Chapter 22 The Respiratory System 22 1 Ch

Chapter 22— The Respiratory System 22 -1

Ch. 22 (Respiratory Sys. ) Study Guide 1. Critically read Chapter 22 pp. 864 -886 right before 22. 3 “Gas Exchange and Transport” section 2. Comprehend Terminology (those in bold) 3. Study-- Figure questions, Think About It questions, and Before You Go On (sectionending) questions 4. Do end-of-the-chapter questions: – Testing Your Recall— 1 -5, 7, 10, 11 -18 – True or False– 1, 2, 4 -6, 8 – Testing Your Comprehension– 1, 4, 5 2

Breathe/Breath (1 or 2) Fear less, hope more; Whine less, breathe more; Talk less, say more; Hate less, love more; And all good things are yours. --Swedish proverb 22 -3

Breathe/Breath (2 of 2) Every day brings a chance for you to draw in a breath, kick off your shoes, and dance. --Oprah Winfrey 22 -4

§ I. Anatomical Consideration Self-Check Question: As we breathe in, what respiratory organs, in order, does air pass through? Answer: Nose (mouth). . . Fig. 22. 1 22 -5

1 § Organs of Respiratory System 2 3 4 5 6 22 -6

General Aspects 1. Airflow in lungs – bronchioles alveoli 2. Conducting & Rspiratory (C/R) divisions-– (C) passages ONLY for airflow, nostrils to bronchioles – (R) distal gas-exchange regions and ____ 3. Upper/lower (U/L) respiratory tracts – (U) organs in head and neck, nose through larynx – (L) organs of trachea through lungs 22 -7

§ 1. Nose • Bony and cartilaginous; supported by: – superior half: nasal bones medially and maxillae laterally – inferior half: lateral and alar cartilages – ala nasi: flared portion shaped by alar cartilages and dense CT; forms lateral wall of each nostril – Fig. 22. 2 a+b 22 -8

Conn. tissues shape the nose (Ala nasi) 22 -9

External Anatomy of Nasal Region 22 -10

Nasal Cavity (1) 1. Extends from nostrils to posterior nares 2. Vestibule: dilated chamber inside ala nasi (just inside the nostril) – stratified squamous epithelium and vibrissae (guard hairs) 3. Nasal septum divides cavity into right and left chambers called nasal fossae – Makes up of = Perpendicular plate of ethmoid bone +. . . 22 -11

Nasal Cavity (2) - Conchae and Meatuses 1. Superior, middle and inferior nasal conchae – 3 folds of tissue on lateral wall of nasal fossa – mucous membranes lines the cavity 2. Meatuses: – narrow air passages beneath each conchae – narrowness and turbulence ensures most air contact the mucous membrane. Fig. 22. 3 22 -12

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Skull-- 2 3 1 Figure 8. 4 b 4 5 6 8 10 11 7 9

Palatine bones

Functions of the nose • Nose (mouth)—air enters the body through here Functions— • Warm and moisten air • Produce nasal mucus– how much each day? By epi. cells • Cilia– push particles toward the throat 22 -16

§ 2. Pharynx (throat) Functions— • Common entryway of. . . • Food and air diverge into two separate branches • Air which organ next? • Food which organ next? Which passage way (air or food) is at the anterior? Figure 22. 3 b+c 22 -17

Lower respiratory tract 22 -18

Three Regions of Pharynx Hyoid bone Cricoid cartilage 22 -19

§ 2. Pharynx (continued) • Nasopharynx (pseudostratified epithelium) – posterior to choanae, dorsal to soft palate – receives auditory tubes; houses _____ tonsil – 90 downward turn; traps large particles (>10 m) • Oropharynx (stratified squamous epithelium) – space between soft palate and root of tongue, inferiorly as far as hyoid bone, contains palatine and lingual tonsils • Laryngopharynx (stratified squamous epi. ) – hyoid bone to level of cricoid cartilage 22 -20

§ 3. Larynx (Voice box) – Anatomy—anterior protrusion called ? – Functions— • Air passageway with cilia • Epiglottis– superior opening of larynx • Voice production by ______ • Laryngitis—Inflammation of the vocal cords; symptoms? Three major causes? 22 -21

Larynx • Glottis – vocal cords and opening between them • Epiglottis – flap of tissue that guards glottis, directs food and drink to esophagus • Infant larynx; epiglottis touches soft palate – higher in throat, forms a continuous airway from nasal cavity to the larynx that allows breathing while swallowing – by age 2, more muscular tongue, forces larynx down to lower position 22 -22

Nine Cartilages of Larynx The superior three (large): 1. Epiglottic cartilage (1)- most superior 2. Thyroid cartilage (1)– largest; laryngeal prominence is the Adam’s apple 3. Cricoid cartilage (1)- connects larynx to trachea • Fig. 22. 4 22 -23

Views of Larynx 1 2 4 5 -6 3 22 -24

Nine Cartilages of Larynx The other 3 small pairs of cartilages: 4. Arytenoid cartilages (2) - posterior to thyroid cartilage 5. Corniculate cartilages (2) - attached to arytenoid cartilages like a pair of little horns The above two pairs of cartilages function in speech 6. Cuneiform cartilages (2) - support soft tissue between arytenoids and epiglottis 22 -25

Walls of Larynx • Interior wall has 2 muscular folds on each side, from thyroid to arytenoid cartilages – Vestibular folds (superior pair) and vocal cords/folds (inferior) (produce sound) • Intrinsic muscles (deep)- rotate corniculate and arytenoid cartilages (Fig. 22. 6) – adducts (tightens: high pitch sound) or abducts (loosens: low pitch sound) vocal cords • Extrinsic muscles (superficial)- connect larynx to hyoid bone, elevate larynx during swallowing 22 -26

High pitch low pitch 22 -27

§ 4. Trachea (windpipe) Anatomy/Histology: Beginning of lower respiratory tract (Fig. 22. 7 a-c +x) 1. Rigid tube 5 in. long and 1 in. diameter, anterior/posterior (? ) to the esophagus 2. Supported by 16 to 20 C-shaped rings; openings facing anterior/posterior (? ) • The lowermost cartilage called ____ 3. A smooth m. (trachealis) spans opening in rings, adjusts airflow; facing (ant. /post. ? ) 4. (Histology) Larynx and trachea lined with ciliated pseudostratified columnar epi. which functions as mucociliary escalator 22 -28

Larynx Trachea Carina See next three slides 22 -29

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Ciliated Pseudostratified Epi. 22 -31

Mucosa 22 -32

ID structures: Practice at home A B C D E 22 -33

§ 4. Trachea (continued) Functions: – Air passageway – Warm and moisten air – Remove particles & debris Clinical applications: – Trachea obstruction and Heimlich Maneuver – Tracheostomy (Insight 22. 1) when the obstruction is superior to the level of the larynx; pitfall? 22 -34

§ 5. Bronchi (supported by cartilages) A. Primary bronchi (2); with C-shaped rings – from trachea; after 2 -3 cm enter hilum of lungs – right bronchus slightly wider and more vertical B. Secondary (lobar) bronchi (2 L. lung+ 3 R. lung); one secondary bronchus for each lobe of lung; cartilage plates C. Tertiary (segmental) bronchi (8 L. lung + 10 R. lung); cartilage plates – bronchopulmonary segment: portion of lung supplied by each tertiary bronchus 22 -35 Fig. 22. 7

All bronchi are supported by cartilages 22 -36

§ 6. Bronchioles (lack cartilage; 1 mm or less in diameter; ciliated simple columnar to ciliated simple cuboidal epi. ) A. Each divides into 50 - 80 terminal bronchioles • Mostly nonciliated simple cuboidal; end of conducting division B. Each terminal bronchiole branches into respiratory bronchioles (respiratory div. now); smallest ones are nonciliated epi. C. Each divides into 2 -10 alveolar ducts (nonciliated simple squamous epi. ); end in alveolar sacs 22 -37 • Fig. 22. 11

§ Bronchial tree Def. --Highly branched system of air tubes from the primary bronchi to about 65, 000 terminal bronchioles Resemble inverted trees Fig. 22. 0 + X 22 -38

Right lung; 10 segments CO 22 Each bronchopulmonary segment by a different color of resin Left lung; 8 segments 22 -39

Right lung; 10 bronchopulmonary segments Left lung; 8 bronchopulmonary segments 22 -40

§ 7. Lungs (Fig. 22. 9 a + b) – Concave base and blunt apex – Costal surface-– Concave mediastinal surface— – The hilum (hilus)– slits/depression where bronchi, blood vessels, nerves entering/leaving – The right lung– shorter; the left lung– narrower, with cardiac impression – L– 2 lobes separated by a fissure – R– 3 lobes separated by two fissures 22 -41

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§ 8. Alveoli meaning hollow 1. Def. – tiny air sacs where. . . 2. Anatomy/physiology— • Each alveolus– single layer of epithelium surrounded by __________ • Numerous alveoli (150 million) in each lung Figure 22. 12 22 -44

Alveolar Blood Supply 22 -45

§ Alveoli—Pore of Kohn • Location? • Function? • Analogy— Fig. x 22 -46

1. Terminal bronchiole A. Branch of pulmonary artery Smooth muscle C. Branch of pulmonary vein 2. Respiratory Bronchiole (beginning of respiratory division) 3. Alveolus Pores of Kohn B. Pulmonary capillaries Alveolar sac 22 -47

§ Alveoli—Three types of cells A. Squamous (Type I) alveolar cells— • • • Location? Function--Gas exchange through these sites; What type of epi. ? Respiratory membrane– 0. 5 micrometer; the barrier between alveolar air and _____ B. Great (Type II) alveolar cells— • • Location? Embed within alveolar walls Functions— secretes surfactant & repairs Figure 22. 12 22 -48

Fluid lining With surfactant B. Great alveolar cell Pulmonary capillary A. Squamous alveolar cell C. Alveolar macrophage Alveolus O 2 Respiratory mem. RBC 22 -49

§ Alveoli—Three types of cells C. Alveolar macrophages (dust cells)— • Most numerous of all cells in the lung • Large tissue-bound phagocytes • Location– within the alveolar lumen • Function-- Phagocytosis 22 -50

Practice at home D A Identify A, B, C, and D. B. C Fig. 22. 11 What is respiratory membrane? b and c Respiratory mem. 22 -51

Questions (muddiest points)? 22 -52

§ II. Pulmonary Ventilation 1. Respiratory cycle– One complete cycle of inspiration and expiration – Breathing (pulmonary ventilation) – repeated cycles above 2. Quiet respiration vs. forced respiration – 3. Basic requirement of respiration: – Flow of air in and out of lung requires a _______ between air pressure within lungs and outside body; why? (next slide) 22 -53

§ Breathing- mechanical steps 1. Why flow of air into and out of the lungs during the breathing? 2. A rule of thumb— • • PV = K (Boyle’s law) with Temp. is constant For example, during inspiration: lung volume increases lung pressure decreases therefore, air flow (from where to where? ___________) Figure x (Boyle’s Law explained) 22 -54

Each container Figure with the same 13. 10 number of gas molecules Piston Page 467 Piston Pressure gauge A. Volume = 1/2 Pressure = 2 B. Volume = 1 Pressure = 1 C. Volume = 2 Pressure = 1/2 PV = K 22 -55

§ Breathing- mechanical steps 3. Mechanism of Inspiration (resting)— A. Diaphragm contracts and move ______? B. External intercostals muscles contract the ribs move _____? C. Chest volume _____? D. Air pressure is _____? (Boyle’s law) E. Air flows inward 4. Deeper Inspiration— A. Neck muscles (among others) are also involved 5 Figures 22 -56

Diaphragm A 2 -dimentional figure 22 -57

2. Contraction of external intercostal muscles increases side-to-side dimension (x) increases front-to-back Dimension (y) Quiet Inspiration 1. Contraction of diaphragm increases vertical dimension of (z) A 3 -dimentional figure 22 -58

Equilibrated; no net movement of air 760 mm. Hg Before inspiration Preinspiratory size of thorax 760 mm. Hg Preinspiratory size of lungs 22 -59

760 mm Hg During inspiration Size of thorax on contraction of inspiratory muscles 757 -759 mm Hg (from 760) Size of lungs as they are stretched to fill the expanded thorax; pressure Demonstration —lung model 22 -60

Muscles of deeper inspiration 1. Sternocleidomastoid 2. Scalenus Muscles of active/forced expiration Internal intercostal muscles 1. External intercostal muscles 2. Diaphragm Major muscles of inspiration Abdominal muscles 22 -61

§ Breathing- mechanical steps (students practice on this; KEY on next slide) 5. Mechanism of Expiration— A. Diaphragm ____ and becomes ______ B. External intercostal muscles ____ the ribs move ______ C. Chest volume _____? D. Air pressure is _____? (Boyle law) E. Air flows outward 6. Forced expiration: abdominal and internal intercostal muscles are involved Figures 22. 13 22 -62

Relaxation of external intercostal muscles Contraction of internal intercostal muscles flattens ribs and sternum, further reducing side-to-side and front-to-back dimensions of thoracic cavity A review slide on expiration Contraction of abdominal muscles Relaxation of diaphragm Passive expiration Return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size Position of relaxed abdominal muscles Contractions of abdominal muscles cause diaphragm to be pushed upward, further reducing vertical dimension of thoracic cavity Active expiration 22 -63

760 mm Hg During expiration Size of thorax on relaxation of inspiratory muscles 761 mm Hg (from 760) Size of lungs as they recoil 22 -64

§ Summary of respiratory muscles (This slide for review with Fig. x next) 1. Diaphragm (dome shaped) – contraction flattens diaphragm 2. External intercostals – increases X&Y diameter; stiffen thoracic cage 3. Scalenes - hold first 2 pair of ribs stationary 4. Pectoralis minor, sternocleidomastoid and erector spinae muscles – used in forced inspiration 5. Abdominals, internal intercostals, and latissimus dorsi – forced expiration (to sing, cough, sneeze) – Valsalva maneuver– raise abdominal pressure. . . 22 -65

Forced Inspiration Forced Expiration Quiet Inspiration 22 -66

§ III. Neural Control of Breathing 22 -67

§ Neural Control of Breathing (1) 1. Breathing depends on repetitive stimuli from the brain—controlled at two levels (A & B below): A. Neurons in medulla oblongata and pons control unconscious breathing • Ondine’s curse – brainstem damage • Causes– Poliomyelitis etc. • Symptoms– disabled automatic respiratory functions • Cure-B. Voluntary control provided by motor cortex is cerebral and consciously controlled 22 -68

§ Neural Control of Breathing (2) 2. Unconscious breathing: A. Inspiratory neurons: fire during inspiration B. Expiratory neurons: fire during forced expiration C. Fibers of phrenic nerve go to diaphragm; intercostal nerves to intercostal muscles 22 -69

§ Three Respiratory Control Centers in the brainstem (Fig. 14. 4) 1. Ventral respiratory group (VRG) in medulla • Primary generator of respiratory rhythm • Having both inspiratory and expiratory neurons, taking turns to fire spinal integrating centers 2. Dorsal respiratory group (DRG) in medulla • An integrating center– inputs from. . . (Fig. 22. 4) • Output to the VRG modifying respiratory rhythm 3. Pontine respiratory group (PRG) in pons • Modifies the rhythm of the VRG • Making each breath shorter/shallower OR longer/ deeper– during sleep, exercise, etc. 22 -70

Anterior 1. from higher brain centers Pons 3. Central Chemoreceptors 4. CN IX and X 2. PRG DRG VRG Medulla Spinal integrating centers 22 -72

§ Input to the respiratory centers 1. Central chemoreceptors (in medulla) • primarily monitor p. H (and CO 2) of CSF 2. Peripheral chemoreceptors (Fig. 22. 15) – Monitor p. H, O 2 and CO 2 and fibers synapse to the DRG 3. Stretch receptors (bronchi and bronchioles) – Excessive inflation triggers inflation reflex and stops inspiration 4. Irritant receptors (epithelial cells of the airway) – Respond to particles and trigger coughing etc. 22 -73

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§ Voluntary Control of breathing • Neural pathways – motor cortex of frontal lobe of cerebrum sends impulses down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem • Limitations on voluntary control – blood CO 2 and O 2 limits cause automatic respiration overrides one’s will • Voluntary control is important in singing, speaking, breath-holding 22 -75

Check Point Questions Q--Where exactly are the medulla oblongata and the pons located, respectively? Answer: medulla oblongata is the most caudal part of the brainstem (stalklike lower portion of the brain), immediately superior to the spinal cord • The pons is a part of the brainstem located immediately superior to the medulla oblongata and ventral to the cerebellum 22 -76

Q-- Is it possible that temperamental children may hold their breath until they die? § Next section--IV. Pressure, Resistance, and Airflow 22 -77

§ Pressure and Airflow (1) Introduction– (Mostly we have talked about) 1. Atmospheric (barometric) pressure-– 1 atmosphere (atm) = 760 mm. Hg 2. Intrapulmonary pressure and lung volume – pressure is inversely proportional to volume • for a given amount of gas, as volume , pressure and as volume , pressure 3. Pressure gradients matters to airflow-– difference between atmospheric and intrapulmonary pressure – Airflow (F) = ΔP (pressure gradient) 22 -78

§ Pressure and Airflow (2) During inspiration; how lungs are expanded? 1. Ribs swing upward and outward lungs expand with thoracic cage • intrapulmonary pressure (-3 mm Hg; 3 mm Hg below atmospheric pressure) • 500 ml of air flows into the lungs (tidal volume) 2. Another force expands the lungs– warming of the inhaled air. Inhaled air expands, it helps to inflate the lungs. (Charles’s law) • Charles’s law– volume of given quantity of gas is directly proportional to its absolute temperature 22 -79

§ Pressure and Airflow (3) Recoiling mechanisms during expiration: 1. During quiet breathing, expiration achieved by elasticity of lungs and thoracic cage etc. 2. As volume of thoracic cavity , intrapulmonary pressure (+3 mm Hg) and air is expelled 3. Pulmonary elasticity related disorders: – Atelectasis– The collapse of a lung – Causes– A) Pneumothorax (air in the pleural cavity; see next slide), B) airway obstruction (that part of lung collapses b/c it cannot be reventilated, for example inadequate surfactant, aspirated object etc. 22 -80

§ Pneumothorax • • • Def. —abnormal condition of air entering the pleural sac Causes— (see fig. x) Consequences— transmural pressure gradient no longer exists and. . . Figure x 22 -81

760 Atelectasis (pneumothorax) A 760 B 760 C 760; intrapulmonary pressure 756; intrapleural pressure Collapsed lung A– Parietal pleura; B—pleural cavity (pleural fluid); C– Visceral pleura 22 -82

§ Pulmonary surfactant (1) 1. A potential problem of breathing • • In alveoli—tiny sacs. . . ; why? b/c surface tension of water— Fig. z 2. Solution-- pulmonary surfactant • • • What is it? Phospholipoproteins Where does it from? By what cell type? Functions? 22 -83

Demonstration H 2 O molecules An alveolus 22 -84

§ Pulmonary surfactant (2) 3. (Newborn/Infant) respiratory distress syndrome (IRDS)— A. What is lacking in premature infants? B. What are the problems? • • • When surfactant is produced? Alveoli collapsed completely — Newborn’s muscles-- C. Cure-85

Check Point Questions • What types of cells make up the wall of an alveolus? Function? • What type of cell in the lungs secrete pulmonary surfactant? Function? 22 -86

§ V. Alveolar Ventilation 22 -87

§ Alveolar Ventilation (1) Does all inhaled air enter the alveoli? 1. Dead air (150 ml per breath) – fills conducting division of airway, cannot exchange gases with the blood 2. Where is the dead air? In anatomic dead space: – It exists in conducting division of airway – Normally about _______m. L 3. Physiological (total) dead space – sum of anatomic dead space and any pathological alveolar dead space 22 -88

§ Alveolar ventilation (2) 1. Alveolar ventilation rate (AVR): body’s ability to get oxygen to the tissues per minute – alveolar ventilation rate (AVR) = (Tidal volume - dead space volume) x respiratory rate – AVR = (500 -150 m. L) x 12 breaths/min = 4, 200 m. L/min 89

§ Measurements of Ventilation (1) 1. Spirometer – measures ventilation; specifically respiratory volumes and capacities Fig. x 22 -90

Floating drum Air Recording paper advancing with time Spirogram Water Expired air Inspired air 22 -91

§ Measurements of Ventilation (2) 2. Respiratory volumes: A. Tidal volume (TV) - The air entering or leaving the lungs in a single breath. B. Inspiratory reserve volume (IRV) - The extra air that can be maximally inspired over the typical resting TV. C. Expiratory reserve volume (ERV) - The maximal volume of air that can be actively expired beyond a tidal volume. D. Residual volume (RV) - air remaining in lungs after maximum expiration 92 Fig. 22. 17

a capacity is the sum of more than two volumes 2 1 3 4 22 -93

§ Measurements of Ventilation (3) 3. Respiratory capacities: A. Inspiratory capacity (IC) - The maximum volume of air that can be inspired at the end of a normal quiet expiration. = TV + IRV B. Functional residual capacity (FRC) – Amount of air remaining in the lungs after a normal tidal expiration; = RV + ERV C. Vital capacity (VC) - The maximum volume of air that can be expired following a maximal inspiration. = TV + IRV + ERV D. Total lung capacity (TLC) - maximum amount of 94 air lungs can hold; = VC + RV

ID the following respiratory volumes/capacities D A F G B C H E Work on this figure at home. 22 -95

Check Point Question • If you breathe in as deeply as possible and then exhale as much air as you can, which lung volume or capacity have you demonstrated? 22 -96

§ Lung disorders and spirometry 1. Restrictive disorders– Those having reduce pulmonary compliance, limiting the amount to which the lungs can be inflated • Disorders- black lung disease, tuberculosis • Spirometry- reduced IC, VC, TLC 2. Obstructive disorders (COPD; Chronic Obstructive Pulmonary Disease) – those that interfere with airflow by narrowing or blocking the airway • Disorders– asthma, emphysema etc. • Detection: Forced expiratory volume (FEV)-- % of vital capacity exhaled/time; healthy adult - ______% of VC in 1 sec (Fig. Y) 97

FEV 1. 0 1 sec interval 22 -98