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© 2013 Pearson Education, Inc.
The Respiratory System
• Major function-respiration– Supply body with O2 for cellular respiration;
dispose of CO2, a waste product of cellular respiration
– Its four processes involve both respiratory and circulatory systems
• Also functions in olfaction and speech
© 2013 Pearson Education, Inc.
• Pulmonary ventilation (breathing)-movement of air into and outof lungs
• External respiration-O2 and CO2
exchange between lungs and blood
• Transport-O2 and CO2 in blood
• Internal respiration-O2 and CO2
exchange between systemic bloodvessels and tissues
Respiratorysystem
Circulatorysystem
Processes of Respiration
© 2013 Pearson Education, Inc.
Respiratory System: Functional Anatomy
• Major organs– Nose, nasal cavity, and paranasal sinuses– Pharynx– Larynx– Trachea– Bronchi and their branches– Lungs and alveoli
© 2013 Pearson Education, Inc.
Figure 22.1 The major respiratory organs in relation to surrounding structures.
Nasal cavity
Nostril
Larynx
Trachea
Carina of trachea
Right main (primary) bronchusRightlung
Oral cavity
Pharynx
Left main (primary) bronchus
Left lung
Diaphragm
• Respiratory zone-site of gas exchange – Microscopic structures-respiratory
bronchioles, alveolar ducts, and alveoli
• Conducting zone-conduits to gas exchange sites– Includes all other respiratory structures;
cleanses, warms, humidifies air
• Diaphragm and other respiratory muscles promote ventilation
© 2013 Pearson Education, Inc.
Animation: Rotating face
Functional Anatomy
PLAYPLAY
© 2013 Pearson Education, Inc.
The Nose
• Functions– Provides an airway for respiration– Moistens and warms entering air– Filters and cleans inspired air – Serves as resonating chamber for speech– Houses olfactory receptors
© 2013 Pearson Education, Inc.
The Nose
• Two regions-external nose and nasal cavity
• External nose-root, bridge, dorsum nasi, and apex – Philtrum-shallow vertical groove inferior to
apex– Nostrils (nares)-bounded laterally by alae
© 2013 Pearson Education, Inc.
Figure 22.2a The external nose.
Epicranius,frontal belly
Root andbridge of nose
Dorsum nasi
Ala of nose
Apex of nose
Naris (nostril)
Surface anatomy
© 2013 Pearson Education, Inc.
Figure 22.2b The external nose.
Frontal bone
Nasal bone
Septal cartilage
Maxillary bone(frontal process)
Lateral process ofseptal cartilageMinor alarcartilagesDense fibrousconnective tissueMajor alarcartilages
External skeletal framework
© 2013 Pearson Education, Inc.
The Nose
• Nasal cavity-within and posterior to external nose– Divided by midline nasal septum– Posterior nasal apertures (choanae) open
into nasal pharynx – Roof-ethmoid and sphenoid bones – Floor–hard (bone) and soft palates (muscle)
© 2013 Pearson Education, Inc.
Nasal Cavity
• Nasal vestibule-nasal cavity superior to nostrils – Vibrissae (hairs) filter coarse particles from
inspired air
• Rest of nasal cavity lined with mucous membranes– Olfactory mucosa– Respiratory mucosa
© 2013 Pearson Education, Inc.
Nasal Cavity
• Olfactory mucosa contains olfactory epithelium
• Respiratory mucosa– Pseudostratified ciliated columnar epithelium– Mucous and serous secretions contain
lysozyme and defensins – Cilia move contaminated mucus posteriorly to
throat– Inspired air warmed by plexuses of capillaries
and veins– Sensory nerve endings trigger sneezing
© 2013 Pearson Education, Inc.
Figure 22.3b The upper respiratory tract.
Pharyngeal tonsil
Oropharynx
Cribriform plateof ethmoid bone
Sphenoid sinus
Posterior nasalaperture
Nasopharynx
Opening ofpharyngotympanic tube
Uvula
Palatine tonsilIsthmus of thefauces
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavityNasal conchae(superior, middle and inferior)
Nasal meatuses(superior, middle,and inferior)Nasal vestibule
Nostril
Hard palate
Soft palate
Tongue
Lingual tonsil
Hyoid boneLarynxEpiglottisVestibular foldThyroid cartilageVocal foldCricoid cartilage
Thyroid gland
Illustration
© 2013 Pearson Education, Inc.
Figure 22.3a The upper respiratory tract.
Olfactoryepithelium
Mucosa of pharynx
Tubaltonsil
Pharyngotympanic(auditory) tube
Nasopharynx
Olfactory nerves
Superior nasal concha and superior nasal meatus
Middle nasal concha and middle nasal meatus
Inferior nasal concha and inferior nasal meatus
Hard palate
Soft palate
Uvula
Photograph
© 2013 Pearson Education, Inc.
Nasal Cavity
• Nasal conchae-superior, middle, and inferior– Protrude medially from lateral walls– Increase mucosal area– Enhance air turbulence
• Nasal meatus– Groove inferior to each concha
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Functions of the Nasal Mucosa and Conchae
• During inhalation, conchae and nasal mucosa– Filter, heat, and moisten air
• During exhalation these structures– Reclaim heat and moisture
© 2013 Pearson Education, Inc.
Paranasal Sinuses
• In frontal, sphenoid, ethmoid, and maxillary bones
• Lighten skull; secrete mucus; help to warm and moisten air
© 2013 Pearson Education, Inc.
Homeostatic Imbalance
• Rhinitis– Inflammation of nasal mucosa– Nasal mucosa continuous with mucosa of
respiratory tract spreads from nose throat chest
– Spreads to tear ducts and paranasal sinuses causing
• Blocked sinus passageways air absorbed vacuum sinus headache
© 2013 Pearson Education, Inc.
Pharynx
• Muscular tube from base of skull to C6
– Connects nasal cavity and mouth to larynx and esophagus
– Composed of skeletal muscle
• Three regions– Nasopharynx– Oropharynx– Laryngopharynx
© 2013 Pearson Education, Inc.
Figure 22.3c The upper respiratory tract.
Nasopharynx
Oropharynx
Laryngopharynx
Regions of the pharynx
Pharynx
© 2013 Pearson Education, Inc.
Nasopharynx
• Air passageway posterior to nasal cavity• Lining - pseudostratified columnar
epithelium• Soft palate and uvula close nasopharynx
during swallowing• Pharyngeal tonsil (adenoids) on posterior
wall • Auditory tubes drain and equalize
pressure in middle ear; open into lateral walls
© 2013 Pearson Education, Inc.
Oropharynx
• Passageway for food and air from level of soft palate to epiglottis
• Lining of stratified squamous epithelium
• Isthmus of fauces-opening to oral cavity
• Palatine tonsils-in lateral walls of fauces
• Lingual tonsil-on posterior surface of tongue
© 2013 Pearson Education, Inc.
Laryngopharynx
• Passageway for food and air
• Posterior to upright epiglottis
• Extends to larynx, where continuous with esophagus
• Lined with stratified squamous epithelium
© 2013 Pearson Education, Inc.
Figure 22.3b The upper respiratory tract.
Pharyngeal tonsil
Oropharynx
Cribriform plateof ethmoid bone
Sphenoid sinus
Posterior nasalaperture
Nasopharynx
Opening ofpharyngotympanic tube
Uvula
Palatine tonsilIsthmus of thefauces
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavityNasal conchae(superior, middle and inferior)
Nasal meatuses(superior, middle,and inferior)Nasal vestibule
Nostril
Hard palate
Soft palate
Tongue
Lingual tonsil
Hyoid boneLarynxEpiglottisVestibular foldThyroid cartilageVocal foldCricoid cartilage
Thyroid gland
Illustration
© 2013 Pearson Education, Inc.
Larynx
• Attaches to hyoid bone; opens into laryngopharynx; continuous with trachea
• Functions– Provides patent airway– Routes air and food into proper channels– Voice production
• Houses vocal folds
© 2013 Pearson Education, Inc.
Larynx
• Nine cartilages of larynx– All hyaline cartilage except epiglottis– Thyroid cartilage with laryngeal
prominence (Adam's apple)– Ring-shaped cricoid cartilage– Paired arytenoid, cuneiform, and
corniculate cartilages– Epiglottis-elastic cartilage; covers laryngeal
inlet during swallowing; covered in taste bud-containing mucosa
© 2013 Pearson Education, Inc.
Figure 22.4a The larynx.
Body of hyoid bone
Thyroid cartilage
Laryngeal prominence(Adam’s apple)
Cricothyroid ligament
Cricotracheal ligament
Epiglottis
Thyrohyoidmembrane
Cricoid cartilage
Tracheal cartilages
Anterior superficial view
© 2013 Pearson Education, Inc.
Figure 22.4b The larynx.
Epiglottis
Thyrohyoidmembrane
Cuneiform cartilage
Corniculate cartilage
Arytenoid cartilage
Arytenoid muscles
Cricoid cartilage
Tracheal cartilages
Body of hyoid bone
Thyrohyoid membrane
Fatty pad
Vestibular fold(false vocal cord)
Thyroid cartilage
Vocal fold(true vocal cord)
Cricothyroid ligament
Cricotracheal ligament
Sagittal view; anterior surface to the right
© 2013 Pearson Education, Inc.
Figure 22.4c The larynx.
Epiglottis
Hyoid bone
Thyroidcartilage
Lateralthyrohyoidmembrane
Corniculatecartilage
Arytenoidcartilage
Glottis
Cricoidcartilage
Trachealcartilages
Photograph of cartilaginous frameworkof the larynx, posterior view
© 2013 Pearson Education, Inc.
Figure 22.4d The larynx.
Posterior cricoarytenoid muscle on cricoidcartilage
Trachea
Corniculatecartilage
Laryngealinlet
Epiglottis
Photograph of posterior aspect(d)
© 2013 Pearson Education, Inc.
Larynx
• Vocal ligaments-deep to laryngeal mucosa– Attach arytenoid cartilages to thyroid cartilage– Contain elastic fibers – Form core of vocal folds (true vocal cords)
• Glottis-opening between vocal folds• Folds vibrate to produce sound as air rushes up
from lungs
© 2013 Pearson Education, Inc.
Larynx
• Vestibular folds (false vocal cords)– Superior to vocal folds– No part in sound production– Help to close glottis during swallowing
© 2013 Pearson Education, Inc.
Figure 22.5 Movements of the vocal folds.
Vestibular fold (false vocal cord)
Base of tongue
Epiglottis
Vocal fold (true vocal cord)
Glottis
Inner lining of trachea
Cuneiform cartilage
Corniculate cartilage
Vocal folds in closed position; closed glottis Vocal folds in open position; open glottis
© 2013 Pearson Education, Inc.
Epithelium of Larynx
• Superior portion–stratified squamous epithelium
• Inferior to vocal folds–pseudostratified ciliated columnar epithelium
© 2013 Pearson Education, Inc.
Voice Production
• Speech-intermittent release of expired air while opening and closing glottis
• Pitch determined by length and tension of vocal cords
• Loudness depends upon force of air• Chambers of pharynx, oral, nasal, and sinus
cavities amplify and enhance sound quality • Sound is "shaped" into language by muscles of
pharynx, tongue, soft palate, and lips
© 2013 Pearson Education, Inc.
Larynx
• Vocal folds may act as sphincter to prevent air passage
• Example-Valsalva's maneuver– Glottis closes to prevent exhalation– Abdominal muscles contract– Intra-abdominal pressure rises – Helps to empty rectum or stabilizes trunk
during heavy lifting
© 2013 Pearson Education, Inc.
Trachea
• Windpipe–from larynx into mediastinum
• Wall composed of three layers– Mucosa-ciliated pseudostratified epithelium
with goblet cells – Submucosa-connective tissue with
seromucous glands– Adventitia-outermost layer made of
connective tissue; encases C-shaped rings of hyaline cartilage
© 2013 Pearson Education, Inc.
Trachea
• Trachealis muscle– Connects posterior parts of cartilage rings– Contracts during coughing to expel mucus
• Carina– Spar of cartilage on last, expanded tracheal
cartilage– Point where trachea branches into two main
bronchi
© 2013 Pearson Education, Inc.
Figure 22.6a Tissue composition of the tracheal wall.
Esophagus
Trachealismuscle
Lumen oftrachea
Posterior
Mucosa
Submucosa
Hyaline cartilage
Adventitia
Seromucous glandin submucosa
Anterior
Cross section of the tracheaand esophagus
© 2013 Pearson Education, Inc.
Figure 22.6b Tissue composition of the tracheal wall.
Goblet cell
• Pseudostratified ciliated columnar epithelium
• Lamina propria (connective tissue)
Mucosa
Submucosa
Hyaline cartilage
Seromucous glandIn submucosa
Photomicrograph of the trachealwall (320x)
© 2013 Pearson Education, Inc.
Figure 22.6c Tissue composition of the tracheal wall.
Scanning electron micrograph of cilia in thetrachea (2500x)
© 2013 Pearson Education, Inc.
Bronchi and Subdivisions
• Air passages undergo 23 orders of branching bronchial (respiratory) tree
• From tips of bronchial tree conducting zone structures respiratory zone structures
© 2013 Pearson Education, Inc.
Conducting Zone Structures
• Trachea right and left main (primary) bronchi
• Each main bronchus enters hilum of one lung– Right main bronchus wider, shorter, more
vertical than left
• Each main bronchus branches into lobar (secondary) bronchi (three on right, two on left)– Each lobar bronchus supplies one lobe
© 2013 Pearson Education, Inc.
Conducting Zone Structures
• Each lobar bronchus branches into segmental (tertiary) bronchi– Segmental bronchi divide repeatedly
• Branches become smaller and smaller – Bronchioles-less than 1 mm in diameter– Terminal bronchioles-smallest-less than
0.5 mm diameter
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Figure 22.7 Conducting zone passages.
Superior lobe of right lung
Middle lobeof right lung
Inferior lobeof right lung
Trachea
Superior lobeof left lung
Left main(primary)bronchus
Lobar (secondary)bronchus
Segmental (tertiary)bronchus
Inferior lobeof left lung
© 2013 Pearson Education, Inc.
Conducting Zone Structures
• From bronchi through bronchioles, structural changes occur– Cartilage rings become irregular plates; in
bronchioles elastic fibers replace cartilage– Epithelium changes from pseudostratified
columnar to cuboidal; cilia and goblet cells become sparse
– Relative amount of smooth muscle increases• Allows constriction
© 2013 Pearson Education, Inc.
Respiratory Zone
• Begins as terminal bronchioles respiratory bronchioles alveolar ducts alveolar sacs – Alveolar sacs contain clusters of alveoli
• ~300 million alveoli make up most of lung volume• Sites of gas exchange
© 2013 Pearson Education, Inc.
Figure 22.8a Respiratory zone structures.
Alveolar duct
Respiratory bronchioles
Terminalbronchiole
Alveoli
Alveolar duct
Alveolar sac
© 2013 Pearson Education, Inc.
Figure 22.8b Respiratory zone structures.
Respiratorybronchiole
Alveolarduct
Alveoli
Alveolarsac
Alveolarpores
© 2013 Pearson Education, Inc.
Respiratory Membrane
• Alveolar and capillary walls and their fused basement membranes– ~0.5- m-thick; gas exchange across
membrane by simple diffusion
• Alveolar walls– Single layer of squamous epithelium (type I
alveolar cells)
• Scattered cuboidal type II alveolar cells secrete surfactant and antimicrobial proteins
© 2013 Pearson Education, Inc.
Figure 22.9a Alveoli and the respiratory membrane.
Terminal bronchiole
Respiratory bronchiole
Smoothmuscle
Elasticfibers
Alveolus
Capillaries
Diagrammatic view of capillary-alveoli relationships
© 2013 Pearson Education, Inc.
Figure 22.9b Alveoli and the respiratory membrane.
Scanning electron micrograph of pulmonary capillary casts (70x)
© 2013 Pearson Education, Inc.
Alveoli
• Surrounded by fine elastic fibers and pulmonary capillaries
• Alveolar pores connect adjacent alveoli• Equalize air pressure throughout lung
• Alveolar macrophages keep alveolar surfaces sterile– 2 million dead macrophages/hour carried by
cilia throat swallowed
© 2013 Pearson Education, Inc.
Figure 22.9c Alveoli and the respiratory membrane.
Red bloodcell incapillary
Alveoli(gas-filledair spaces)
Type IIalveolarcell
Type Ialveolarcell
Capillary
MacrophageEndothelial cellnucleus
Respiratorymembrane
AlveolarepitheliumFused basementmembranes ofalveolarepithelium andcapillaryendotheliumCapillaryendothelium
Capillary
Alveolus
Nucleus of type Ialveolar cell
Alveolar pores
Red bloodcell
Alveolus
Detailed anatomy of the respiratory membrane
© 2013 Pearson Education, Inc.
Lungs
• Occupy all thoracic cavity except mediastinum
• Root-site of vascular and bronchial attachment to mediastinum
• Costal surface-anterior, lateral, and posterior surfaces
• Composed primarily of alveoli
• Balance–stroma-elastic connective tissue elasticity
© 2013 Pearson Education, Inc.
Figure 22.10c Anatomical relationships of organs in the thoracic cavity.
Transverse section through the thorax, viewed from above. Lungs, pleuralmembranes, and major organs in the mediastinum are shown.
Posterior
Parietal pleura
Visceral pleura
Pleural cavity
Pericardial membranes
Sternum
Vertebra
Esophagus(in mediastinum)
Root of lungat hilum• Left mainbronchus• Left pulmonaryartery• Left pulmonaryvein
Thoracic wall
Heart (in mediastinum)Anterior mediastinum
Anterior
Left lung
Pulmonary trunk
Right lung
© 2013 Pearson Education, Inc.
Lungs
• Apex-superior tip; deep to clavicle• Base-inferior surface; rests on diaphragm• Hilum-on mediastinal surface; site for
entry/exit of blood vessels, bronchi, lymphatic vessels, and nerves
• Left lung smaller than right– Cardiac notch-concavity for heart– Separated into superior and inferior lobes by
oblique fissure
© 2013 Pearson Education, Inc.
Lungs
• Right lung– Superior, middle, inferior lobes separated by
oblique and horizontal fissures
• Bronchopulmonary segments (10 right, 8–10 left) separated by connective tissue septa– If diseased can be individually removed
• Lobules-smallest subdivisions visible to naked eye; served by bronchioles and their branches
© 2013 Pearson Education, Inc.
Figure 22.10a Anatomical relationships of organs in the thoracic cavity.
TracheaThymus
Apex of lung
Right inferior lobe
Horizontal fissure
Right superior lobe
Oblique fissure
Right middle lobe
Heart(in mediastinum)
Diaphragm
Base of lung
Intercostal muscleRib
Parietal pleuraPleural cavityVisceral pleura
Leftsuperior lobe
Obliquefissure
Left inferiorlobe
Cardiac notch
Anterior view. The lungs flank mediastinal structures laterally.
Lung
© 2013 Pearson Education, Inc.
Figure 22.10b Anatomical relationships of organs in the thoracic cavity.
Apex of lung
Pulmonary artery
Left mainbronchus
Pulmonaryvein
Cardiacimpression
Obliquefissure
Lobules
Photograph of medial view of theleft lung.
Leftsuperior lobe
Obliquefissure
Left inferiorlobe
Hilum of lung
Aorticimpression
© 2013 Pearson Education, Inc.
Figure 22.11 A cast of the bronchial tree.
Right lung Left lung
Left superiorlobe(4 segments)
Left inferiorlobe(5 segments)
Rightinferior lobe(5 segments)
Rightmiddlelobe (2segments)
Rightsuperiorlobe (3segments)
© 2013 Pearson Education, Inc.
Blood Supply
• Pulmonary circulation (low pressure, high volume)– Pulmonary arteries deliver systemic venous
blood to lungs for oxygenation• Branch profusely; feed into pulmonary capillary
networks
– Pulmonary veins carry oxygenated blood from respiratory zones to heart
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Blood Supply
– Lung capillary endothelium contains enzymes that act on substances in blood
• E.g., angiotensin-converting enzyme–activates blood pressure hormone
© 2013 Pearson Education, Inc.
Blood Supply
• Bronchial arteries provide oxygenated blood to lung tissue– Arise from aorta and enter lungs at hilum– Part of systemic circulation (high pressure,
low volume) – Supply all lung tissue except alveoli– Bronchial veins anastomose with pulmonary
veins• Pulmonary veins carry most venous blood back to
heart
© 2013 Pearson Education, Inc.
Pleurae
• Thin, double-layered serosa; divides thoracic cavity into two pleural compartments and mediastinum
• Parietal pleura on thoracic wall, superior face of diaphragm, around heart, between lungs
• Visceral pleura on external lung surface• Pleural fluid fills slitlike pleural cavity
– Provides lubrication and surface tension assists in expansion and recoil
© 2013 Pearson Education, Inc.
Figure 22.10c Anatomical relationships of organs in the thoracic cavity.
Transverse section through the thorax, viewed from above. Lungs, pleuralmembranes, and major organs in the mediastinum are shown.
Posterior
Parietal pleura
Visceral pleura
Pleural cavity
Pericardial membranes
Sternum
Vertebra
Esophagus(in mediastinum)
Root of lungat hilum• Left mainbronchus• Left pulmonaryartery• Left pulmonaryvein
Thoracic wall
Heart (in mediastinum)Anterior mediastinum
Anterior
Left lung
Pulmonary trunk
Right lung
© 2013 Pearson Education, Inc.
Mechanics of Breathing
• Pulmonary ventilation consists of two phases– Inspiration-gases flow into lungs– Expiration-gases exit lungs
© 2013 Pearson Education, Inc.
Pressure Relationships in the Thoracic Cavity
• Atmospheric pressure (Patm)
– Pressure exerted by air surrounding body – 760 mm Hg at sea level = 1 atmosphere
• Respiratory pressures described relative to Patm
– Negative respiratory pressure-less than Patm
– Positive respiratory pressure-greater than Patm
– Zero respiratory pressure = Patm
© 2013 Pearson Education, Inc.
Intrapulmonary Pressure
• Intrapulmonary (intra-alveolar) pressure (Ppul)
– Pressure in alveoli– Fluctuates with breathing
– Always eventually equalizes with Patm
© 2013 Pearson Education, Inc.
Intrapleural Pressure
• Intrapleural pressure (Pip)
– Pressure in pleural cavity– Fluctuates with breathing
– Always a negative pressure (<Patm and <Ppul)
– Fluid level must be minimal• Pumped out by lymphatics
• If accumulates positive Pip pressure lung collapse
© 2013 Pearson Education, Inc.
Intrapleural Pressure
• Negative Pip caused by opposing forces
– Two inward forces promote lung collapse• Elastic recoil of lungs decreases lung size• Surface tension of alveolar fluid reduces alveolar
size
– One outward force tends to enlarge lungs• Elasticity of chest wall pulls thorax outward
© 2013 Pearson Education, Inc.
Pressure Relationships
• If Pip = Ppul or Patm lungs collapse
• (Ppul – Pip) = transpulmonary pressure
– Keeps airways open– Greater transpulmonary pressure larger
lungs
© 2013 Pearson Education, Inc.
Figure 22.12 Intrapulmonary and intrapleural pressure relationships.
Atmospheric pressure (Patm)0 mm Hg (760 mm Hg)
Thoracic wall
Parietal pleura
Visceral pleura
Pleural cavity
Transpulmonarypressure4 mm Hg(the differencebetween 0 mm Hgand −4 mm Hg)
Intrapleuralpressure (Pip)−4 mm Hg(756 mm Hg)
Intrapulmonarypressure (Ppul)0 mm Hg(760 mm Hg)
Diaphragm
Lung
0
– 4
© 2013 Pearson Education, Inc.
Homeostatic Imbalance
• Atelectasis (lung collapse) due to– Plugged bronchioles collapse of alveoli– Pneumothorax-air in pleural cavity
• From either wound in parietal or rupture of visceral pleura
• Treated by removing air with chest tubes; pleurae heal lung reinflates
© 2013 Pearson Education, Inc.
Pulmonary Ventilation
• Inspiration and expiration
• Mechanical processes that depend on volume changes in thoracic cavity– Volume changes pressure changes– Pressure changes gases flow to equalize
pressure
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Boyle's Law
• Relationship between pressure and volume of a gas– Gases fill container; if container size reduced
increased pressure
• Pressure (P) varies inversely with volume (V): – P1V1 = P2V2
© 2013 Pearson Education, Inc.
Inspiration
• Active process– Inspiratory muscles (diaphragm and external
intercostals) contract – Thoracic volume increases intrapulmonary
pressure drops (to 1 mm Hg)– Lungs stretched and intrapulmonary volume
increases– Air flows into lungs, down its pressure
gradient, until Ppul = Patm
© 2013 Pearson Education, Inc.
Forced Inspiration
• Vigorous exercise, COPD accessory muscles (scalenes, sternocleidomastoid, pectoralis minor) further increase in thoracic cage size
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 1
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
Thoracic cavity volumeincreases.
Lungs are stretched;intrapulmonary volumeincreases.
Intrapulmonary pressuredrops (to –1 mm Hg).
Air (gases) flows intolungs down its pressuregradient until intrapulmonarypressure is 0 (equal toatmospheric pressure).
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
2
3
4
5Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 2
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 3
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
Thoracic cavity volumeincreases.
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
2
Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 4
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
Thoracic cavity volumeincreases.
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
2
3
Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.
Lungs are stretched;intrapulmonary volumeincreases.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 5
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
Thoracic cavity volumeincreases.
Lungs are stretched;intrapulmonary volumeincreases.
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
2
3
4
Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.Intrapulmonary pressure
drops (to –1 mm Hg).
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (1 of 2) Slide 6
Inspiratory musclescontract (diaphragmdescends; rib cage rises).
Thoracic cavity volumeincreases.
Lungs are stretched;intrapulmonary volumeincreases.
Intrapulmonary pressuredrops (to –1 mm Hg).
Air (gases) flows intolungs down its pressuregradient until intrapulmonarypressure is 0 (equal toatmospheric pressure).
Insp
irati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
1
2
3
4
5Diaphragmmoves inferiorlyduringcontraction.
Ribs areelevated and sternumflares asexternalintercostalscontract.
Externalintercostalscontract.
© 2013 Pearson Education, Inc.
Expiration
• Quiet expiration normally passive process– Inspiratory muscles relax – Thoracic cavity volume decreases– Elastic lungs recoil and intrapulmonary
volume decreases pressure increases (Ppul rises to +1 mm Hg)
– Air flows out of lungs down its pressure gradient until Ppul = 0
• Note: forced expiration-active process; uses abdominal (oblique and transverse) and internal intercostal muscles
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 1
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
2
3
4
5 Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
Thoracic cavity volumedecreases.
Elastic lungs recoilpassively; intrapulmonaryVolume decreases.
Intrapulmonary pressurerises (to +1 mm Hg).
Air (gases) flows out oflungs down its pressuregradient until intrapulmonarypressure is 0.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 2
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 3
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
2
Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
Thoracic cavity volumedecreases.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 4
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
2
3
Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
Thoracic cavity volumedecreases.
Elastic lungs recoilpassively; intrapulmonaryVolume decreases.
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 5
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
2
3
4
Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
Thoracic cavity volumedecreases.
Elastic lungs recoilpassively; intrapulmonaryVolume decreases.
Intrapulmonary pressurerises (to +1 mm Hg).
© 2013 Pearson Education, Inc.
Figure 22.13 Changes in thoracic volume and sequence of events during inspiration and expiration. (2 of 2) Slide 6
1
Expir
ati
on
Sequence of events Changes in anterior-posterior andsuperior-inferior dimensions
Changes in lateral dimensions(superior view)
2
3
4
5 Diaphragmmovessuperiorlyas it relaxes.
Ribs andsternum aredepressedas externalintercostalsrelax.
Externalintercostalsrelax.
Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).
Thoracic cavity volumedecreases.
Elastic lungs recoilpassively; intrapulmonaryVolume decreases.
Intrapulmonary pressurerises (to +1 mm Hg).
Air (gases) flows out oflungs down its pressuregradient until intrapulmonarypressure is 0.
© 2013 Pearson Education, Inc.
Figure 22.14 Changes in intrapulmonary and intrapleural pressures during inspiration and expiration.
Intrapulmonary pressure. Pressure inside lungdecreases as lung volume increases duringinspiration; pressureincreases during expiration.
Intrapleural pressure.Pleural cavity pressure becomes more negative as chest wall expands during inspiration. Returns to initial value as chest wall recoils.
Volume of breath. During each breath, the pressure gradients move 0.5 liter ofair into and out of the lungs.
Pre
ssure
rela
tive t
oatm
osp
heri
c pre
ssure
(m
m H
g)
Volu
me (
L)
Inspiration Expiration
Intrapulmonarypressure
Trans-pulmonarypressure
Intrapleuralpressure
Volume of breath
5 seconds elapsed
+2
0
–2
–4
–6
–8
0.5
0
© 2013 Pearson Education, Inc.
Physical Factors Influencing Pulmonary Ventilation
• Three factors hinder air passage and pulmonary ventilation; require energy to overcome– Airway resistance– Alveolar surface tension– Lung compliance
© 2013 Pearson Education, Inc.
Airway Resistance
• Friction-major nonelastic source of resistance to gas flow; occurs in airways
• Relationship between flow (F), pressure (P), and resistance (R) is:
– ∆P - pressure gradient between atmosphere and alveoli (2 mm Hg or less during normal quiet breathing)
– Gas flow changes inversely with resistance
© 2013 Pearson Education, Inc.
Airway Resistance
• Resistance usually insignificant– Large airway diameters in first part of
conducting zone– Progressive branching of airways as get
smaller, increasing total cross-sectional area– Resistance greatest in medium-sized bronchi
• Resistance disappears at terminal bronchioles where diffusion drives gas movement
© 2013 Pearson Education, Inc.
Conductingzone
Respiratoryzone
Medium-sizedbronchi
Resi
stan
ce
Terminalbronchioles
1 5 10 15 20 23Airway generation
(stage of branching)
Figure 22.15 Resistance in respiratory passageways.
© 2013 Pearson Education, Inc.
Homeostatic Imbalance
• As airway resistance rises, breathing movements become more strenuous
• Severe constriction or obstruction of bronchioles– Can prevent life-sustaining ventilation– Can occur during acute asthma attacks; stops
ventilation
• Epinephrine dilates bronchioles, reduces air resistance
© 2013 Pearson Education, Inc.
Alveolar Surface Tension
• Surface tension– Attracts liquid molecules to one another at
gas-liquid interface – Resists any force that tends to increase
surface area of liquid– Water–high surface tension; coats alveolar
walls reduces them to smallest size
© 2013 Pearson Education, Inc.
Alveolar Surface Tension
• Surfactant– Detergent-like lipid and protein complex
produced by type II alveolar cells– Reduces surface tension of alveolar fluid and
discourages alveolar collapse– Insufficient quantity in premature infants
causes infant respiratory distress syndrome alveoli collapse after each breath
© 2013 Pearson Education, Inc.
Lung Compliance
• Measure of change in lung volume that occurs with given change in transpulmonary pressure
• Higher lung compliance easier to expand lungs
• Normally high due to– Distensibility of lung tissue – Alveolar surface tension
© 2013 Pearson Education, Inc.
Lung Compliance
• Diminished by– Nonelastic scar tissue replacing lung tissue
(fibrosis) – Reduced production of surfactant– Decreased flexibility of thoracic cage
© 2013 Pearson Education, Inc.
Lung Compliance
• Homeostatic imbalances that reduce compliance – Deformities of thorax– Ossification of costal cartilage– Paralysis of intercostal muscles
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