respiratory system consists of the respiratory and conducting zones consists of the respiratory and...

Respiratory SystemRespiratory System

Consists of the respiratory and conducting Consists of the respiratory and conducting zoneszones

Respiratory zone:Respiratory zone: Site of gas exchange Site of gas exchange Consists of bronchioles, alveolar ducts, and alveoliConsists of bronchioles, alveolar ducts, and alveoli


Conducting zone: Conducting zone: Conduits for air to reach the sites of gas exchangeConduits for air to reach the sites of gas exchange Includes all other respiratory structures (e.g., nose, Includes all other respiratory structures (e.g., nose,

nasal cavity, pharynx, trachea)nasal cavity, pharynx, trachea) Respiratory muscles – diaphragm and other Respiratory muscles – diaphragm and other

muscles that promote ventilationmuscles that promote ventilation


Figure 22.1

Major Functions of the Major Functions of the Respiratory SystemRespiratory System

To supply the body with oxygen and dispose To supply the body with oxygen and dispose of carbon dioxideof carbon dioxide

Respiration – four distinct processes must Respiration – four distinct processes must happenhappen Pulmonary ventilation – moving air into and out of Pulmonary ventilation – moving air into and out of

the lungsthe lungs External respiration – gas exchange between the External respiration – gas exchange between the

lungs and the bloodlungs and the blood

Major Functions of the Major Functions of the Respiratory SystemRespiratory System

Transport – transport of oxygen and carbon Transport – transport of oxygen and carbon dioxide between the lungs and tissuesdioxide between the lungs and tissues

Internal respiration – gas exchange between Internal respiration – gas exchange between systemic blood vessels and tissuessystemic blood vessels and tissues

Function of the NoseFunction of the Nose

The only externally visible part of the The only externally visible part of the respiratory system that functions by:respiratory system that functions by: Providing an airway for respirationProviding an airway for respiration Moistening and warming the entering airMoistening and warming the entering air Filtering inspired air and cleaning it of foreign Filtering inspired air and cleaning it of foreign

mattermatter Serving as a resonating chamber for speechServing as a resonating chamber for speech Housing the olfactory receptorsHousing the olfactory receptors

Structure of the NoseStructure of the Nose

Nose is divided into two regions:Nose is divided into two regions: External nose, including the root, bridge, dorsum External nose, including the root, bridge, dorsum

nasi, and apex nasi, and apex Internal nasal cavityInternal nasal cavity

Nasal CavityNasal Cavity

Lies in and posterior to the external noseLies in and posterior to the external nose Is divided by a midline nasal septumIs divided by a midline nasal septum Opens posteriorly into the nasal pharynx via Opens posteriorly into the nasal pharynx via

internal naresinternal nares The ethmoid and sphenoid bones form the roofThe ethmoid and sphenoid bones form the roof The floor is formed by the hard and soft The floor is formed by the hard and soft

palatespalates


Vestibule – nasal cavity superior to the nares Vestibule – nasal cavity superior to the nares Vibrissae – hairs that filter coarse particles from Vibrissae – hairs that filter coarse particles from

inspired airinspired air Olfactory mucosaOlfactory mucosa

Lines the superior nasal cavity Lines the superior nasal cavity Contains smell receptorsContains smell receptors


Respiratory mucosa Respiratory mucosa Lines the balance of the nasal cavity Lines the balance of the nasal cavity Glands secrete mucus containing lysozyme and Glands secrete mucus containing lysozyme and

defensins to help destroy bacteriadefensins to help destroy bacteria


Inspired air is: Inspired air is: Humidified by the high water content in the nasal Humidified by the high water content in the nasal

cavitycavity Warmed by rich plexuses of capillariesWarmed by rich plexuses of capillaries

Ciliated mucosal cells remove contaminated Ciliated mucosal cells remove contaminated mucus mucus


Superior, medial, and inferior conchae:Superior, medial, and inferior conchae: Protrude medially from the lateral wallsProtrude medially from the lateral walls Increase mucosal areaIncrease mucosal area Enhance air turbulence and help filter airEnhance air turbulence and help filter air

Sensitive mucosa triggers sneezing when Sensitive mucosa triggers sneezing when stimulated by irritating particlesstimulated by irritating particles

Functions of the Nasal Mucosa Functions of the Nasal Mucosa and Conchaeand Conchae

During inhalation the conchae and nasal During inhalation the conchae and nasal mucosa:mucosa: Filter, heat, and moisten airFilter, heat, and moisten air

During exhalation these structures:During exhalation these structures: Reclaim heat and moistureReclaim heat and moisture Minimize heat and moisture lossMinimize heat and moisture loss

Paranasal SinusesParanasal Sinuses

Sinuses in bones that surround the nasal cavitySinuses in bones that surround the nasal cavity Sinuses lighten the skull and help to warm and Sinuses lighten the skull and help to warm and

moisten the airmoisten the air

PharynxPharynx

Funnel-shaped tube of skeletal muscle that Funnel-shaped tube of skeletal muscle that connects to the:connects to the: Nasal cavity and mouth superiorlyNasal cavity and mouth superiorly Larynx and esophagus inferiorlyLarynx and esophagus inferiorly

Extends from the base of the skull to the level Extends from the base of the skull to the level of the sixth cervical vertebraof the sixth cervical vertebra

PharynxPharynx

It is divided into three regionsIt is divided into three regions Nasopharynx: posterior to the nasal cavity; air Nasopharynx: posterior to the nasal cavity; air

passageway; lined with pseudostratified columnar passageway; lined with pseudostratified columnar epithelium; auditory tubes open into epithelium; auditory tubes open into

Oropharynx: extends from the soft palate to the Oropharynx: extends from the soft palate to the epiglottis; opens to the oral cavity; common epiglottis; opens to the oral cavity; common passageway for food and air; stratified squamous passageway for food and air; stratified squamous epithelium linesepithelium lines

Laryngopharynx: common passageway for food Laryngopharynx: common passageway for food and air; posterior to the epiglottis; extends to the and air; posterior to the epiglottis; extends to the larynxlarynx

Larynx (Voice Box)Larynx (Voice Box)

Attaches to the hyoid bone and opens into the Attaches to the hyoid bone and opens into the laryngopharynx superiorlylaryngopharynx superiorly

Continuous with the trachea posteriorlyContinuous with the trachea posteriorly The three functions of the larynx are:The three functions of the larynx are:

To provide a patent airwayTo provide a patent airway To act as a switching mechanism to route air and To act as a switching mechanism to route air and

food into the proper channelsfood into the proper channels To function in voice productionTo function in voice production

Framework of the LarynxFramework of the Larynx

Cartilages (hyaline) of the larynxCartilages (hyaline) of the larynx Shield-shaped thyroid cartilage with a midline Shield-shaped thyroid cartilage with a midline

laryngeal prominence (Adam’s apple)laryngeal prominence (Adam’s apple) Signet ring–shaped cricoid cartilageSignet ring–shaped cricoid cartilage Three pairs of small arytenoid, cuneiform, and Three pairs of small arytenoid, cuneiform, and

corniculate cartilagescorniculate cartilages Epiglottis – elastic cartilage that covers the Epiglottis – elastic cartilage that covers the

laryngeal inlet during swallowinglaryngeal inlet during swallowing

Framework of the LarynxFramework of the Larynx

Figure 22.4a, b

Vocal LigamentsVocal Ligaments

Attach the arytenoid cartilages to the thyroid Attach the arytenoid cartilages to the thyroid cartilagecartilage

Composed of elastic fibers that form mucosal Composed of elastic fibers that form mucosal folds called true vocal cordsfolds called true vocal cords The medial opening between them is the glottisThe medial opening between them is the glottis They vibrate to produce sound as air rushes up They vibrate to produce sound as air rushes up

from the lungsfrom the lungs

Vocal LigamentsVocal Ligaments

False vocal cordsFalse vocal cords Mucosal folds superior to the true vocal cordsMucosal folds superior to the true vocal cords Have no part in sound productionHave no part in sound production

Vocal ProductionVocal Production Speech – intermittent release of expired air Speech – intermittent release of expired air

while opening and closing the glottiswhile opening and closing the glottis Pitch – determined by the length and tension of Pitch – determined by the length and tension of

the vocal cords the vocal cords Loudness – depends upon the force at which Loudness – depends upon the force at which

the air rushes across the vocal cordsthe air rushes across the vocal cords The pharynx resonates, amplifies, and The pharynx resonates, amplifies, and

enhances sound qualityenhances sound quality Sound is “shaped” into language by action of Sound is “shaped” into language by action of

the pharynx, tongue, soft palate, and lipsthe pharynx, tongue, soft palate, and lips

Movements of Vocal CordsMovements of Vocal Cords

Figure 22.5

Sphincter Functions of the Sphincter Functions of the LarynxLarynx

The larynx is closed during coughing, sneezing, The larynx is closed during coughing, sneezing, and Valsalva’s maneuver and Valsalva’s maneuver

Valsalva’s maneuverValsalva’s maneuver Air is temporarily held in the lower respiratory tract Air is temporarily held in the lower respiratory tract

by closing the glottis by closing the glottis Causes intra-abdominal pressure to rise when Causes intra-abdominal pressure to rise when

abdominal muscles contractabdominal muscles contract Helps to empty the rectumHelps to empty the rectum Acts as a splint to stabilize the trunk when lifting Acts as a splint to stabilize the trunk when lifting

heavy loadsheavy loads

TracheaTrachea

Flexible and mobile tube extending from the Flexible and mobile tube extending from the larynx into the mediastinumlarynx into the mediastinum

Composed of three layersComposed of three layers Mucosa – made up of goblet cells and ciliated Mucosa – made up of goblet cells and ciliated

epithelium epithelium Submucosa – connective tissue deep to the mucosaSubmucosa – connective tissue deep to the mucosa Adventitia – outermost layer made of C-shaped Adventitia – outermost layer made of C-shaped

rings of hyaline cartilagerings of hyaline cartilage

Conducting Zone: BronchiConducting Zone: Bronchi

Last tracheal cartilage marks the end of the Last tracheal cartilage marks the end of the trachea and the beginning of the bronchitrachea and the beginning of the bronchi

Air reaching the bronchi is:Air reaching the bronchi is: Warm and cleansed of impuritiesWarm and cleansed of impurities Saturated with water vaporSaturated with water vapor

Bronchi subdivide into secondary bronchi, Bronchi subdivide into secondary bronchi, each supplying a lobe of the lungseach supplying a lobe of the lungs

Air passages undergo 23 orders of branchingAir passages undergo 23 orders of branching

Conducting Zone: Bronchial Conducting Zone: Bronchial TreeTree

Tissue walls of bronchi mimic that of the Tissue walls of bronchi mimic that of the tracheatrachea

As conducting tubes become smaller, As conducting tubes become smaller, structural changes occurstructural changes occur Cartilage support structures changeCartilage support structures change Epithelium types changeEpithelium types change Amount of smooth muscle increasesAmount of smooth muscle increases

Conducting Zone: Bronchial Conducting Zone: Bronchial TreeTree

Bronchioles Bronchioles Consist of cuboidal epitheliumConsist of cuboidal epithelium Have a complete layer of circular smooth muscle Have a complete layer of circular smooth muscle Lack cartilage support and mucus-producing cellsLack cartilage support and mucus-producing cells

Conducting ZonesConducting Zones

Figure 22.7

Respiratory ZoneRespiratory Zone

Defined by the presence of alveoli; begins as Defined by the presence of alveoli; begins as terminal bronchioles feed into respiratory terminal bronchioles feed into respiratory bronchiolesbronchioles

Respiratory bronchioles lead to alveolar ducts, Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs then to terminal clusters of alveolar sacs composed of alveolicomposed of alveoli

Approximately 300 million alveoli:Approximately 300 million alveoli: Account for most of the lungs’ volume Account for most of the lungs’ volume Provide tremendous surface area for gas exchangeProvide tremendous surface area for gas exchange


Figure 22.8a


Figure 22.8b

Respiratory MembraneRespiratory Membrane

This air-blood barrier is composed of: This air-blood barrier is composed of: Alveolar and capillary wallsAlveolar and capillary walls Their fused basal laminasTheir fused basal laminas

Alveolar walls:Alveolar walls: Are a single layer of type I epithelial cellsAre a single layer of type I epithelial cells Permit gas exchange by simple diffusionPermit gas exchange by simple diffusion Secrete angiotensin converting enzyme (ACE)Secrete angiotensin converting enzyme (ACE)

Type II cells secrete surfactantType II cells secrete surfactant

AlveoliAlveoli

Surrounded by fine elastic fibersSurrounded by fine elastic fibers Contain open pores that:Contain open pores that:

Connect adjacent alveoliConnect adjacent alveoli Allow air pressure throughout the lung to be Allow air pressure throughout the lung to be

equalizedequalized House macrophages that keep alveolar House macrophages that keep alveolar

surfaces sterilesurfaces sterile

Gross Anatomy of the LungsGross Anatomy of the Lungs

Lungs occupy all of the thoracic cavity except Lungs occupy all of the thoracic cavity except the mediastinumthe mediastinum Root – site of vascular and bronchial attachmentsRoot – site of vascular and bronchial attachments Costal surface – anterior, lateral, and posterior Costal surface – anterior, lateral, and posterior

surfaces in contact with the ribssurfaces in contact with the ribs Apex – narrow superior tipApex – narrow superior tip Base – inferior surface that rests on the diaphragmBase – inferior surface that rests on the diaphragm Hilus – indentation that contains pulmonary and Hilus – indentation that contains pulmonary and

systemic blood vesselssystemic blood vessels

Organs in the Thoracic CavityOrgans in the Thoracic Cavity

Figure 22.10a

Transverse Thoracic SectionTransverse Thoracic Section

Figure 22.10c

LungsLungs

Cardiac notch (impression) – cavity that Cardiac notch (impression) – cavity that accommodates the heartaccommodates the heart

Left lung – separated into upper and lower Left lung – separated into upper and lower lobes by the oblique fissurelobes by the oblique fissure

Right lung – separated into three lobes by the Right lung – separated into three lobes by the oblique and horizontal fissuresoblique and horizontal fissures

There are 10 bronchopulmonary segments in There are 10 bronchopulmonary segments in each lungeach lung

Blood Supply to LungsBlood Supply to Lungs

Lungs are perfused by two circulations: Lungs are perfused by two circulations: pulmonary and bronchialpulmonary and bronchial

Pulmonary arteries – supply systemic venous Pulmonary arteries – supply systemic venous blood to be oxygenatedblood to be oxygenated Branch profusely, along with bronchiBranch profusely, along with bronchi Ultimately feed into the pulmonary capillary Ultimately feed into the pulmonary capillary

network surrounding the alveolinetwork surrounding the alveoli Pulmonary veins – carry oxygenated blood Pulmonary veins – carry oxygenated blood

from respiratory zones to the heartfrom respiratory zones to the heart

Blood Supply to LungsBlood Supply to Lungs

Bronchial arteries – provide systemic blood to Bronchial arteries – provide systemic blood to the lung tissuethe lung tissue Arise from aorta and enter the lungs at the hilusArise from aorta and enter the lungs at the hilus Supply all lung tissue except the alveoliSupply all lung tissue except the alveoli

Bronchial veins anastomose with pulmonary Bronchial veins anastomose with pulmonary veinsveins

Pulmonary veins carry most venous blood Pulmonary veins carry most venous blood back to the heartback to the heart

PleuraePleurae

Thin, double-layered serosa Thin, double-layered serosa Parietal pleuraParietal pleura

Covers the thoracic wall and superior face of the Covers the thoracic wall and superior face of the diaphragmdiaphragm

Continues around heart and between lungsContinues around heart and between lungs

PleuraePleurae

Visceral, or pulmonary, pleuraVisceral, or pulmonary, pleura Covers the external lung surfaceCovers the external lung surface Divides the thoracic cavity into three chambersDivides the thoracic cavity into three chambers

The central mediastinumThe central mediastinum Two lateral compartments, each containing a lung Two lateral compartments, each containing a lung

BreathingBreathing

Breathing, or pulmonary ventilation, consists Breathing, or pulmonary ventilation, consists of two phasesof two phases Inspiration – air flows into the lungsInspiration – air flows into the lungs Expiration – gases exit the lungsExpiration – gases exit the lungs

Pressure Relationships in the Pressure Relationships in the Thoracic CavityThoracic Cavity

Respiratory pressure is always described Respiratory pressure is always described relative to atmospheric pressurerelative to atmospheric pressure

Atmospheric pressure (PAtmospheric pressure (Patmatm)) Pressure exerted by the air surrounding the body Pressure exerted by the air surrounding the body Negative respiratory pressure is less than PNegative respiratory pressure is less than Patmatm

Positive respiratory pressure is greater than PPositive respiratory pressure is greater than Patmatm

Pressure Relationships in the Pressure Relationships in the Thoracic CavityThoracic Cavity

Intrapulmonary pressure (PIntrapulmonary pressure (Ppulpul) – pressure ) – pressure

within the alveoliwithin the alveoli Intrapleural pressure (PIntrapleural pressure (Pipip) – pressure within the ) – pressure within the

pleural cavitypleural cavity

Pressure RelationshipsPressure Relationships

Intrapulmonary pressure and intrapleural Intrapulmonary pressure and intrapleural pressure fluctuate with the phases of breathingpressure fluctuate with the phases of breathing

Intrapulmonary pressure always eventually Intrapulmonary pressure always eventually equalizes itself with atmospheric pressureequalizes itself with atmospheric pressure

Intrapleural pressure is always less than Intrapleural pressure is always less than intrapulmonary pressure and atmospheric intrapulmonary pressure and atmospheric pressurepressure


Two forces act to pull the lungs away from the Two forces act to pull the lungs away from the thoracic wall, promoting lung collapsethoracic wall, promoting lung collapse Elasticity of lungs causes them to assume smallest Elasticity of lungs causes them to assume smallest

possible sizepossible size Surface tension of alveolar fluid draws alveoli to Surface tension of alveolar fluid draws alveoli to

their smallest possible sizetheir smallest possible size Opposing force – elasticity of the chest wall Opposing force – elasticity of the chest wall

pulls the thorax outward to enlarge the lungspulls the thorax outward to enlarge the lungs


Figure 22.12

Lung CollapseLung Collapse

Caused by equalization of the intrapleural Caused by equalization of the intrapleural pressure with the intrapulmonary pressurepressure with the intrapulmonary pressure

Transpulmonary pressure keeps the airways Transpulmonary pressure keeps the airways openopen

Pulmonary VentilationPulmonary Ventilation

A mechanical process that depends on volume A mechanical process that depends on volume changes in the thoracic cavitychanges in the thoracic cavity

Volume changes lead to pressure changes, Volume changes lead to pressure changes, which lead to the flow of gases to equalize which lead to the flow of gases to equalize pressurepressure

Boyle’s LawBoyle’s Law

Boyle’s law – the relationship between the Boyle’s law – the relationship between the pressure and volume of gases pressure and volume of gases

PP11VV11 = P = P22VV22

P = pressure of a gas in mm HgP = pressure of a gas in mm Hg V = volume of a gas in cubic millimetersV = volume of a gas in cubic millimeters Subscripts 1 and 2 represent the initial and Subscripts 1 and 2 represent the initial and

resulting conditions, respectivelyresulting conditions, respectively

InspirationInspiration

The diaphragm and external intercostal muscles The diaphragm and external intercostal muscles (inspiratory muscles) contract and the rib cage (inspiratory muscles) contract and the rib cage risesrises

The lungs are stretched and intrapulmonary The lungs are stretched and intrapulmonary volume increasesvolume increases

Intrapulmonary pressure drops below Intrapulmonary pressure drops below atmospheric pressure (atmospheric pressure (1 mm Hg)1 mm Hg)

Air flows into the lungs, down its pressure Air flows into the lungs, down its pressure gradient, until intrapleural pressure = gradient, until intrapleural pressure = atmospheric pressureatmospheric pressure

ExpirationExpiration

Inspiratory muscles relax and the rib cage Inspiratory muscles relax and the rib cage descends due to gravitydescends due to gravity

Thoracic cavity volume decreasesThoracic cavity volume decreases Elastic lungs recoil passively and Elastic lungs recoil passively and

intrapulmonary volume decreasesintrapulmonary volume decreases Intrapulmonary pressure rises above Intrapulmonary pressure rises above

atmospheric pressure (+1 mm Hg)atmospheric pressure (+1 mm Hg) Gases flow out of the lungs down the pressure Gases flow out of the lungs down the pressure

gradient until intrapulmonary pressure is 0gradient until intrapulmonary pressure is 0

Friction is the major nonelastic source of Friction is the major nonelastic source of resistance to airflowresistance to airflow

Physical Factors Influencing Physical Factors Influencing Ventilation: Ventilation:

Airway ResistanceAirway Resistance

The amount of gas flowing into and out of the The amount of gas flowing into and out of the alveoli is directly proportional to alveoli is directly proportional to P, the P, the pressure gradient between the atmosphere and pressure gradient between the atmosphere and the alveolithe alveoli

Gas flow is inversely proportional to resistance Gas flow is inversely proportional to resistance with the greatest resistance being in the with the greatest resistance being in the medium-sized bronchimedium-sized bronchi

Physical Factors Influencing Physical Factors Influencing Ventilation: Ventilation:



As airway resistance rises, breathing As airway resistance rises, breathing movements become more strenuousmovements become more strenuous

Severely constricted or obstructed bronchioles: Severely constricted or obstructed bronchioles: Can prevent life-sustaining ventilationCan prevent life-sustaining ventilation Can occur during acute asthma attacks which stops Can occur during acute asthma attacks which stops

ventilationventilation Epinephrine release via the sympathetic Epinephrine release via the sympathetic

nervous system dilates bronchioles and nervous system dilates bronchioles and reduces air resistancereduces air resistance

Alveolar Surface TensionAlveolar Surface Tension

Surface tension – the attraction of liquid Surface tension – the attraction of liquid molecules to one another at a liquid-gas molecules to one another at a liquid-gas interface interface

The liquid coating the alveolar surface is The liquid coating the alveolar surface is always acting to reduce the alveoli to the always acting to reduce the alveoli to the smallest possible sizesmallest possible size

Surfactant, a detergent-like complex, reduces Surfactant, a detergent-like complex, reduces surface tension and helps keep the alveoli from surface tension and helps keep the alveoli from collapsingcollapsing

Lung ComplianceLung Compliance

The ease with which lungs can be expandedThe ease with which lungs can be expanded Specifically, the measure of the change in lung Specifically, the measure of the change in lung

volume that occurs with a given change in volume that occurs with a given change in transpulmonary pressuretranspulmonary pressure

Determined by two main factorsDetermined by two main factors Distensibility of the lung tissue and surrounding Distensibility of the lung tissue and surrounding

thoracic cagethoracic cage Surface tension of the alveoliSurface tension of the alveoli

Factors That Diminish Lung Factors That Diminish Lung ComplianceCompliance

Scar tissue or fibrosis that reduces the natural Scar tissue or fibrosis that reduces the natural resilience of the lungsresilience of the lungs

Blockage of the smaller respiratory passages Blockage of the smaller respiratory passages with mucus or fluidwith mucus or fluid

Reduced production of surfactantReduced production of surfactant Decreased flexibility of the thoracic cage or its Decreased flexibility of the thoracic cage or its

decreased ability to expanddecreased ability to expand

Factors That Diminish Lung Factors That Diminish Lung ComplianceCompliance

Examples include: Examples include: Deformities of thoraxDeformities of thorax Ossification of the costal cartilageOssification of the costal cartilage Paralysis of intercostal musclesParalysis of intercostal muscles

respiratory system consists of the respiratory and conducting zones consists of the respiratory and...

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