Essentials of Human Anatomy & Physiology

Seventh Edition

Elaine N. Marieb

Chapter 13

The Respiratory System

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Slides 13.1 – 13.30

The Respiratory System

Lecture Slides in PowerPoint by Jerry L. Cook

Organs of the Respiratory systemOrgans of the Respiratory system

Nose

Pharynx

Larynx

Slide 13.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Larynx

Trachea

Bronchi

Lungs –alveoli

Figure 13.1

Function of the Respiratory SystemFunction of the Respiratory System

Oversees gas exchanges between theblood and external environment

Exchange of gasses takes place within

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Exchange of gasses takes place withinthe lungs in the alveoli

Passageways to the lungs purify, warm,and humidify the incoming air

The NoseThe Nose

The only externally visible part of therespiratory system

Air enters the nose through the external

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Air enters the nose through the externalnares (nostrils)

The interior of the nose consists of anasal cavity divided by a nasal septum

Upper Respiratory TractUpper Respiratory Tract

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Figure 13.2

Anatomy of the Nasal CavityAnatomy of the Nasal Cavity

Olfactory receptors are located in themucosa on the superior surface

The rest of the cavity is lined with

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The rest of the cavity is lined withrespiratory mucosa

Moistens air

Traps incoming foreign particles

Anatomy of the Nasal CavityAnatomy of the Nasal Cavity

Lateral walls have projections calledconchae

Increases surface area

Increases air turbulence within the nasal

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Increases air turbulence within the nasalcavity

The nasal cavity is separated from theoral cavity by the palate

Anterior hard palate (bone)

Posterior soft palate (muscle)

Paranasal SinusesParanasal Sinuses

Cavities within bones surrounding thenasal cavity

Frontal bone

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Frontal bone

Sphenoid bone

Ethmoid bone

Maxillary bone

Paranasal SinusesParanasal Sinuses

Function of the sinuses

Lighten the skull

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Act as resonance chambers for speech

Produce mucus that drains into the nasalcavity

Pharynx (Throat)Pharynx (Throat)

Muscular passage from nasal cavity tolarynx

Three regions of the pharynx

Nasopharynx – superior region behindnasal cavity

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Nasopharynx – superior region behindnasal cavity

Oropharynx – middle region behind mouth

Laryngopharynx – inferior region attachedto larynx

The oropharynx and laryngopharynx arecommon passageways for air and food

Structures of the PharynxStructures of the Pharynx

Auditory tubes enter the nasopharynx

Tonsils of the pharynx

Pharyngeal tonsil (adenoids) in the

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Pharyngeal tonsil (adenoids) in thenasopharynx

Palatine tonsils in the oropharynx

Lingual tonsils at the base of the tongue

Larynx (Voice Box)Larynx (Voice Box)

Routes air and food into properchannels

Plays a role in speech

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Plays a role in speech

Made of eight rigid hyaline cartilagesand a spoon-shaped flap of elasticcartilage (epiglottis)

Structures of the LarynxStructures of the Larynx

Thyroid cartilage

Largest hyaline cartilage

Protrudes anteriorly (Adam’s apple)

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Protrudes anteriorly (Adam’s apple)

Epiglottis

Superior opening of the larynx

Routes food to the larynx and air towardthe trachea

Structures of the LarynxStructures of the Larynx

Vocal cords (vocal folds)

Vibrate with expelled air to create sound

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Vibrate with expelled air to create sound(speech)

Glottis – opening between vocal cords

Trachea (Windpipe)Trachea (Windpipe)

Connects larynx with bronchi

Lined with ciliated mucosa

Beat continuously in the opposite direction ofincoming air

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incoming air

Expel mucus loaded with dust and otherdebris away from lungs

Walls are reinforced with C-shapedhyaline cartilage

Primary BronchiPrimary Bronchi

Formed by division of the trachea

Enters the lung at the hilus(medial depression)

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Right bronchus is wider, shorter,and straighter than left

Bronchi subdivide into smallerand smaller branches

LungsLungs

Occupy most of the thoracic cavity

Apex is near the clavicle (superior portion)

Base rests on the diaphragm (inferior

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Base rests on the diaphragm (inferiorportion)

Each lung is divided into lobes by fissures

Left lung – two lobes

Right lung – three lobes

LungsLungs

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Figure 13.4b

Coverings of the LungsCoverings of the Lungs

Pulmonary (visceral) pleura covers thelung surface

Parietal pleura lines the walls of the

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Parietal pleura lines the walls of thethoracic cavity

Pleural fluid fills the area betweenlayers of pleura to allow gliding

Respiratory Tree DivisionsRespiratory Tree Divisions

Primary bronchi

Secondary bronchi

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Tertiary bronchi

Bronchioli

Terminal bronchioli

BronchiolesBronchioles

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Figure 13.5a

Smallestbranches ofthe bronchi

BronchiolesBronchioles

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Figure 13.5a

All but the smallestbranches havereinforcing cartilage

BronchiolesBronchioles

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Terminalbronchioles endin alveoli

Figure 13.5a

Respiratory ZoneRespiratory Zone

Structures

Respiratory bronchioli

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Alveolar duct

Alveoli

Site of gas exchange

AlveoliAlveoli

Structure of alveoli

Alveolar duct

Alveolar sac

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Alveolar sac

Alveolus

Gas exchange takes place within the alveoliin the respiratory membrane

Respiratory MembraneRespiratory Membrane(Air(Air--Blood Barrier)Blood Barrier)

Thin squamous epithelial layer liningalveolar walls

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alveolar walls

Pulmonary capillaries cover externalsurfaces of alveoli

Respiratory MembraneRespiratory Membrane(Air(Air--Blood Barrier)Blood Barrier)

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Figure 13.6

Gas ExchangeGas Exchange

Gas crosses the respiratory membraneby diffusion

Oxygen enters the blood

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Carbon dioxide enters the alveoli

Macrophages add protection

Surfactant coats gas-exposed alveolarsurfaces

Events of RespirationEvents of Respiration

Pulmonary ventilation – moving air in andout of the lungs

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out of the lungs

External respiration – gas exchangebetween pulmonary blood and alveoli

Events of RespirationEvents of Respiration

Respiratory gas transport – transport ofoxygen and carbon dioxide via thebloodstream

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bloodstream

Internal respiration – gas exchangebetween blood and tissue cells insystemic capillaries

Mechanics of BreathingMechanics of Breathing(Pulmonary Ventilation)(Pulmonary Ventilation)

Completely mechanical process

Depends on volume changes in thethoracic cavity

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thoracic cavity

Volume changes lead to pressurechanges, which lead to the flow ofgases to equalize pressure

Mechanics of BreathingMechanics of Breathing(Pulmonary Ventilation)(Pulmonary Ventilation)

Two phases

Inspiration – flow of air into lung

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Inspiration – flow of air into lung

Expiration – air leaving lung

InspirationInspiration

Diaphragm and intercostal musclescontract

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The size of the thoracic cavity increases

External air is pulled into the lungs due toan increase in intrapulmonary volume

InspirationInspiration

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Figure 13.7a

ExhalationExhalation

Largely a passive process which dependson natural lung elasticity

As muscles relax, air is pushed out of the

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As muscles relax, air is pushed out of thelungs

Forced expiration can occur mostly bycontracting internal intercostal muscles todepress the rib cage

ExhalationExhalation

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Figure 13.7b

Pressure Differences in thePressure Differences in theThoracic CavityThoracic Cavity

Normal pressure within the pleuralspace is always negative (intrapleuralpressure)

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pressure)

Differences in lung and pleural spacepressures keep lungs from collapsing

Nonrespiratory Air MovementsNonrespiratory Air Movements

Can be caused by reflexes or voluntaryactions

Examples

Cough and sneeze – clears lungs of debris

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Cough and sneeze – clears lungs of debris

Laughing

Crying

Yawn

Hiccup

Respiratory Volumes and CapacitiesRespiratory Volumes and Capacities

Normal breathing moves about 500 ml of airwith each breath (tidal volume [TV])

Many factors that affect respiratory capacity

A person’s size

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A person’s size

Sex

Age

Physical condition

Residual volume of air – after exhalation,about 1200 ml of air remains in the lungs

Respiratory Volumes and CapacitiesRespiratory Volumes and Capacities

Inspiratory reserve volume (IRV)

Amount of air that can be taken in forciblyover the tidal volume

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Usually between 2100 and 3200 ml

Expiratory reserve volume (ERV)

Amount of air that can be forcibly exhaled

Approximately 1200 ml

Respiratory Volumes and CapacitiesRespiratory Volumes and Capacities

Residual volume

Air remaining in lung after expiration

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Air remaining in lung after expiration

About 1200 ml

Respiratory Volumes and CapacitiesRespiratory Volumes and Capacities

Vital capacity

The total amount of exchangeable air

Vital capacity = TV + IRV + ERV

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Vital capacity = TV + IRV + ERV

Dead space volume

Air that remains in conducting zone andnever reaches alveoli

About 150 ml

Respiratory Volumes and CapacitiesRespiratory Volumes and Capacities

Functional volume

Air that actually reaches the respiratoryzone

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zone

Usually about 350 ml

Respiratory capacities are measuredwith a spirometer

Respiratory CapacitiesRespiratory Capacities

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Figure 13.9

Respiratory SoundsRespiratory Sounds

Sounds are monitored with astethoscope

Bronchial sounds – produced by air

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Bronchial sounds – produced by airrushing through trachea and bronchi

Vesicular breathing sounds – softsounds of air filling alveoli

External RespirationExternal Respiration

Oxygen movement into the blood

The alveoli always has more oxygen thanthe blood

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the blood

Oxygen moves by diffusion towards thearea of lower concentration

Pulmonary capillary blood gains oxygen

External RespirationExternal Respiration

Carbon dioxide movement out of theblood

Blood returning from tissues has higherconcentrations of carbon dioxide than air in

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concentrations of carbon dioxide than air inthe alveoli

Pulmonary capillary blood gives up carbondioxide

Blood leaving the lungs is oxygen-richand carbon dioxide-poor

Gas Transport in the BloodGas Transport in the Blood

Oxygen transport in the blood

Inside red blood cells attached to

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Inside red blood cells attached tohemoglobin (oxyhemoglobin [HbO2])

A small amount is carried dissolved in theplasma

Gas Transport in the BloodGas Transport in the Blood

Carbon dioxide transport in the blood

Most is transported in the plasma as

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Most is transported in the plasma asbicarbonate ion (HCO3

–)

A small amount is carried inside red bloodcells on hemoglobin, but at different bindingsites than those of oxygen

Internal RespirationInternal Respiration

Exchange of gases between blood andbody cells

An opposite reaction to what occurs in

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An opposite reaction to what occurs inthe lungs

Carbon dioxide diffuses out of tissue toblood

Oxygen diffuses from blood into tissue

Internal RespirationInternal Respiration

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Figure 13.11

External Respiration,External Respiration,Gas Transport, andGas Transport, andInternal RespirationInternal RespirationSummarySummary

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Figure 13.10

Neural Regulation of RespirationNeural Regulation of Respiration

Activity of respiratory muscles is transmittedto the brain by the phrenic and intercostalnerves

Neural centers that control rate and depth arelocated in the medulla

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located in the medulla

The pons appears to smooth out respiratoryrate

Normal respiratory rate (eupnea) is 12–15respirations per minute

Hypernia is increased respiratory rate oftendue to extra oxygen needs

Neural Regulation of RespirationNeural Regulation of Respiration

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Figure 13.12

Factors Influencing RespiratoryFactors Influencing RespiratoryRate and DepthRate and Depth

Physical factors

Increased body temperature

Exercise

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Exercise

Talking

Coughing

Volition (conscious control)

Emotional factors

Factors Influencing RespiratoryFactors Influencing RespiratoryRate and DepthRate and Depth

Chemical factors

Carbon dioxide levels

Level of carbon dioxide in the blood is the

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Level of carbon dioxide in the blood is themain regulatory chemical for respiration

Increased carbon dioxide increasesrespiration

Changes in carbon dioxide act directly onthe medulla oblongata

Factors Influencing RespiratoryFactors Influencing RespiratoryRate and DepthRate and Depth

Chemical factors (continued)

Oxygen levels

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Oxygen levels

Changes in oxygen concentration in theblood are detected by chemoreceptors inthe aorta and carotid artery

Information is sent to the medulla oblongata

Respiratory Disorders: ChronicRespiratory Disorders: ChronicObstructive Pulmonary DiseaseObstructive Pulmonary Disease(COPD)(COPD)

Exemplified by chronic bronchitis andemphysema

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emphysema

Major causes of death and disability inthe United States

Respiratory Disorders: ChronicRespiratory Disorders: ChronicObstructive Pulmonary DiseaseObstructive Pulmonary Disease(COPD)(COPD)

Features of these diseases

Patients almost always have a history of

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Patients almost always have a history ofsmoking

Labored breathing (dyspnea) becomesprogressively more severe

Coughing and frequent pulmonaryinfections are common

Respiratory Disorders: ChronicRespiratory Disorders: ChronicObstructive Pulmonary DiseaseObstructive Pulmonary Disease(COPD)(COPD)

Features of these diseases (continued)

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Most victimes retain carbon dioxide, arehypoxic and have respiratory acidosis

Those infected will ultimately developrespiratory failure

EmphysemaEmphysema

Alveoli enlarge as adjacent chambers breakthrough

Chronic inflammation promotes lung fibrosis

Airways collapse during expiration

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Airways collapse during expiration

Patients use a large amount of energy toexhale

Overinflation of the lungs leads to apermanently expanded barrel chest

Cyanosis appears late in the disease

Chronic BronchitisChronic Bronchitis

Mucosa of the lower respiratorypassages becomes severely inflamed

Mucus production increases

Pooled mucus impairs ventilation and

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Pooled mucus impairs ventilation andgas exchange

Risk of lung infection increases

Pneumonia is common

Hypoxia and cyanosis occur early

Chronic Obstructive Pulmonary DiseaseChronic Obstructive Pulmonary Disease(COPD)(COPD)

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Figure 13.13

Lung CancerLung Cancer

Accounts for 1/3 of all cancer deaths inthe United States

Increased incidence associated withsmoking

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smoking

Three common types

Squamous cell carcinoma

Adenocarcinoma

Small cell carcinoma

Sudden Infant Death syndromeSudden Infant Death syndrome(SIDS)(SIDS)

Apparently healthy infant stopsbreathing and dies during sleep

Some cases are thought to be a

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Some cases are thought to be aproblem of the neural respiratory controlcenter

One third of cases appear to be due toheart rhythm abnormalities

AsthmaAsthma

Chronic inflamed hypersensitivebronchiole passages

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bronchiole passages

Response to irritants with dyspnea,coughing, and wheezing

Developmental Aspects of theDevelopmental Aspects of theRespiratory SystemRespiratory System

Lungs are filled with fluid in the fetus

Lungs are not fully inflated with air untiltwo weeks after birth

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two weeks after birth

Surfactant that lowers alveolar surfacetension is not present until late in fetaldevelopment and may not be present inpremature babies

Developmental Aspects of theDevelopmental Aspects of theRespiratory SystemRespiratory System

Important birth defects

Cystic fibrosis – oversecretion of thick

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Cystic fibrosis – oversecretion of thickmucus clogs the respiratory system

Cleft palate

Aging EffectsAging Effects

Elasticity of lungs decreases

Vital capacity decreases

Blood oxygen levels decrease

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Blood oxygen levels decrease

Stimulating effects of carbon dioxidedecreases

More risks of respiratory tract infection

Respiratory Rate ChangesRespiratory Rate ChangesThroughout LifeThroughout Life

Newborns – 40 to 80 respirations perminute

Infants – 30 respirations per minute

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Age 5 – 25 respirations per minute

Adults – 12 to 18 respirations perminute

Rate often increases somewhat with oldage