A&P Ch21 Lecture Pearson PDF

21 The Respiratory System Lecture Presentation by Lori Garrett © 2018 Pearson Education, Inc.  Note to the Instructor: For the third editi...

21 The Respiratory System Lecture Presentation by Lori Garrett © 2018 Pearson Education, Inc.  Note to the Instructor: For the third edition of Visual Anatomy & Physiology, we have updated our PowerPoints to fully integrate text and art. The pedagogy now more closely matches that of the textbook. The goal of this revised formatting is to help your students learn from the art more effectively. However, you will notice that the labels on the embedded PowerPoint art are not editable. You can easily import editable art by doing the following: Copying slides from one slide set into another You can easily copy the Label Edit art into the Lecture Presentations by using either the PowerPoint Slide Finder dialog box or Slide Sorter view. Using the Slide Finder dialog box allows you to explicitly retain the source formatting of the slides you insert. Using the Slide Finder dialog box in PowerPoint: 1. Open the original slide set in PowerPoint. 2. 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Slides will place immediately after the slide you have selected in the Slides tab in Normal view. © 2018 Pearson Education, Inc.  Section 1: Anatomy of the Respiratory System Learning Outcomes 21.1 Identify the structures of the respiratory system, and list its major functions. 21.2 Explain how the delicate respiratory exchange surfaces are protected from pathogens, debris, and other hazards, and describe cystic fibrosis. 21.3 Identify the organs and structures of the upper respiratory system, and describe their functions. 21.4 Describe the structure of the larynx, and discuss its role in normal breathing and in the production of sound. © 2018 Pearson Education, Inc.  Section 1: Anatomy of the Respiratory System Learning Outcomes (continued) 21.5 Discuss the structures and functions of the airways outside and inside the lungs. 21.6 Describe the superficial anatomy of the lungs. 21.7 Describe the structure of a pulmonary lobule and the functional anatomy of the alveoli. © 2018 Pearson Education, Inc.  Module 21.1: The respiratory system has an upper and lower respiratory tract with different functions Respiratory System  Structures involved in breathing (pulmonary ventilation) Airflow to/from the lungs Gas exchange © 2018 Pearson Education, Inc.  Module 21.1: Upper and lower respiratory system Respiratory System (continued)  Respiratory tract—Branching passageway, carries air to/from gas exchange surfaces of the lungs  2 divisions of respiratory tract 1. Conducting portion—Nasal cavity to larger bronchioles 2. Respiratory portion—Smallest bronchioles to alveoli – Where gas exchange occurs © 2018 Pearson Education, Inc.  Module 21.1: Upper and lower respiratory system Upper respiratory system  Upper respiratory tract Filters, warms, and humidifies incoming air Protects delicate lower tract Reabsorbs heat and water in outgoing air © 2018 Pearson Education, Inc.  Module 21.1: Upper and lower respiratory system Lower respiratory system  Lower respiratory tract Conducts air to and from gas exchange surfaces © 2018 Pearson Education, Inc.  Anatomical components of the respiratory system © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc.  Module 21.1: Review A. Where does gas exchange between air and the lungs occur? B. Distinguish between the conducting portion and respiratory portion of the respiratory tract. Learning Outcome: Identify the structures of the respiratory system, and list its major functions. © 2018 Pearson Education, Inc.  Module 21.2: The respiratory defense system protects the respiratory mucosa Respiratory defense system—series of filtration mechanisms  Respiratory mucosa lines nasal cavity through large bronchioles Pseudostratified ciliated columnar epithelium with mucous cells Lamina propria = underlying areolar tissue; supports respiratory epithelium; has mucous glands in trachea and bronchi © 2018 Pearson Education, Inc.  Module 21.2: Respiratory defense system Mucociliary escalator  Flow of mucus/trapped debris  Sticky mucus produced by mucous cell and mucous glands  Traps debris particles  Moved by beating cilia  Swept toward pharynx Swallowed (to acids in stomach) or coughed out Epithelial stem cells replace damaged/old cells © 2018 Pearson Education, Inc.  Respiratory defense system © 2018 Pearson Education, Inc.  Module 21.2: The respiratory defense system Epithelia of the respiratory tract  Specific type varies along the respiratory tract  Respiratory mucosa Lines the nasal cavity and superior pharynx Also lines the superior portion of the lower respiratory tract  Stratified squamous epithelium Lines inferior portions of pharynx  Simple squamous epithelium Forms gas exchange surfaces Distance between air and blood in capillaries is less than 1 µm © 2018 Pearson Education, Inc.  The structure of the respiratory epithelium changes markedly along the respiratory tract © 2018 Pearson Education, Inc.  Module 21.2: Respiratory defense system Cystic fibrosis (CF)  Most common lethal inherited disease in individuals of Northern European descent  Mucosa produces thick mucus that cannot be transported  Mucociliary escalator stops clearing debris/pathogens; causes frequent infections (for example, Pseudomonas aeruginosa)  Average lifespan for people with CF who live to adulthood is 37  Death generally from heart failure and chronic bacterial lung infection © 2018 Pearson Education, Inc.  Module 21.2: Review A. Define respiratory defense system. B. What membrane lines the conducting portion of the respiratory tract? C. Why can cystic fibrosis become lethal? Learning Outcome: Explain how the delicate respiratory exchange surfaces are protected from pathogens, debris, and other hazards, and describe cystic fibrosis. © 2018 Pearson Education, Inc.  Module 21.3: The upper respiratory system includes the nose, nasal cavity, paranasal sinuses, and pharynx Nose is primary route for air entering respiratory system  Dorsum of nose (bridge) formed by two nasal bones Supported by hyaline cartilage  Nasal cartilages—small, elastic cartilages extending laterally from bridge; help keep nostrils open  Nostrils (external nares) are paired openings into nasal cavity © 2018 Pearson Education, Inc.  Module 21.3: Upper respiratory system Structures of the nasal cavity  Superior, middle, inferior nasal conchae (bones)  Superior, middle, and inferior nasal meatuses Passages between nasal conchae Swirl incoming air to trap small particles Moves chemicals to olfactory receptors Warms/humidifies air © 2018 Pearson Education, Inc.  Module 21.3: Upper respiratory system Paranasal sinuses  Frontal sinus, ethmoidal air cells, maxillary sinus, sphenoidal sinus  Mucus secreted by sinuses moistens/cleans nasal cavity surfaces; drains (with tears) through nasolacrimal duct Nasal septum—formed by vomer and perpendicular plate of ethmoid © 2018 Pearson Education, Inc.  Module 21.3: Upper respiratory system Lamina propria of nasal cavity has extensive network of veins  Release heat to warm inhaled air  Water from mucus evaporates to humidify inhaled air  Air moving from nasal cavity to lungs Heated to almost body temperature Nearly saturated with water vapor  The reverse process occurs during exhalation— mucosa reabsorbs heat and water; reduces heat loss and water loss to environment  Mouth breathing eliminates these benefits © 2018 Pearson Education, Inc.  Module 21.3: Upper respiratory system Pharynx—shared by respiratory and digestive systems 1. Nasopharynx—superior part; to soft palate Has pharyngeal opening of the auditory tube 2. Oropharynx—soft palate to base of tongue Stratified squamous epithelium 3. Laryngopharynx— hyoid to larynx Trachea (windpipe)— to bronchi © 2018 Pearson Education, Inc.  Module 21.3: Upper respiratory system  Nasal vestibule = space at front of nasal cavity Coarse hairs trap large airborne particles  Nasal cavity opens into nasopharynx through the choanae  Bony hard palate forms floor of nasal cavity Separates nasal/oral cavities  Soft palate—fleshy part posterior to hard palate  Glottis—opening into larynx  Larynx—mostly cartilage; surrounds/protects glottis  Trachea conducts air toward lungs © 2018 Pearson Education, Inc.  Sagittal section of the head and neck © 2018 Pearson Education, Inc.  Module 21.3: Review A. List the structures of the upper respiratory system. B. Trace the pathway of air through the upper respiratory system. C. Why is the vascularization of the nasal cavity important? Learning Outcome: Identify the organs and structures of the upper respiratory system, and describe their functions. © 2018 Pearson Education, Inc.  Module 21.4: The larynx protects the glottis that produces sounds Larynx  Cartilaginous tube; surrounds/protects glottis (“voice box”)  Three large cartilages: epiglottis, thyroid cartilage, cricoid cartilage © 2018 Pearson Education, Inc.  Module 21.4: The larynx Large laryngeal cartilages (continued) 1. Epiglottis—projects superior to glottis; forms lid over it – Swallowing—larynx elevates; epiglottis folds back over glottis; blocks entry into respiratory tract © 2018 Pearson Education, Inc.  Module 21.4: The larynx Large laryngeal cartilages (continued) 2. Thyroid cartilage (thyroid, shield shaped) – Prominent anterior surface is laryngeal prominence (Adam’s apple) – Thyrohyoid ligament attaches it to hyoid bone; other ligaments attach it to epiglottis and smaller cartilages © 2018 Pearson Education, Inc.  Module 21.4: The larynx Large laryngeal cartilages (continued) 3. Cricoid cartilage (ring shaped) – Forms complete ring around larynx – With thyroid cartilage, protects glottis and larynx; provides attachment for laryngeal muscles/ligaments © 2018 Pearson Education, Inc.  Module 21.4: The larynx Small paired laryngeal cartilages 1. Cuneiform cartilages—within folds of tissue between each arytenoid cartilage and the epiglottis 2. Corniculate cartilages articulate with arytenoid cartilages Work with the arytenoid to open/close the glottis 3. Arytenoid (ladle–shaped) cartilages articulate with superior surface of cricoid cartilage Larynx, posterior view, disarticulated © 2018 Pearson Education, Inc.  Anterior, sagittal, and posterior views of the larynx © 2018 Pearson Education, Inc.  Module 21.4: The larynx Glottis—where air passes through larynx  Made of vocal folds and rima glottidis (opening between folds)  Vocal folds = tissue folds that contain vocal ligaments Vibrations produce sound waves Opened/closed by rotation of arytenoid cartilages Also known as the vocal cords © 2018 Pearson Education, Inc.  Module 21.4: The larynx Glottis (continued)  Vestibular folds contain vestibular ligaments; prevent foreign objects from entering glottis © 2018 Pearson Education, Inc.  Module 21.4: The larynx Phonation = sound production from larynx  Vibration of vocal cords produces sound waves Articulation = modification of sounds by tongue, teeth, and lips  Amplification and resonance occur in pharynx, oral and nasal cavities, and paranasal sinuses © 2018 Pearson Education, Inc.  Module 21.4: Review A. Identify the paired and unpaired cartilages that compose the larynx. B. Describe the structures of the glottis. C. Distinguish between phonation and articulation. Learning Outcome: Describe the structure of the larynx, and discuss its role in normal breathing and in the production of sound. © 2018 Pearson Education, Inc.  Module 21.5: The trachea, bronchi, and bronchial branches convey air to and from lung gas exchange surfaces Trachea (windpipe)  Tough, flexible tube—starts at C6 and ends at T5 by branching into bronchi  Has 15–20 C-shaped tracheal cartilages Prevent collapse and overexpansion © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches Right and left main bronchi  Go to lungs  Right bronchus wider than left and at a steeper angle— foreign objects in trachea often go into it © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches  Ends of each C-shaped tracheal cartilage connected by elastic ligament and trachealis (muscle) Contraction of trachealis narrows trachea; restricts airflow Tracheal diameter changes often, mostly controlled by sympathetic stimulation— increases airflow Tracheal cartilages are incomplete posteriorly— allows expansion when swallowing © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches Bronchioles  No cartilage; thick smooth muscle  Sympathetic nervous system causes bronchodilation— increases airflow  Parasympathetic nervous system causes bronchoconstriction Decreases airflow © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches Bronchioles (continued)  Extreme bronchoconstriction can occur during allergic reactions such as asthma  Terminal bronchioles lead to pulmonary lobules (gas exchange)  Respiratory bronchioles are last division © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches Airflow and diameter changes  Trachea—larynx to main bronchi in mediastinum  Main bronchi—one to each lung; cartilage rings are complete  Lobar bronchi—3 in right lung, 2 in left; one per lobe  Segmental bronchi branch to give rise to bronchioles © 2018 Pearson Education, Inc.  Module 21.5: Trachea, bronchi, bronchial branches Airflow and diameter changes (continued)  Bronchioles → terminal bronchioles → respiratory bronchioles → pulmonary lobules  Bronchi branch into smaller and smaller tubes; diameter decreases with each new branch © 2018 Pearson Education, Inc.  Module 21.5: Review A. Compare the two main bronchi. B. What function do the C-shaped tracheal cartilages allow? C. Trace the pathway of airflow along the passages of the lower respiratory tract. Learning Outcome: Discuss the structures and functions of the airways outside and inside the lungs. © 2018 Pearson Education, Inc.  Module 21.6: The lungs have lobes that are subdivided into bronchopulmonary segments Gross anatomy of the lungs  Each lung divided into lobes Right lung (3): superior lobe, middle lobe, inferior lobe Left lung (2): superior lobe and inferior lobe  Each lobe has multiple bronchopulmonary segments Bronchial tree refers to all levels of bronchi through bronchioles  Each segmental bronchus ultimately supplies a bronchopulmonary segment © 2018 Pearson Education, Inc.  Lobes and Bronchopulmonary segments of the lungs © 2018 Pearson Education, Inc.  Anterior view of human lungs © 2018 Pearson Education, Inc.  Module 21.6: Gross anatomy of the lungs  Each lung is cone shaped and divided into lobes by deep fissures Right lung—horizontal fissure between superior/middle lobes; oblique fissure between middle/inferior lobes Left lung—oblique fissure between superior/inferior lobes © 2018 Pearson Education, Inc.  Module 21.6: Gross anatomy of the lungs  Apex (tip) extends to superior border of first rib  Concave base rests on diaphragm  Cardiac notch—left lung; accommodates pericardium/heart © 2018 Pearson Education, Inc.  Module 21.6: Gross anatomy of the lungs  Root of the lung—dense connective tissue; fixes positions of bronchi, major nerves, blood vessels, and lymphatics  Hilum is a medial depression on each lung Allows passage of main bronchus, pulmonary vessels, nerves, lymphatics  Grooves on surface of lungs mark positions of great vessels © 2018 Pearson Education, Inc.  Module 21.6: Review A. Define bronchopulmonary segment. B. Describe the location of the lungs within the thoracic cavity. C. Describe the lung borders and landmarks. D. Name the lobes and fissures of each lung. Learning Outcome: Describe the superficial anatomy of the lungs. © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules contain alveoli, where gas exchange occurs  Segmental bronchus supplies a bronchopulmonary segment  Bronchioles branch into terminal bronchioles in each bronchopulmonary segment  Each terminal bronchiole supplies a single pulmonary lobule  Terminal bronchioles branch to respiratory bronchioles  Respiratory bronchioles lead to alveolar ducts, which lead to alveolar sacs (alveolar saccules) © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Pulmonary alveoli (singular, alveolus)  ~150 million alveoli per lung; give lungs an open, spongy appearance  Surrounded by extensive capillary network for gas exchange © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Pulmonary alveoli (continued)  Surrounded by elastic fibers—expansion/recoil aids air movement  Each alveolar duct ends in clusters of alveoli (alveolar sacs, or alveolar saccules) © 2018 Pearson Education, Inc.  Divisions of the bronchial tree © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Pleurae—serous membrane sacs surrounding the lungs  Visceral pleura covers outer surfaces of lungs  Parietal pleura covers inner surface of thoracic wall; extends over diaphragm and mediastinum © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Pleurae (continued)  Pleural cavity—potential space between visceral and parietal layers of pleural sac Contains pleural fluid—reduces friction © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Alveolar epithelium  Three major cell types 1. Pneumocytes type I—thin, delicate, sites of gas diffusion 2. Pneumocytes type II produce surfactant—oily secretion; reduces surface tension of water in alveoli to prevent collapse © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Alveolar epithelium (continued) 3. Roaming alveolar macrophages locate and phagocytize particles that could clog the alveoli © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Blood air barrier—where gas exchange occurs between blood and alveolar air  Three layers: 1. Alveolar cell layer (epithelium) 2. Fused basement membranes (alveolar and capillary) 3. Capillary endothelium © 2018 Pearson Education, Inc.  Module 21.7: Pulmonary lobules and the respiratory membrane Very rapid diffusion  Minimal distance separating air and blood (average ~0.5 µm)  Both oxygen and carbon dioxide are lipid soluble © 2018 Pearson Education, Inc.  Module 21.7: Review A. Define pulmonary lobule. B. Describe the structure and function of the blood air barrier. C. What would happen to the alveoli if surfactant were not produced? Learning Outcome: Describe the structure of a pulmonary lobule and the functional anatomy of the alveoli. © 2018 Pearson Education, Inc.  Section 2: Respiratory Physiology Learning Outcomes 21.8 Describe external respiration and internal respiration. 21.9 Summarize the physical principles governing the movement of air into and out of the lungs. 21.10 Name the respiratory muscles, describe their actions, and define the various pulmonary function tests. 21.11 Explain how respiratory rate and tidal volume affect pulmonary and alveolar ventilation. © 2018 Pearson Education, Inc.  Section 2: Respiratory Physiology Learning Outcomes (continued) 21.12 Summarize the physical principles governing the diffusion of gases into and out of the blood. 21.13 Discuss the structure and function of hemoglobin, explain the oxygen-hemoglobin saturation curve, and describe the role of 2,3-bisphosphoglycerate. 21.14 Describe how carbon dioxide is transported in the blood, and explain how oxygen is picked up, transported, and released into the bloodstream. 21.15 Clinical Module: Explain how pulmonary disease affects compliance and resistance. © 2018 Pearson Education, Inc.  Section 2: Respiratory Physiology Learning Outcomes (continued) 21.16 Describe the brainstem structures that influence the control of respiration. 21.17 Identify and discuss reflex respiratory activity in pulmonary ventilation. 21.18 Clinical Module: Describe age-related changes to, and the effects of cigarette smoking on, the respiratory system. © 2018 Pearson Education, Inc.  Module 21.8: Respiratory physiology involves external and internal respiration Respiration  Two integrated processes: external respiration and internal respiration © 2018 Pearson Education, Inc.  Module 21.8: External and internal respiration Respiration (continued)  External respiration = exchange of gases between blood, lungs, and external environment; gas diffusion occurs across blood air barrier between alveolar air and alveolar capillaries Pulmonary ventilation (breathing)—air movement in/out of lungs – Maintains alveolar ventilation—air movement in/out of alveoli © 2018 Pearson Education, Inc.  Module 21.8: External and internal respiration Respiration (continued) Internal respiration—occurs between blood and tissues  Absorption of oxygen from blood  Release of carbon dioxide by tissue cells © 2018 Pearson Education, Inc.  Module 21.8: External and internal respiration Abnormalities affecting external respiration affect gas concentrations in interstitial fluids and cellular activities  Hypoxia = low tissue oxygen levels Severely limits metabolic activities  Anoxia = no oxygen supply Much of damage caused by heart attacks and strokes is the result of localized anoxia © 2018 Pearson Education, Inc.  Module 21.8: Review A. Define external respiration, gas diffusion, and internal respiration. B. How are hypoxia and anoxia different? Learning Outcome: Describe external respiration and internal respiration. © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation is driven by pressure changes within the pleural cavities Gas volume and pressure  Molecules in a gas bounce around independently When contained, collisions with container wall cause pressure More collisions = more pressure More collisions occur when molecules are in smaller container – Pressure is inversely related to volume (P = 1/V) – Relationship called Boyle’s law ↑ Volume causes ↓ Pressure ↓ Volume causes ↑ Pressure © 2018 Pearson Education, Inc.  Decreasing the container’s volume increases the number of molecular collisions, which increases the pressure © 2018 Pearson Education, Inc.  Increasing the container’s volume decreases the number of molecular collisions, which decreases the pressure © 2018 Pearson Education, Inc.  Summary of Boyle’s Law © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation Changing volume of the thoracic cavity  Movements of the diaphragm and rib cage change the volume of the thoracic cavity, which expands or compresses the lungs (changes lung volume)  Change in volume = change in pressure © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation Start of a breath:  Pressures inside and outside thorax are identical; no air movement  Expanding thoracic cavity expands lungs Parietal pleura attached to thoracic wall; visceral pleura to lungs Pleural fluid forms bond between layers If injury allows air into pleural cavity, bond is broken – Lung collapses (atelectasis) © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation Air flows from an area of higher pressure to an area of lower pressure  During inhalation Thoracic cavity enlarges Increased volume causes decreased pressure (Poutside > Pinside) Air moves in from an area of high pressure to low pressure © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation During exhalation  Thoracic cavity decreases in volume  Decreased volume causes increased pressure (Poutside < Pinside)  Air is forced out from an area of high pressure to low pressure © 2018 Pearson Education, Inc.  Volume and pressure changes during pulmonary ventilation © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation Direction of airflow determined by difference between:  Atmospheric pressure—pressure of air around us; and  Intrapulmonary pressure— pressure inside respiratory tract, usually measured at the alveoli © 2018 Pearson Education, Inc.  Module 21.9: Pulmonary ventilation Tidal volume = volume of air moved into and out of lungs in normal breath  Inhalation Intrapulmonary pressure < atmospheric pressure Negative intrapulmonary pressure pulls air into lungs  Exhalation Intrapulmonary pressure > atmospheric pressure Positive intrapulmonary pressure pushes air out of lungs © 2018 Pearson Education, Inc.  Summary of volume and pressure changes during pulmonary ventilation © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc.  Module 21.9 Review A. Define Boyle’s law. B. What physical changes affect the volume of the lungs? C. What pressures determine the direction of airflow within the respiratory tract? Learning Outcome: Summarize the physical principles governing the movement of air into and out of the lungs. © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles are involved with breathing, and… Respiratory muscles  May be involved with inhalation (inspiratory muscles) or exhalation (expiratory muscles)  Quiet breathing Active inhalation via inspiratory muscles Passive exhalation—done by elastic recoil of tissues and gravity, not by muscle action  Expiratory muscles are used when needed to force exhalation  Primary respiratory muscles—involved in inhalation  Accessory respiratory muscles—assist primary inspiratory muscles or provide active exhalation © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Inspiratory muscles  Primary inspiratory muscles—diaphragm, external intercostals Diaphragm does ~75 percent of movement – Flattens floor of thoracic cavity External intercostals do ~25 percent of movement; elevate ribs © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Inspiratory muscles (continued)  Accessory inspiratory muscles Sternocleidomastoid Scalenes Pectoralis minor Serratus anterior Increase speed/amount of rib movement to move more air when needed (tissue oxygen demands not met by primary inspiratory muscles) © 2018 Pearson Education, Inc.  Anterior view of primary and accessory inspiratory muscles © 2018 Pearson Education, Inc.  Lateral view of inspiratory muscles © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Expiratory muscles  There are no primary expiratory muscles— exhalation usually is passive process done by elastic recoil and gravity © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Accessory expiratory muscles  Internal intercostals, transversus thoracis, external oblique, internal oblique, rectus abdominis  Internal intercostals and transversus thoracis depress ribs  Abdominal muscles push diaphragm upward  Decrease thoracic cavity volume quickly  Allow greater pressure change and faster airflow out of lungs © 2018 Pearson Education, Inc.  Anterior view of accessory expiratory muscles © 2018 Pearson Education, Inc.  Lateral view of accessory expiratory muscles © 2018 Pearson Education, Inc.  Module 21.10:... and pulmonary function tests determine lung performance Pulmonary function tests monitor respiratory function by measuring rates/volumes of air movement  Respiratory volumes Tidal volume (VT) – Amount of air moved in or out of lungs during single respiratory cycle at rest (normal quiet breathing) – Averages 500 mL Inspiratory reserve volume (IRV) – Amount of air you can breathe in beyond tidal volume © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Respiratory volumes (continued)  Expiratory reserve volume (ERV) Amount of air you can exhale beyond tidal volume (after normal exhalation)  Residual volume Amount of air left in lungs after maximal exhalation  Minimal volume Amount of air in the lungs if they were allowed to collapse Included in residual volume Cannot be measured in a healthy person © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Respiratory capacities—calculated by taking sum of various respiratory volumes:  VT = tidal volume, IRV = inspiratory reserve volume, ERV = expiratory reserve volume  Inspiratory capacity: VT + IRV Amount of air you can inhale after normal exhalation  Vital capacity: ERV + VT + IRV Maximum amount of air you can move in or out of lungs per cycle © 2018 Pearson Education, Inc.  Module 21.10: Respiratory muscles and pulmonary function Respiratory capacities (continued)  Functional residual capacity (FRC): ERV + residual volume Amount of air remaining in lungs after complete quiet cycle  Total lung capacity: Vital capacity + residual volume Total volume of lungs Averages 6000 mL in adult males, 4200 mL in adult females © 2018 Pearson Education, Inc.  Respiratory volumes and capacities (in an average adult male) © 2018 Pearson Education, Inc.  Sex differences in respiratory volumes and capacities © 2018 Pearson Education, Inc.  Module 21.10 Review A. Identify the primary inspiratory muscles. B. When do the accessory respiratory muscles become active? C. Name the various measurable pulmonary volumes. Learning Outcome: Name the respiratory muscles, describe their actions, and define the various pulmonary function tests. © 2018 Pearson Education, Inc.  Module 21.11: Pulmonary ventilation must be closely regulated to meet tissue oxygen demands Pulmonary ventilation adjusts to meet body’s changing oxygen needs  Varies number of breaths/minute (respiratory rate) and volume moved per breath (tidal volume—VT) Respiratory rate (f)= Number of breaths/minute  Normal adult resting range: 12–18 breaths/minute  Average for children: 18–20 breaths/minute © 2018 Pearson Education, Inc.  Module 21.11: Variations in ventilation Respiratory minute volume (VE) = Volume of air moved per minute © 2018 Pearson Education, Inc.  Because the respiratory minute volume is determined by multiplying respiratory rate and tidal volume, altering either factor will change the respiratory minute volume © 2018 Pearson Education, Inc.  Module 21.11: Variations in ventilation Alveolar ventilation (VA) = amount of air reaching alveoli/minute  Some air never reaches alveoli; remains in conducting portion of lungs (= anatomic dead space—VD) At rest, averages ~150 mL © 2018 Pearson Education, Inc.  Module 21.11: Variations in ventilation Alveolar ventilation (continued)  Calculated as breaths per minute multiplied by volume of air in the alveoli Volume of air in the alveoli is tidal volume (VT) minus anatomic dead space (VD) VA = f × (VT – VD) When demand for oxygen increases, both tidal volume and respiratory rate must be increased © 2018 Pearson Education, Inc.  Module 21.11 Review A. Define respiratory rate. B. How does the respiratory minute volume differ from alveolar ventilation? C. Which ventilates alveoli more effectively: slow, deep breaths or rapid, shallow breaths? Explain why. Learning Outcome: Explain how respiratory rate and tidal volume affect pulmonary and alveolar ventilation. © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion depends on the partial pressures and solubilities of gases Gas laws—principles that govern the movement and diffusion of gas molecules  Boyle’s law determines direction of air movement during pulmonary ventilation © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion Gas laws (continued)  The atmosphere is a mixture of gases Total atmospheric pressure at sea level is 760 mm Hg  Partial pressure (P) = pressure exerted by single gas in a mixture  Dalton’s law: All the partial pressures of gases added together equal the total pressure exerted by the gas mixture © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion Gas laws (continued)  Gas mixture inside respiratory tract varies by location Inhaled air gets moistened and warmed In alveoli, it mixes with air remaining from previous breath Exhaled air mixes with air in anatomic dead space  As gas mixture varies, so do the partial pressures of its component gases © 2018 Pearson Education, Inc.  Partial pressures of gases varies by location during pulmonary ventilation © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion Gas laws (continued)  Henry’s law: At a given temperature, the amount of a particular gas in solution is directly proportional to the partial pressure of that gas © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion External respiration  Blood arriving in pulmonary arteries has lower PO2 and higher PCO2 than in alveolar air  Diffusion between alveolar mixture and pulmonary capillaries: Increases blood PO2 (oxygen enters blood) Decreases PCO2 (carbon dioxide leaves blood) © 2018 Pearson Education, Inc.  Module 21.12: Gas diffusion Internal respiration  PO2 of blood leaving lungs in pulmonary veins drops slightly when it mixes with blood from capillaries around conducting passageways; still higher than PO2 of interstitial fluid  Oxygen diffuses to interstitial fluid  PCO2 higher in tissues/interstitial fluid than in blood  Carbon dioxide diffuses from tissues into blood © 2018 Pearson Education, Inc.  Module 21.12 Review A. Define Dalton’s law. B. What is the significance of Henry’s law to the process of respiration? C. Explain the decrease in PO2 from the pulmonary venules to the blood arriving in the peripheral capillaries of the systemic circuit. Learning Outcome: Summarize the physical principles governing the diffusion of gases into and out of the blood. © 2018 Pearson Education, Inc.  Module 21.13: Almost all the oxygen in blood is transported bound to hemoglobin within red blood cells Oxygen transport in blood  Each 100 mL of blood leaving alveoli carries ~20 mL oxygen Only ~0.3 mL (1.5 percent) is dissolved in the plasma Remaining 19.7 mL (98.5 percent) is bound to iron ions in heme units of hemoglobin (Hb) © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood Oxygen transport in blood (continued)  Each hemoglobin molecule is made of four globular proteins, each with one heme unit Thus, each hemoglobin molecule can reversibly bind up to four molecules of oxygen; forms oxyhemoglobin (HbO2) Carbon monoxide (CO) is dangerous because it also bind to heme units, making them unavailable for O2 transport © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood Hemoglobin saturation  Percentage of heme units containing bound oxygen at any moment  Oxygen-hemoglobin saturation curve is a graph showing hemoglobin saturation at different partial pressures of oxygen Shape reflects hemoglobin’s increased affinity for oxygen with each oxygen molecule bound – Increases steeply until it plateaus near saturation – Hemoglobin is > 90 percent saturated with oxygen when PO2 is above 60 mm Hg © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood Oxygen-hemoglobin saturation curve (continued)  Hemoglobin in blood entering systemic circuit is ~97 percent saturated PO2 is 95 mm Hg  Hemoglobin in blood leaving body tissues is ~75 percent saturated PO2 is 40 mm Hg Substantial oxygen reserves are present even in venous blood  Hemoglobin in blood in active muscle is only ~20 percent saturated Large amounts of oxygen being released to tissue PO2 is only ~15–20 mm Hg © 2018 Pearson Education, Inc.  The oxygen-hemoglobin saturation curve © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood Blood pH directly affects hemoglobin saturation (Bohr effect)  pH decreases: saturation curve shifts to the right (CO2 accumulation drops pH in active tissues)  pH increases: saturation curve shifts to the left © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood Temperature also affects hemoglobin saturation  Higher temperature leads Hb to release oxygen more readily  Especially important in active tissues (generate heat) © 2018 Pearson Education, Inc.  Module 21.13: Gas transport in blood RBCs lack mitochondria—make ATP only through glycolysis  Same metabolic pathways produce 2,3-bisphosphoglycerate (BPG) The higher the BPG, the more oxygen will be released by Hb molecules BPG production declines as RBCs age – If BPG drops very low, hemoglobin will not release oxygen – Limits storage time for whole blood © 2018 Pearson Education, Inc.  Module 21.13 Review A. Define oxyhemoglobin. B. During exercise, hemoglobin releases more oxygen to active skeletal muscles than it does when those muscles are at rest. Why? C. Explain the relationship among BPG, oxygen, and hemoglobin. Learning Outcome: Discuss the structure and function of hemoglobin, explain the oxygen- hemoglobin saturation curve, and describe the role of 2,3-bisphosphoglycerate. © 2018 Pearson Education, Inc.  Module 21.14: Carbon dioxide is transported three ways in the bloodstream Carbon dioxide transport in blood  Carbon dioxide is generated by aerobic metabolism in peripheral tissues In bloodstream, CO2 is transported in three ways 1. Dissolved in plasma (~7 percent—limited solubility in plasma) 2. Bound to hemoglobin in RBCs (~23 percent) Reversibly attached to exposed amino groups Resulting compound is carbaminohemoglobin (HbCO2) 3. Converted to bicarbonate ion, HCO3− (~70 percent) © 2018 Pearson Education, Inc.  Module 21.14: Carbon dioxide transport Conversion of CO2 to carbonic acid (H2CO3)  Most carbon dioxide entering blood (~70 percent) converts carbonic acid  Reversible reaction catalyzed by carbonic anhydrase CO2 + H2O → H2CO3  Carbonic acid dissociates into bicarbonate and hydrogen ions H2CO3 ↔ HCO3– + H+  Hydrogen ion (H+) binds to Hb, forming HbH+ Hb molecules function as pH buffers © 2018 Pearson Education, Inc.  Module 21.14: Carbon dioxide transport Conversion of CO2 to carbonic acid (H2CO3) (continued)  Bicarbonate ions (HCO3–) exchanged (leave cell) for an extracellular chloride ion (Cl–) Process called chloride shift © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Carbon dioxide transport in the blood © 2018 Pearson Education, Inc.  Module 21.14: Carbon dioxide transport Respiratory gas equilibrium  PO2 and PCO2 are stable in the alveoli and tissues  Equilibrium disrupted when tissue oxygen demand increases Respiratory rate and tidal volume must increase Without that increase, alveolar PO2 levels decrease, and alveolar, blood, and tissue PCO2 levels increase – Can lead to hypoxia and dangerous drop in pH © 2018 Pearson Education, Inc.  Gas exchange at the alveoli (external respiration) © 2018 Pearson Education, Inc.  Gas exchange with peripheral tissues (internal respiration) © 2018 Pearson Education, Inc.  Gas exchange and transport during one respiratory cycle © 2018 Pearson Education, Inc.  BioFlix: Gas Exchange © 2018 Pearson Education, Inc.  Module 21.14: Review A. Identify three ways that carbon dioxide is transported in the bloodstream. B. Describe the forces that drive oxygen and carbon dioxide transport between the blood and peripheral tissues. C. How would blockage of the trachea affect blood pH? Learning Outcome: Describe how carbon dioxide is transported in the blood, and explain how oxygen is picked up, transported, and released into the bloodstream. © 2018 Pearson Education, Inc.  Module 21.15: Clinical Module: Pulmonary disease can affect both lung elasticity and airflow Compliance of the lungs  Indication of how easily the lungs expand  Influenced by internal lung structures (elasticity and resilience) and flexibility of chest wall  Determined by monitoring intrapulmonary pressure at different lung volumes © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Resistance of the lungs  Indicates force required to inflate/deflate lungs  Muscular activity of pulmonary ventilation accounts for 3–5 percent of resting energy demand © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Resistance (continued) Increased resistance means:  More force required to breathe  Increased energy demand for ventilation © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Chronic obstructive pulmonary disease (COPD)  General term for progressive disorder of the airways that restricts airflow and reduces alveolar ventilation  Three examples of COPD 1. Asthma (asthmatic bronchitis) 2. Chronic bronchitis 3. Emphysema © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Asthma (asthmatic bronchitis)  Term used when symptoms are acute and intermittent  Characterized by conducting passageways that are extremely sensitive to irritation  Airways respond by constricting smooth muscles along bronchial tree, edema/swelling of mucosa, increased mucus  Breathing difficult; resistance markedly increased  Triggers include allergies, toxins, exercise © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Chronic bronchitis  Long-term inflammation and swelling of bronchial lining; leads to overproduction of mucus  Frequent cough, lots of sputum can clog airways, increasing resistance, reduced efficiency  Cigarette smoking most common cause Also other environmental irritants  Chronic bacterial infections can damage lungs  Blue bloaters—term for people with cyanosis due to this disorder © 2018 Pearson Education, Inc.  Module 21.15: Pulmonary disease Emphysema  Chronic, progressive condition  Alveoli gradually expand/ merge with adjacent alveoli  Loss of elastic tissues increases compliance  Loss of respiratory surface area restricts oxygen absorption (shortness of breath, intolerance of physical exertion  Pink puffers—term for people with emphysema— heavy breathing with pink coloration © 2018 Pearson Education, Inc.  Module 21.15 Review A. Define compliance and resistance. B. Identify three chronic obstructive pulmonary diseases (COPDs). C. Compare chronic bronchitis with emphysema. Learning Outcome: Explain how pulmonary disease affects compliance and resistance. © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms involve interacting centers in the brainstem  Control involves multiple levels of regulation  Respiratory rate/rhythm set by network of respiratory centers  Most regulation occurs out of conscious control © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 1: Respiratory rhythmicity centers  Most basic control  Pacemaker cells in medulla oblongata generate cycles of contractions in diaphragm  Paired respiratory rhythmicity centers establish pace of respiration by adjusting pacemaker cells and coordinating other respiratory muscles  Each center subdivided into two groups 1. Dorsal respiratory group (DRG) 2. Ventral respiratory group (VRG) © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 1: Respiratory rhythmicity centers (continued)  Dorsal respiratory group varies response through input from: Chemoreceptors detecting O2, Co2, and pH levels in blood/CSF Baroreceptors—stretch receptors; monitor stretch of lung wall Mainly concerned with inspiration Inspiratory center of DRG controls lower motor neurons to primary inspiratory muscles (external intercostals, diaphragm) © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 1: Respiratory rhythmicity centers (continued)  Ventral respiratory group (VRG) Mainly associated with expiration Functions only when breathing demands increase and accessory respiratory muscles are involved  Pre-Bӧtzinger complex—in medulla Essential to all forms of breathing but poorly understood © 2018 Pearson Education, Inc.  Level 1 of Respiratory Control—Respiratory Rhythmicity Centers © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 2: Apneustic and pneumotaxic centers  Paired nuclei in pons  Adjust the output of the respiratory rhythmicity centers Apneustic centers  Promote inhalation by stimulating DRG  Degree of stimulation adjusted based on sensory information from the vagus nerve about lung inflation © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 2: Apneustic and pneumotaxic centers (continued) Pneumotaxic centers  Inhibit apneustic centers  Promote passive or active exhalation  Increased pneumotaxic output shortens inhalation duration (= faster respiratory rate)  Decreased output slows pace and increases depth of respiration © 2018 Pearson Education, Inc.  Level 2 of Respiratory Control—Pneumotaxic and Apneustic Centers © 2018 Pearson Education, Inc.  Module 21.16: Respiratory control mechanisms Level 3: Higher centers  Located in hypothalamus, limbic system, and cerebral cortex  Can alter activity of pneumotaxic centers Normal breathing can occur without higher input © 2018 Pearson Education, Inc.  Level 3 of Respiratory Control—Higher Centers © 2018 Pearson Education, Inc.  Events during quiet breathing © 2018 Pearson Education, Inc.  Events during quiet breathing © 2018 Pearson Education, Inc.  Events during quiet breathing © 2018 Pearson Education, Inc.  Events during quiet breathing © 2018 Pearson Education, Inc.  Events during forced breathing © 2018 Pearson Education, Inc.  Events during forced breathing © 2018 Pearson Education, Inc.  Events during forced breathing © 2018 Pearson Education, Inc.  Events during forced breathing © 2018 Pearson Education, Inc. © 2018 Pearson Education, Inc.  Module 21.16 Review A. Name the paired central nervous system nuclei that adjust the pace of respiration. B. Which brainstem centers generate the respiratory pace? C. Which chemical factors in blood or cerebrospinal fluid stimulate the respiratory centers? Learning Outcome: Describe the brainstem structures that influence the control of respiration. © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes provide rapid automatic adjustments in pulmonary ventilation Chemoreceptor reflexes  Under normal conditions, PCO2 is the most important factor influencing respiration Rise of only 10 percent in arterial PCO2 doubles respiratory rate PO2 levels have to drop below 60 mm Hg before triggering respiratory centers © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes Hypercapnia (increased arterial PCO2)  Most commonly caused by hypoventilation (insufficient respiratory activity to meet oxygen demands)  Increase in PCO2 stimulates chemoreceptors  Body responds by increasing respiratory rate © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes Hypocapnia (decreased arterial PCO2)  Most commonly caused by hyperventilation  In response to low PCO2, body decreases respiratory rate  Swimmers sometimes hyperventilate to extend underwater time Potentially dangerous—if PCO2 levels get too low, person can lose consciousness from oxygen starvation = shallow water blackout © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes Baroreceptor reflexes  Baroreceptors in carotid and aortic sinuses monitored by sensory neurons in glossopharyngeal (IX) and vagus (X) nerves  Sensory information relayed to respiratory centers If arterial BP drops below normal, respiratory centers stimulated, increase respiratory minute volume If arterial BP rises above normal, respiratory centers inhibited, decrease respiratory minute volume © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes Inflation/deflation reflexes  Activated by stretch receptors in lungs during forced breathing (tidal volume ≥ 1000 mL)  Sensory information distributed to apneustic centers and VRG  Inflation reflex prevents overexpansion of lungs  Deflation reflex inhibits expiratory centers; stimulates inspiratory centers when lungs are deflating © 2018 Pearson Education, Inc.  The inflation reflex prevents overexpansion of the lungs during forced breathing © 2018 Pearson Education, Inc.  The deflation reflex inhibits the expiratory centers and stimulates the inspiratory centers when the lungs are deflating © 2018 Pearson Education, Inc.  Module 21.17: Respiratory reflexes Protective reflexes  Occur when exposed to irritants Include sneezing and coughing Both involve apnea (period in which breathing has stopped) followed by forceful expulsion of air to remove irritant © 2018 Pearson Education, Inc.  Module 21.17: Review A. Are chemoreceptors more sensitive to blood CO2 levels or blood O2 levels? B. Define hypercapnia and hypocapnia. C. Johnny is angry, so he tells his mom that he will hold his breath until he turns blue and dies. Explain whether this will likely happen. Learning Outcome: Identify and discuss reflex respiratory activity in pulmonary ventilation. © 2018 Pearson Education, Inc.  Module 21.18: Respiratory function decreases with age; smoking makes matters worse Aging and respiratory function All aspects of respiratory function decrease with age  As elastic tissue deteriorates, vital capacity decreases  Arthritis stiffens rib joints, reducing compliance and maximum respiratory minute volume © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Some degree of emphysema is normal for people over age 50  Extent varies widely with exposure to cigarette smoke and other irritants  Respiratory function declines more with more years of smoking © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Lung cancer—aggressive class of malignancies  Epithelial cells in conducting passages, mucous glands, alveoli  Signs/symptoms often not present until tumors restrict airflow or compress adjacent structures Chest pain, shortness of breath, cough/wheeze, weight loss  Causes more deaths per year than any other type of cancer  85–90 percent of lung cancer cases are direct result of cigarette smoking © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Effects of smoking  Cigarette smoke contains several carcinogens (cancer-causing agents)  Mucus and cilia in normal respiratory epithelium clean inhaled air  Irritants/carcinogens in smoke cause progressive series of changes in the epithelium © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Effects of smoking  Dysplasia (reversible) Cells damaged, and functional characteristics change Cilia damaged and paralyzed—causes local buildup of mucus Epithelium becomes less effective at protecting deeper, delicate parts of respiratory tract © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Effects of smoking (continued)  Metaplasia (reversible) Tissue changes structure Stressed respiratory surface converts to stratified epithelium – Protects underlying layers but not deeper parts of tract – May be reversed if stimulus is removed before further damage © 2018 Pearson Education, Inc.  Module 21.18: Effects of aging and smoking Effects of smoking (continued)  Neoplasia and anaplasia (irreversible) Neoplasia—Growth of abnormal cells forms a cancerous tumor (neoplasm) Anaplasia—most dangerous stage – Cells become malignant and metastasize to other parts of body © 2018 Pearson Education, Inc.  The progressive effects of smoking on the lungs © 2018 Pearson Education, Inc.  Module 21.18 Review A. Name several age-related factors that affect the respiratory system. B. Describe lung cancer. C. Compare dysplasia, metaplasia, neoplasia, and anaplasia. Learning Outcome: Describe age-related changes to, and the effects of cigarette smoking on, the respiratory system. © 2018 Pearson Education, Inc.