Chapter 16 The respiratory system: pulmonary ventilation Overview of respiratory function 呼吸系統功能總論 Anatomy of the respiratory system 呼吸系統的解剖構造 Forces of pulmonary ventilation 肺臟換氣的力量 Factors affecting pulmonary ventilation 影響肺臟換氣的因素 Clinical significance of respiratory volumes and air flows 呼吸容積及空氣流速的臨床含意

I. Overview of Respiratory Function The respiratory system 呼吸系統 is so named because its function is respiration, the process of gas exchange 氣體交換的過程 This exchange of gases occurs at two levels, termed internal respiration 內呼吸 and external respiration 外呼吸 Internal respiration 內呼吸  the use of oxygen (O2) within mitochondria 粒線體 to generate ATP by oxidative phosphorylation 氧化磷酸化 External respiration 外呼吸  the exchanges of oxygen (O2) and carbon dioxide (CO2) between the atmosphere and body tissues, which involves both the respiratory and circulatory systems 循環系統 P454

External Respiration External respiration encompasses four processes: Pulmonary ventilation 肺臟換氣, the movement of air into the lungs (inspiration 吸氣) and out of the lungs (expiration 呼氣) by bulk flow 整體流 Exchange of oxygen (O2) and carbon dioxide (CO2) between lung air spaces and blood by diffusion Transportation of O2 and CO2 between the lungs and body tissues by the blood Exchange of O2 and CO2 between the blood and tissues by diffusion Figure 16.1 Relationship between external respiration and internal respiration. In external respiration,  air moves between the atmosphere and the lung,  oxygen and carbon dioxide are exchanged between lung tissue and the blood, oxygen and carbon dioxide are transported in the blood, and  oxygen and carbon dioxide are exchanged between systemic tissues and the blood. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P454-455

Internal Respiration Figure 16.1 Relationship between external respiration and internal respiration. Internal respiration is the use of oxygen and production of carbon dioxide by cells, primarily within the mitochondria. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. The internal respiration (or cellular respiration 細胞呼吸) refers to the use of oxygen (O2) within mitochondria to generate ATP by oxidative phosphorylation, and the production of carbon dioxide (CO2) as a waste product P454-455

I. Overview of Respiratory Function In addition to its main function—respiration—the respiratory system also performs several other functions, including contributing the regulation of acid-base balance in the blood enabling vocalization 使能發音 participating in defense against pathogens 致病原 and foreign particles 外來顆粒 in the airways providing a route for water and heat losses (via the expiration of air that was moistened and warmed during inspiration enhancing venous return (through the respiratory pump) activating certain plasma proteins (e.g. angiotensin I) as they pass through the pulmonary circulation P454

II. Anatomy of the Respiratory System Upper Airways 上呼吸道 鼻腔 口腔 會厭 聲門 咽 喉 食道 Respiratory System = upper airways + respiratory tract P455-456 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.2 Anatomy of the upper airways and the respiratory tract. The term upper airways 上呼吸道 refers to air passages 空氣通道 in the head 頭 and neck 頸 Air enters the nasal cavity and/or the oral cavity, both of which lead to the pharynx 咽, a muscular tube that serves as a common passageway for both air and food After the pharynx, air enters the first structure in the respiratory tract 呼吸道, the larynx 喉

Respiratory Tract The respiratory tract includes all air passageways leading from the pharynx 咽 to lungs  can be functionally divided into two components: a conducting zone 傳導區 and a respiratory zone 呼吸區域 The conducting zone, the upper part of the respiratory tract, functions in conducting air from the larynx to the lungs The respiratory zone, the lowermost part of the respiratory tract, contains the sites of gas exchange within the lungs P455-456 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

The Conducting Zone The conducting zone starts with larynx 喉, a tube held open by cartilage 軟骨 (a dense connective tissue) in its walls To keep food from entering the respiratory tract, the opening to the larynx, called the glottis 聲門, is covered by a flap of tissue 垂下的組織 called the epiglottis 會厭, which during swallowing 吞嚥 is forced down over the glottis and prevents food or water from entering the larynx The larynx houses the vocal cords (or vocal folds) 聲帶, which generate sounds by vibrating 振動 when air passes over them After the larynx, the next component of the respiratory tract is the trachea 氣管, a tube about 2.5 cm in diameter and 10 cm long that runs parallel with and anterior to the esophagus 食道 The trachea stays open because the front and sides of its wall contain 15-20 C-shaped bands of cartilage (C型軟骨) that provide structural rigidity This rigidity is important because without it, the decline in air pressure that occurs in the trachea during inspiration 吸氣 would collapse it and cut off the flow of air P455-456

The Conducting Zone After it enters the thoracic cavity 胸腔, the trachea 氣管 divides into left and right bronchi 支氣管(primary bronchi 主要支氣管) that conduct air to each lung  secondary bronchi 次級支氣管  tertiary bronchi 三級支氣管  bronchioles 細支氣管  terminal bronchioles 終末細支氣管 Unlike the larger bronchi, bronchioles 細支氣管 have no cartilage and are thus capable of collapsing 塌陷  to help prevent collapse, the walls of bronchioles contain elastic fibers 彈性纖維 The primary function of the conducting zone is to provide a passageway through which air can enter and exit the respiratory zone, where gas exchange occurs As air travels through the conducting zone, its temperature 溫度 is adjusted to body temperature and humidified 使濕潤的 to keep the respiratory tract moist P456-458 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

The Conducting Zone The epithelium 上皮細胞 lining the larynx and trachea (and to a lesser extent, the bronchi) contains numerous goblet cells 杯狀細胞 & also abundant in the epithelium throughout the conducting zone are ciliated cells 纖毛細胞 Goblet cells secrete a viscous fluid called mucus 黏液, which coats the airways and traps foreign particles in inhaled air The cilia 纖毛 (hair-like projections) of the ciliated cells beat in a whip-like fashion to propel 推動 the mucus containing the trapped particles up to toward the glottis 聲門 and then into the pharynx 咽, where the mucus is then swallowed 吞嚥  this process, called the mucus escalator 黏液自動升降梯 Smooth muscle is sparse 稀少 in the trachea and bronchi but increases in abundance 豐富 as the airways become smaller  the lack of cartilage and the presence of circular smooth muscle within the bronchioles enable these airways to change their diameter  such changes alter the resistance to air flow P458

The Conducting Zone Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.3 Anatomical features of the conducting and respiratory zones of the respiratory tract. 0 indicates not present 不存在, + indicates sparse 稀少, ++ indicates present 存在, and +++ indicates abundant 豐富. P457

The Respiratory Zone The first respiratory zone 呼吸區 structures, respiratory bronchioles 呼吸性 細支氣管, terminate in alveolar ducts 肺泡管道 , which lead to alveoli 肺泡, the primary structures where gas exchange occurs  most alveoli occur in clusters called alveolar sacs 肺泡囊 Adjacent alveoli are not completely independent structures  they are connected by alveolar pores 肺泡孔, air flows between alveoli, allowing equilibration of pressure within the lungs P459-460 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.5 Anatomy of the respiratory zones. (a) Structures in the respiratory zone, which begins where terminal bronchioles branch into respiratory bronchioles. Alveoli are shown both in clusters called alveolar sacs at the ends of alveolar ducts, and associated with alveolar ducts and respiratory bronchioles. (b) The dense capillary network surrounding alveoli.

The Respiratory Zone The alveolar wall contains type I alveolar cells, which make up the structure of the wall, and type II alveolar cells, which secrete surfactant 表面作用劑 & also found in alveoli are macrophage 巨噬細胞, which engulf foreign particles and pathogens inhaled into the lungs In many places in the lungs, the alveolar epithelial cells and the endothelial cells of the nearby capillaries are so close together that their basement membranes 基底膜 are fused  together, the capillary and the alveolar wall from a barrier, called the respiratory membrane that separates air from blood The thinness of the respiratory membranes—only about 0.2 mm thick— is essential for efficient gas exchange Figure 16.5 Anatomy of the respiratory zones. (c) The alveolar wall contains type I cells, which make up the structure of the wall, and type II cells, which secrete surfactant. Also found in alveoli are macrophages. (d) Enlargement of the respiratory membrane showing the close association between alveolar and capillary walls. P459-460 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

The Respiratory Zone Alveoli = site of gas exchange Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.3 Anatomical features of the conducting and respiratory zones of the respiratory tract. 0 indicates not present 不存在, + indicates sparse 稀少, ++ indicates present 存在, and +++ indicates abundant 豐富. P457 Alveoli = site of gas exchange 300 million alveoli/lung (tennis court size) Rich blood supply- capillaries form sheet over alveoli Alveolar pores

Structures of the Thoracic Cavity The chest wall 胸腔壁 is composed of structures that protect the lungs: the rib cage 肋骨籠 (consisting of 12 pairs of ribs), the sternum (breastbone) 胸骨, the thoracic vertebrae 胸椎, and associated muscles 相關的肌肉 and connective tissue 結締組織 (primarily hyaline cartilage 透明軟骨) Muscles of the chest wall, which are responsible for breathing, are the internal intercostals 內肋間肌 and external intercostals 外肋間肌, located between the ribs, and the diaphragm 橫隔膜, which seals off the lower end of the chest wall and separates the thoracic and abdominal cavities  the compartment enclosing the lungs is airtight 密閉的 The interior surface of the chest wall and the exterior surface of the lungs are lined by a membrane called the pleura 胸膜, which is composed of a layer of epithelial cells and connective tissue & each lung is surrounded by a separate pleural sac 胸膜囊 The side of the pleural sac attached to the lung tissue is called the visceral pleura 胸膜臟層 & the side attached to the chest wall is called the parietal pleura胸膜壁層  between the two pleurae is a very thin compartment called the intrapleural space 胸膜內隙, which is filled with a small volume (approximately 15 ml) of intrapleural fluid 胸膜內液 P459

Structures of the Thoracic Cavity 肋間肌 肋骨 胸膜囊 肋間肌 胸膜臟層 胸膜壁層 胸膜內隙 橫隔膜 胸膜囊 胸腔壁 (肋骨籠、胸骨、胸椎、結締組織、肋間肌) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.7 Chest wall and pleural sac. The chest wall includes the ribs, sternum, thoracic vertebrae, connective tissue, and intercostal muscles. The side of the pleural sac attached to the lung is called the visceral pleura & the side of the sac attached to the chest wall is called the parietal pleura. The fluid-filled intrapleural space is much thinner than shown here, with a total volume of approximately 15 ml. P461

III. Forces for Pulmonary Ventilation Pulmonary pressures Ventilation occurs because of the presence of pressure gradients 壓力梯度 between the alveoli and the outside air (atmosphere 大氣壓)  air moves from high to low pressure Inspiration 吸氣: pressure in lungs less than atmosphere Expiration 呼氣: pressure in lungs greater than atmosphere Four primary pressures are associated with ventilation: Atmospheric pressure (Patm) is the pressure of the outside air=760 mmHg Intra-alveolar pressure (Palv) 肺泡內壓 is the pressure of air within the alveoli  at rest, Palv=Patm; at inspiration, Palv<Patm; at expiration, Palv>Patm Intrapleural pressure (Pip) 胸膜內壓 is the pressure inside the pleural space  is always negative & always < Palv Transpulmonary pressure (Palv – Pip) 肺間壓 is the difference between the Pip and the Palv  is a measure of the distending force across the lungs P462-463

Copyright © 2008 Pearson Education, Inc Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Surface tension of intrapleural fluid hold wall and lungs together 胸膜內液的表面張力讓胸壁及肺臟可以連接在一起 Figure 16.8 Pleural pressure at rest. (a) Pulmonary pressure for a lung at rest. Intra-alveolar pressure is the pressure within the alveoli; intra-pleural pressure is the pressure in the pleural sac. Trans-pulmonary pressure is the difference between intra-alveolar pressure and intra-pleural sac. All pressures are given as absolute pressures and as pressures relative to atmospheric pressure. (b) Pressures and elastic forces when the lungs are at the functional residual capacity (between breaths). When the lungs are at rest all breathing muscles are relaxed, and the volume of air in the lungs under theses conditions is called the functional residual capacity (FRC)  at the FRC, Palv = Patm = 0 mmHg. The lung is distended 膨脹, and an elastic recoil force 彈力回彈的力量 tends to collapse it inward 往內塌陷 & the chest wall is compressed 壓縮, and an elastic recoil force tends to expand it outward 往外伸展. The net force these two opposing forces exert on the two sides of the pleural sac creates a negative intrapleural pressure (Pip). P462

Copyright © 2008 Pearson Education, Inc Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.9 Pneumothorax. (a) Normal intrapleural pressure at rest is -4 mmHg. Air entering the intrapleural space through a hole in the chest wall creates pneumothorax 氣胸. (b) As a consequence of pneumothorax, intrapleural pressure equilibrates with atmospheric pressure. Without the negative force of intrapleural pressure drawing the lung outward, the lung collapses 塌陷 due to elastic recoil forces. Trauma 外傷 is not the only possible cause of a pneumothorax  a spontaneous pneumothorax 自發性氣胸 occurs if disease damages the wall of the pleura adjacent to a bronchus or alveolus such that air from inside the lungs enters the intrapleural space Common diseases that may cause spontaneous pneumothorax include pneumonia 肺炎 and emphysema 肺氣腫 P463

Mechanics of Breathing Air flow into and out of the lungs is driven by pressure gradients that the muscles of respiration create by changing the volume of the lungs The relationship between pressure and volume follows Boyle’s law 波以耳定律, which states that for a given quantity of any gas (such as air) in an airtight container 密閉容器, the pressure is inversely 反比 related to the volume of the container Air flow into and out of the lungs also occurs by bulk flow 整體流, with the rate of flow determined by a pressure gradient (Patm- Palv) and resistance as follows: Because atmospheric pressure is constant 恆定的, changes in alveolar pressure determine the direction of air movement 空氣移動的方向 V1P1=V2P2 Patm – Palv Flow = R R = resistance to air flow Resistance related to radius of airways and mucus P463-464

Determinants of Intra-Alveolar Pressure 肺泡內壓的決定因素 Factors determining intra-alveolar pressure 肺泡內壓的決定因素 Quantity of air in alveoli 肺泡內空氣的量 Volume of alveoli 肺泡的體積 Lungs expand – alveolar volume increases 肺臟擴張-肺泡體積增加 Palv decreases 肺泡內壓下降 Pressure gradient drives air into lungs 壓力梯度驅動空氣進入肺臟 Lungs recoil – alveolar volume decreases 肺臟彈回-肺泡體積減少 Palv increases 肺泡內壓增加 Pressure gradient drives air out of lungs 壓力梯度驅動空氣流出肺臟 P464

Copyright © 2008 Pearson Education, Inc Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P465 Figure 16.10 Changes in alveolar pressure and breath volume during inspiration and expiration. Before inspiration, Palv is 0 mmHg. During inspiration, expansion of the lungs causes Palv to decrease. Air flow increases the quantity of gas in the lungs, which increases Palv. At the end of inspiration, Palv is equal to Patm. During expiration, the lungs collapse inward, causing Palv to increase. Air flows out of the lungs down a pressure gradient. At the end of expiration, Palv is equal to Patm, and air flow is zero.

Muscles of Respiration The changes in the volume of the alveoli are produced by changes in the volume of the thoracic cavity, which involve the respiratory muscles The diaphragm 橫膈肌 and the external intercostal muscles 外肋間肌 are the primary inspiratory 吸氣 muscles, whereas the internal intercostals 內肋間肌 and abdominal muscles 腹肌 are the primary expiratory 呼氣 muscles, although expiration is primarily a passive process not requiring any muscle contraction 外肋間肌 內肋間肌 橫膈膜 腹部的肌肉 呼氣肌 吸氣肌 Figure 16.11 Respiratory muscles. (a) Location of inspiratory and expiratory muscle. Notice the opposite origination of the external and internal intercostal muscles. P465-466 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Diaphragm & external intercostals increase volume of thoracic cavity Internal intercostals & abdominal muscles decrease volume of thoracic cavity

外肋間肌收縮 橫膈膜收縮 外肋間肌鬆弛 內肋間肌及腹部肌肉只有在主動呼吸時才會收縮 橫膈膜鬆弛 胸腔壁及肺臟擴張 胸腔及肺臟收縮 肋骨及胸骨壓迫 肋骨擴張使胸骨往上及往外移動 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.11 Respiratory muscles. (b) Action of respiratory muscles. When inspiratory muscles contract (at left), the chest wall expands, causing the lungs to expand. Quiet expiratory (at right) occurs passively by relaxation of the muscles of inspiratory, which allows the lungs and chest wall to recoil to their original positions. Active expiration requires contraction of the muscles of expiration, while the muscles of inspiration relax. P466

Inspiration 吸氣 These skeletal muscles are stimulated to contract by the release of acetylcholine at the neuromuscular junction P465 Figure 16.12 Events in the process of inspiration. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P467

Expiration 呼氣 During quiet breathing, expiration is a passive process in that it does not require muscle contraction A more forceful 強迫性的 expiration can be produced by contraction of the expiratory muscles in a process called active expiration 主動性呼氣 Expiration normally a passive process When inspiratory muscles stop contracting, recoil of lungs and chest wall to original positions decreases volume of thoracic cavity Active expiration requires expiratory muscles Contraction of expiratory muscles creates greater and faster decrease in volume of thoracic cavity P467-468

Figure 16.13 Volume and pressure changes during inspiration and expiration. (a) The difference between atmospheric and intra-alveolar pressure (the pressure gradient for ventilation) provides the force for moving air into or out of the lungs, and the transpulmonary pressure provides the force for expansion of the lung. (b) Changes in the intra-alveolar (Palv) and intra-pleural pressures (Pip) that occur during breathing are such that the transpulmonary pressure increases during inspiration and during the beginning of expiration, and then decreases as expiration continues. (c) Changes in breath volume indicate that Pip follows Boyle’s law (intrapleural space is a closed system), but Palv does not (alveoli are an open system due to movement of molecules in and out). P467 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

IV. Factors Affecting Pulmonary Ventilation The rate at which air flows into or out of the lungs is determined by two factors: the pressure gradient between the atmosphere and alveoli, and the airway resistance The various factors that affect development of those pressure gradients and factors that affect airway resistance Lung Compliance 肺臟的順應性 Airway Resistance 呼吸道的阻力 P468

Lung Compliance A measure of the ease with which lungs can be stretched is called compliance 測量肺臟可被拉張的(膨脹的)容易程度稱為適應性 Lung compliance is defined as the change volume (V) that results from a given change in transpulmonary pressure [(Palv – Pip)] Larger lung compliance  easier to inspire & smaller change in transpulmonary pressure needed to bring in a given volume of air 順應性愈大，愈容易吸氣，肺間壓的變化很小即可吸入一定量的空氣 Lung compliance depends on the elasticity of the lungs 肺臟的彈性 and on the surface tension of the fluid lining the alveoli 肺泡內液體的 表面張力 More elastic  less compliant 彈性愈大，順應性愈差 Greater tension  less compliant 表面張力愈大，順應性愈差 V Lung Compliance = (Palv – Pip) P468

Lung Compliance The surface tension 表面張力 of a liquid is a measure of the work required to increase its surface area by a certain amount The surface tension of the lungs is caused by the air-liquid interface 接觸面 formed by the thin layer of liquid lining the interface of the alveoli The presence of a detergent-like substance called pulmonary surfactant 界面活性劑 decrease the surface tension in alveoli is secreted by type II alveolar cells Surfactant interferes with the hydrogen bonding 氫鍵 between water molecules  surfactant increases lung compliance and decreases the work of breathing Compliance is decreased if lung tissue thickens, such as occurs with the formation of scar tissue in tuberculosis 肺結核, or if surfactant production is decreased, such as occurs in infant respiratory distress syndrome 新生兒呼吸窘迫症 P468

Airway Resistance The term airway resistance 呼吸道 阻力 refers to the resistance of the entire system of airways in the respiratory tract Airway resistance is determined primarily by resistances of individual airways and is affected most strongly by changes in airways radius 呼吸道 直徑的變化  as radius decreases, airway resistance increases During quiet breathing (eupnea) 平靜呼吸, the difference between alveolar and atmospheric pressure is generally less than 2 mmHg  when resistance increases, a larger pressure gradients is required Figure 16.14 Effects of increasing airway resistance on the pressure changes required to move a fixed volume of air. When airway resistance is increased over normal, a greater intra-alveolar pressure is required to move a given volume of air into and out of the lungs in a given period of time. P468,470

Airway Resistance The resistance to air flow is affected by a number of factors, including passive forces exerted on the airways, contractile activity of smooth muscle in the bronchioles 細支氣管平滑肌收縮活性, and secretion of mucus into the airways 分泌到呼吸道的黏液 The passive forces are responsible for changes in airway resistance that occur in a single breath  include changes in transpulmonary pressure 肺間壓 and tractive forces 牽引力 When this smooth muscle contracts, it decreases the radius of the bronchioles (called bronchoconstriction 支氣管縮小), which increases resistance  the contraction and relaxation of bronchiolar smooth muscle is subject to both extrinsic control外因性調控 (neural and hormonal signals) and intrinsic 內因性 control (local chemical mediators) Airway resistance can be increased in a number of pathological states, such as asthma 氣喘, chronic obstructive pulmonary diseases (COPD) 慢性阻塞性肺臟疾病, apnea 呼吸暫停 P470

Extrinsic control of bronchiole radius Autonomic nervous system 自律神經系統 Sympathetic 交感神經  relaxation of smooth muscle 平滑肌鬆弛 (bronchodilation 支氣管擴張) Parasympathetic 副交感神經  contraction of smooth muscle 平滑肌收縮 (bronchoconstriction 支氣管收縮) Hormonal control 荷爾蒙的調控 Epinephrine 腎上腺素 relaxation of smooth muscle 平滑肌 Intrinsic control of bronchiole radius Histamine 組織胺  bronchoconstriction 支氣管收縮 released during asthma 氣喘 and allergies 過敏 also increases mucus secretion 黏液分泌增加 Carbon dioxide 二氧化碳  bronchodilation 支氣管擴張 P470

Factors Affecting Lung Volume 影響肺臟體積的因素 Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings.

V. Clinical Significance of Respiratory Volumes and Air Flows Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Clinicians measure lung volumes 肺容積, calculate lung capacities 肺容量 (which are the sums of two or more measured lung volumes), and measures air flow rates 空氣流速 in order to gain information concerning pulmonary function Spirometry 肺計量測定法 is a technique for measuring the volumes of inspired and expired air using a device裝置 called spirometer 肺計量器 Figure 16.15 Spirometry. While a subject breathes air in and out, a pen attached via a pulley 滑輪 system records changes in the volume of air in the inverted bell. P471-472

Lung Volumes Using spirometry, clinicians can measure three of the four non-overlapping lung volumes 肺容積 that together make up the total lung capacity 總肺容量 The volume of air that moves into and out of the lungs during a single, unforced breath is called the tidal volume (VT) 潮氣容積  about 500 ml The maximum volume of air that can be inspired 吸入 from the end of normal inspiration 正常吸氣 is called the inspiratory reserve volume (IRV) 吸氣儲備容積  about 3000 ml The maximum volume of air can be expired 呼出 from the end of normal expiration 正常呼氣 is called expiratory reserve volume (ERV) 呼氣儲備容積  about 1000 ml The volume of air remaining 殘餘 in the lungs after a maximum expiration最大呼氣之後 is called the residual volume (RV) 肺餘容積  about 1200 ml & cannot be measured by spirometry P471,473

Lung Capacities Lung capacities 肺容量 are sums of two or more of the lung volume 肺容積  the inspiratory capacity (IC) 吸氣容量 is the maximum volume of air that can be inspired at the end of a resting expiration  IC=VT+IRV  about 3500 ml The vital capacity (VC) 肺活量 is the maximum volume of air that can be expired following a maximum inspiration  VC=VT+IRC+ERV  about 4500 ml The functional residual capacity (FRC) 功能肺餘容量 is the volume of air remaining in the lungs at the end of a tidal expiration  FRC=ERV+RV  about 2200 ml The total lung capacity (TLC) 總肺容量 is the volume of air in the lungs at the end of a maximum inspiration  TLC=VT+IRV+ERV+RV  about 5700 ml P473

Figure 16. 16 Lung volumes and capacities measured using spirometry Figure 16.16 Lung volumes and capacities measured using spirometry. The curves shown were produced by spirometry and represent average values for a 70-kg male. P472 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

補充自: Vander 人體生理學

Pulmonary Function Tests A simple measure of lung volumes and calculations of lung capacities can help distinguish between obstructive pulmonary diseases 阻塞性肺臟疾病, which involve increases in airway resistance 呼吸道阻力增加, and restrictive pulmonary disorders 限制性肺臟疾病, in which something interferes with lung expansion 肺臟擴張受到干擾 P473 The term obstructive pulmonary disease is an umbrella term for a number of diseases, all of which are characterized by increased airway resistance  including emphysema 肺氣腫, chronic bronchitis 慢性支氣管炎, and asthma 氣喘  whereas asthma is acute, the others are chronic Unlike asthma, chronic obstructive pulmonary disease (COPD) is chronic and progressive 漸進性的  such as emphysema and chronic bronchitis  is largely preventable 可預防的 because it is most often associated with cigarette smoking Emphysema is a permanent 永久性的 enlargement of airspaces in the respiratory zone accompanied by destruction of air walls  tissue destruction is a result of the action of proteases 蛋白水解酶, enzymes secreted by macrophages 巨噬細胞 and other white blood cells 白血球細胞 during chronic inflammation 慢性發炎 P471

Pulmonary Function Tests Chronic bronchitis is an inflammation of the airways that lasts for at least three months a year for at least two consecutive years It is characterized by inflammation and thickening of airway lining 呼吸道內層變厚, which reduces airway diameter and which can also lead to destruction of the normal tissue and fibrosis 纖維化 (thickening and scarring 結痂 by the formation of connective tissue) Treatments for COPD include bronchodilators 支氣管擴張劑 (such as b2 adrenergic receptor agonists) and anti-inflammatory drugs 消炎藥 (such as corticosteroids 類固醇) P471 Asthma, is associated with an increase in airway resistance caused by spastic contractions of the smooth muscle in bronchioles 細支氣管平滑肌痙攣性收縮coupled with increased mucus secretions 黏液分泌增加 and inflammation of the walls of the bronchioles Symptoms include coughing 咳嗽, dyspnea 呼吸困難, and wheezing 喘鳴  is often the result of hypersensitivity 過敏 to certain allergens 過敏原, such as fungi 黴菌, dust mites 塵螨, or animal danger 動物皮屑, but it can also be induced by stress, exercise, eating certain foods, or breathing cold air P470

Obstructive Pulmonary Diseases The residual volume often increases 肺餘容積通常增加 because an increase in resistance 呼吸道阻力增加 makes it harder not only to inspire, but also to expire The lungs become overinflated 過度膨脹 and the functional residual capacity功能肺餘容量 and total lung capacity總肺容量 are often increases Examples: asthma, COPD (such as emphysema, chronic bronchitis) Restrictive Pulmonary Diseases In contrast, restrictive disorders often involves structural damage to the lungs, pleura, or chest wall that decreases the total lung capacity 總肺容量and vital capacity 肺活量 Examples: pulmonary fibrosis 肺纖維化 P473

Forced Vital Capacity (FVC) 強迫肺活量 The forced vital capacity (FVC) is the person takes a maximum inspiration and then forcefully exhales 最大吸氣後用力呼出 as much and as rapidly as possible  a low FVC is indicates of restrictive pulmonary disease Forced Expiratory Volume (FEV) 強迫呼出最大氣體體積 The forced expiratory volume (FEV) is a measure of the percentage of the FVC that can be exhaled within a certain length of time, most commonly 1 second (FEV1) 測量在第一秒內能被呼出的肺活量的百分比 A normal FEV1 is 80%, meaning that a person should be able to exhale 80% of the forced vital capacity within 1 second  an FEV1 that is less than 80% is indicative of increase resistance, which is characteristic of obstructive pulmonary disease FEV1 = percent of FVC that can be exhaled within 1 second Normal FEV1 = 80% (If FVC = 4000 ml, should expire 3200 ml in 1 sec) FEV1 < 80% indicates obstructive pulmonary disease P473

Alveolar Ventilation Minute ventilation (VE) 每分鐘的換氣量, which is the total amount of air that flows into or out of the respiratory system in a minute  VE = VT x RR (respiratory rate, the numbers of breaths per minute)  about 6000 ml/min Only a portion of the air breathed in actually participates in gas exchange, because a significant fraction of the air simply fills up the volume of airways in the conducting zone The combined volume of these non-exchanging airways is referred to as the anatomical dead space 解剖死腔 Alveolar ventilation (VA or minute alveolar ventilation) 每分鐘肺泡的換氣量 is a measure of the volume of fresh air reaching the alveoli each minute  VA = (VT x RR) – (DSV x RR)  about 4200 ml/min Normal minute ventilation (VE) = 500 mL x 12 breaths/min = 6000 mL/min Normal Alveolar Ventilation = (500 mL/br x 12 br/min) – (150 mL/br X 12 br/min) = 4200 mL/min DSV: dead space volume  about 150 ml P473-474

Alveolar Ventilation Figure 16.17 The effects of anatomical dead space on alveolar ventilation. (a) At the end of expiration, all the air in the conducting and respiratory zones is stale 舊的air. (b) During inspiration, stale air from the conducting zone (anatomical dead space) enters the respiratory zone first, followed by atmospheric air. (c) During expiration, atmospheric air in the conducting zones is expired first, followed by stale. Air in conducting zone does not participate in gas exchange Thus, conducting zone = anatomical dead space Dead space voulme (DSV) approximately 150 mL Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P474

Alveolar Ventilation When respiration rate (RR) is increased, the dead space volume (DSV) is effectively subtracted out of each additional breath However, when tidal volume (VT) is increased, the total increase in volume in excess of the dead space volume (DSV) adds to the fresh air reaching the alveoli Therefore, it is more efficient to increasing alveolar ventilation (VA) by increasing tidal volume (VT) than by increasing respiration rate (RR) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. P474

Summary of Minute Ventilation Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings.