23-7 Pulmonary Ventilation  Respiratory movements are classified by pattern of muscle activity – Quiet breathing – Forced breathing  Forced breathing (hyperpnea) – Involves active inhalation and exhalation – Assisted by accessory muscles 82 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Quiet breathing (eupnea) – Involves active inhalation and passive exhalation – Diaphragmatic breathing or deep breathing Dominated by diaphragm – Costal breathing or shallow breathing Dominated by rib cage movements  Elastic rebound – When muscles of inhalation relax Elastic components of tissues recoil Diaphragm and rib cage return to original positions 83 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Pressure changes during inhalation and exhalation – Can be measured inside or outside lungs – Normal atmospheric pressure 1 atmosphere (atm) = 760 mm Hg 84 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Intrapulmonary pressure – Also called intra-alveolar pressure – Difference from atmospheric pressure determines direction of airflow – In relaxed breathing, pressure differential is small –1 mm Hg on inhalation or +1 mm Hg on exhalation – Breathing at maximum capacity (e.g., when lifting weights) can increase pressure gradient From –30 mm Hg during inhalation to +100 mm Hg while straining with glottis closed 85 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Intrapleural pressure – Pressure in space between parietal and visceral pleurae – Averages –4 mm Hg Maximum of –18 mm Hg during powerful inhalation – Remains below atmospheric pressure throughout respiratory cycle – Cyclical changes in intrapleural pressure create respiratory pump Assists in venous return to heart 86 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Pneumothorax – Air enters pleural cavity – Due to injury to chest wall or rupture of alveoli – Results in atelectasis (collapsed lung) 87 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Resistance – Adjusted with bronchodilation and bronchoconstriction  Compliance – A measure of expandability – Lower compliance requires greater force to fill lungs – Factors that affect compliance Connective tissue of lungs Level of surfactant production Mobility of thoracic cage 88 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Respiratory rates and volumes – Respiratory system adapts to changing oxygen demands by varying Number of breaths per minute (respiratory rate) Amount of air moved per breath (tidal volume, VT) – Respiratory minute volume (VE) Amount of air moved per minute Calculated as: respiratory rate × tidal volume Measures pulmonary ventilation 89 © 2018 Pearson Education, Inc. Figure 23–15 Pressure and Volume Changes during Inhalation and Exhalation. INHALATION EXHALATION Intrapulmonary +2 Trachea pressure (mm Hg) +1 0 a Changes in intrapulmonary pressure during a single –1 respiratory cycle Bronchi Intrapleural –2 Lung pressure (mm Hg) –3 Diaphragm –4 b Changes in intrapleural pressure during a single –5 respiratory cycle –6 Right pleural Left pleural cavity cavity Tidal volume (mL) 500 250 c A plot of tidal volume, the amount of air moving into and out of the lungs during a single respiratory cycle 0 1 2 3 4 Time (sec) 90  23-7 Pulmonary Ventilation  Only some inhaled air reaches alveolar exchange surfaces – Volume of air remaining in conducting passages is anatomic dead space (VD)  Alveolar ventilation – Amount of air reaching alveoli each minute – Calculated as respiratory rate × (tidal volume – anatomic dead space) – Alveoli contain less O2 than atmospheric air because inhaled air mixes with “used” air 91 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Relationships among VT, and – For a given respiratory rate, Increasing tidal volume increases alveolar ventilation rate – For a given tidal volume, Increasing respiratory rate increases alveolar ventilation rate 92 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Respiratory performance and volume relationships – Pulmonary function tests Measure rates and volumes of air movements – Total lung volume is divided into a series of volumes and capacities Measured with a spirometer 93 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Pulmonary volumes – Tidal volume (VT) Amount of air moved into or out of lungs in a breath – Expiratory reserve volume (ERV) Additional amount of air capable of being exhaled – Residual volume Amount of air in lungs after maximal exhalation Minimal volume (in a collapsed lung) – Inspiratory reserve volume (IRV) Additional amount of air that can be inhaled 94 © 2018 Pearson Education, Inc.  23-7 Pulmonary Ventilation  Respiratory capacities – Inspiratory capacity Tidal volume + inspiratory reserve volume – Functional residual capacity (FRC) Expiratory reserve volume + residual volume – Vital capacity Expiratory reserve volume + tidal volume + inspiratory reserve volume – Total lung capacity Vital capacity + residual volume 95 © 2018 Pearson Education, Inc. Figure 23–16 Pulmonary Volumes and Capacities. Pulmonary Volumes and Capacities (adult male) 6000 Sex Differences Tidal volume Inspiratory Inspiratory (VT = 500 mL) reserve capacity Males Females volume (IRV) VT 500 mL 500 mL IRV 3300 mL 1900 mL ERV 1000 mL 700 mL Vital capacity Residual Volume 1200 mL 1100 mL Total lung capacity 6000 mL 4200 mL Volume (mL) Vital capacity 4800 mL 3100 mL 2700 Total lung Inspiratory capacity 3800 mL 2400 mL capacity Functional residual capacity 2200 mL 1800 mL 2200 Expiratory reserve volume (ERV) Functional residual 1200 capacity (FRC) Residual volume Minimal volume (30–120 mL) 0 Time 96  23-8 Gas Exchange  Gas exchange – Occurs between blood and alveolar air – Across blood air barrier  Depends on – Partial pressures of gases involved – Diffusion of molecules between gas and liquid 97 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Diffusion of gases – Occurs in response to concentration gradients – Rate of diffusion depends on physical principles, or gas laws Example: Boyle’s law 98 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Dalton’s law – Each gas contributes to total pressure in proportion to its relative abundance  Partial pressure – Pressure contributed by a single gas in a mixture – In atmospheric air (760 mm Hg) Nitrogen (N2) is 78.6 percent (597 mm Hg) Oxygen (O2) is 20.9 percent (159 mm Hg) Water vapor (H2O) is 0.5 percent (3.7 mm Hg) Carbon dioxide (CO2) is 0.04 percent (0.3 mm Hg) 99 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Diffusion between liquids and gases – Henry’s law At a given temperature, amount of a gas in solution is proportional to partial pressure of that gas When gas under pressure contacts a liquid, pressure forces gas molecules into solution At equilibrium – Gas molecules diffuse out of liquid as quickly as they enter it – Number of gas molecules in solution is constant 100 © 2018 Pearson Education, Inc. Figure 23–17 Henry’s Law and the Relationship between Solubility and Pressure. Example Soda is put into the can under pressure, and the gas (carbon dioxide) is in solution at equilibrium. a Increasing the pressure drives gas molecules into solution until an equilibrium is established. Example Opening the can of soda relieves the pressure, and bubbles form as the dissolved gas leaves the solution. b When the gas pressure decreases, dissolved gas molecules leave the solution until a new equilibrium is established. 101  23-8 Gas Exchange  Solubility of gases in body fluids – CO2 is highly soluble – O2 is somewhat less soluble – N2 has very limited solubility  Partial pressures in plasma of pulmonary vein – PCO2 = 40 mm Hg – PO2 = 100 mm Hg – PN2 = 573 mm Hg 102 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Diffusion of gases across blood air barrier – Direction and rate of diffusion are determined by differing partial pressures and solubilities 103 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Reasons for efficiency of gas exchange – Differences in partial pressure across blood air barrier are substantial – Distances involved in gas exchange are short – O2 and CO2 are lipid soluble – Total surface area is large – Blood flow and airflow are coordinated 104 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  External respiration – Blood arriving in pulmonary arteries has Low PO2 High PCO2 – Concentration gradient causes O2 to enter blood CO2 to leave blood – Rapid exchange allows blood and alveolar air to reach equilibrium 105 © 2018 Pearson Education, Inc.  23-8 Gas Exchange  Internal respiration – Oxygenated blood mixes with deoxygenated blood from conducting passageways – Lowers PO2 of blood entering systemic circuit to about 95 mm Hg – Interstitial fluid PO2 40 mm Hg, PCO2 45 mm Hg – Concentration gradient in peripheral capillaries is opposite of lungs CO2 diffuses into blood, O2 diffuses out of blood 106 © 2018 Pearson Education, Inc. Figure 23–18a A Summary of Respiratory Processes and Partial Pressures in Respiration. a External Respiration PO2 = 40 Alveolus Pulmonary PCO2 = 45 circuit Blood air barrier PO = 100 Systemic O2 2 circuit PCO = 40 2 Diffusion CO 2 Pulmonary (alveolar) capillary PO2 = 100 PCO = 40 2 107 Figure 23–18b A Summary of Respiratory Processes and Partial Pressures in Respiration. Pulmonary circuit Systemic circuit b Internal Respiration Interstitial fluid PO = 95 2 PCO = 40 2 PO = 40 O 2 2 PCO = 45 2 CO Diffusion 2 Systemic PO = 40 2 capillary PCO = 45 2 108  23-9 Gas Transport  Gas transport – Blood plasma cannot transport enough O2 or CO2 to meet physiological needs – Red blood cells (RBCs) Transport O2 to, and CO2 from, peripheral tissues Remove O2 and CO2 from plasma, allowing gases to continue to diffuse into blood 109 © 2018 Pearson Education, Inc.  23-9 Gas Transport  Oxygen transport – O2 binds to iron ions in hemoglobin (Hb) molecules In a reversible reaction Forming oxyhemoglobin (HbO2) – Each RBC has about 280 million Hb molecules Each Hb molecule can bind four oxygen molecules 110 © 2018 Pearson Education, Inc.  23-9 Gas Transport  Hemoglobin saturation – Percentage of heme units containing bound oxygen at any given moment  Factors affecting Hb saturation – PO2 of blood – Blood pH – Temperature – Metabolic activity within RBCs 111 © 2018 Pearson Education, Inc.  23-9 Gas Transport  Oxygen–hemoglobin saturation curve – A graph relating hemoglobin saturation to partial pressure of oxygen Higher PO2 results in greater Hb saturation – Curve rather than a straight line because Hb changes shape each time a molecule of O2 binds Each O2 bound makes next O2 bind more easily 112 © 2018 Pearson Education, Inc.  23-9 Gas Transport  Oxygen–hemoglobin saturation curve – Standardized for normal conditions (pH 7.4, 37ºC) – When pH drops or temperature rises More oxygen is released Curve shifts to right – When pH rises or temperature drops Less oxygen is released Curve shifts to left 113 © 2018 Pearson Education, Inc. Figure 23–19 An Oxygen-Hemoglobin Saturation Curve. 100 90 80 Oxyhemoglobin (% saturation) 70 PO2 % saturation 60 (mm Hg) of Hb 10 13.5 50 20 35 30 57 40 40 75 50 83.5 30 60 89 70 92.7 20 80 94.5 90 96.5 100 97.5 10 0 20 40 60 80 100 PO2 (mm Hg) 114  23-9 Gas Transport  Hemoglobin and pH – Bohr effect—the effect of pH on hemoglobin saturation curve – Caused by CO2 – CO2 diffuses into RBCs Carbonic anhydrase catalyzes reaction with H2O Producing carbonic acid (H2CO3), which dissociates into hydrogen ion (H+) and bicarbonate ion (HCO3–) Hydrogen ions diffuse out of RBC, lowering pH 115 © 2018 Pearson Education, Inc. Figure 23–20a The Effects of Blood pH and Temperature on Hemoglobin Saturation. 100 80 Oxyhemoglobin (% saturation) 7.6 7.4 7.2 60 40 Normal blood pH range 20 7.35–7.45