RespirationRespiration
VentilationVentilation: Movement of air into : Movement of air into and out of lungsand out of lungs
External respirationExternal respiration: Gas exchange : Gas exchange between air in lungs and bloodbetween air in lungs and blood
Transport of oxygen and carbon Transport of oxygen and carbon dioxide in the blooddioxide in the blood
Internal respirationInternal respiration: Gas exchange : Gas exchange between the blood and tissuesbetween the blood and tissues
Respiratory System Respiratory System Functions Functions
Gas exchangeGas exchange: Oxygen enters blood and : Oxygen enters blood and carbon dioxide leavescarbon dioxide leaves
Regulation of blood pHRegulation of blood pH: Altered by : Altered by changing blood carbon dioxide levelschanging blood carbon dioxide levels
Voice productionVoice production: Movement of air past : Movement of air past vocal folds makes sound and speechvocal folds makes sound and speech
OlfactionOlfaction: Smell occurs when airborne : Smell occurs when airborne molecules drawn into nasal cavitymolecules drawn into nasal cavity
ProtectionProtection: Against microorganisms by : Against microorganisms by preventing entry and removing thempreventing entry and removing them
Respiratory System Respiratory System DivisionsDivisions
Upper tractUpper tract Nose, pharynx Nose, pharynx
and associated and associated structuresstructures
Lower tractLower tract Larynx, Larynx,
trachea, trachea, bronchi, lungsbronchi, lungs
Nose and PharynxNose and Pharynx
NoseNose External noseExternal nose Nasal cavityNasal cavity
FunctionsFunctions Passageway for airPassageway for air Cleans the airCleans the air Humidifies, warms Humidifies, warms
airair SmellSmell Along with paranasal Along with paranasal
sinuses are sinuses are resonating chambers resonating chambers for speechfor speech
PharynxPharynx Common opening Common opening
for digestive and for digestive and respiratory systemsrespiratory systems
Three regionsThree regions NasopharynxNasopharynx OropharynxOropharynx LaryngopharynxLaryngopharynx
LarynxLarynx
FunctionsFunctions Maintain an open passageway for air movementMaintain an open passageway for air movement Epiglottis and vestibular folds prevent swallowed Epiglottis and vestibular folds prevent swallowed
material from moving into larynxmaterial from moving into larynx Vocal folds are primary source of sound productionVocal folds are primary source of sound production
TracheaTrachea
WindpipeWindpipe Divides Divides
to formto form Primary Primary
bronchibronchi CarinaCarina: :
Cough Cough reflexreflex
Tracheobronchial TreeTracheobronchial Tree
Conducting zoneConducting zone Trachea to terminal bronchioles Trachea to terminal bronchioles
which is ciliated for removal of debriswhich is ciliated for removal of debris Passageway for air movementPassageway for air movement Cartilage holds tube system open and Cartilage holds tube system open and
smooth muscle controls tube diametersmooth muscle controls tube diameter Respiratory zoneRespiratory zone
Respiratory bronchioles to alveoliRespiratory bronchioles to alveoli Site for gas exchangeSite for gas exchange
Fig. 4. Effects of Fig. 4. Effects of methacholine on depth of methacholine on depth of airwayairway
surface liquid. surface liquid. aa: control : control tissue not exposed to tissue not exposed to methacholine.methacholine.
bb: 2-min methacholine : 2-min methacholine exposure. Putativeexposure. Putative
sol and mucous gel are sol and mucous gel are clearly visible. clearly visible. cc: 30-min: 30-min
exposure. Tissues were exposure. Tissues were radiant etched for 20 s to radiant etched for 20 s to 11
min. Scale bar 5 20 μm.min. Scale bar 5 20 μm.
From From Am. J. Physiol. Am. J. Physiol. 274 274 ((Lung Cell. Mol. Physiol. Lung Cell. Mol. Physiol. 18): L388–L395, 1998.—18): L388–L395, 1998.—
LungsLungs
Two lungsTwo lungs: Principal organs of respiration: Principal organs of respiration Right lungRight lung: Three lobes: Three lobes Left lungLeft lung: Two lobes: Two lobes
DivisionsDivisions Lobes, bronchopulmonary segments, lobulesLobes, bronchopulmonary segments, lobules
PleuraPleura
Pleural fluid produced by pleural Pleural fluid produced by pleural membranesmembranes Acts as lubricantActs as lubricant Helps hold parietal and visceral pleural Helps hold parietal and visceral pleural
membranes togethermembranes together
VentilationVentilation
Movement of air into and out of Movement of air into and out of lungslungs
Air moves from area of higher Air moves from area of higher pressure to area of lower pressurepressure to area of lower pressure
Pressure is inversely related to Pressure is inversely related to volumevolume
Changing Alveolar Changing Alveolar VolumeVolume
Lung recoilLung recoil Causes alveoli to collapse resulting from Causes alveoli to collapse resulting from
Elastic recoil and surface tensionElastic recoil and surface tension Surfactant: Reduces tendency of lungs to Surfactant: Reduces tendency of lungs to
collapsecollapse
Pleural pressurePleural pressure Negative pressure can cause alveoli to Negative pressure can cause alveoli to
expandexpand Pneumothorax is an opening between Pneumothorax is an opening between
pleural cavity and air that causes a loss pleural cavity and air that causes a loss of pleural pressureof pleural pressure
ComplianceCompliance
Measure of the ease with which lungs Measure of the ease with which lungs and thorax expandand thorax expand The greater the compliance, the easier it The greater the compliance, the easier it
is for a change in pressure to cause is for a change in pressure to cause expansionexpansion
A lower-than-normal compliance means A lower-than-normal compliance means the lungs and thorax are harder to expandthe lungs and thorax are harder to expand Conditions that decrease complianceConditions that decrease compliance
Pulmonary fibrosisPulmonary fibrosis Pulmonary edemaPulmonary edema Respiratory distress syndrome Respiratory distress syndrome
Pulmonary VolumesPulmonary Volumes Tidal volumeTidal volume
Volume of air inspired or expired during a normal Volume of air inspired or expired during a normal inspiration or expirationinspiration or expiration
Inspiratory reserve volumeInspiratory reserve volume Amount of air inspired forcefully after inspiration of Amount of air inspired forcefully after inspiration of
normal tidal volumenormal tidal volume
Expiratory reserve volumeExpiratory reserve volume Amount of air forcefully expired after expiration of Amount of air forcefully expired after expiration of
normal tidal volumenormal tidal volume
Residual volumeResidual volume Volume of air remaining in respiratory passages and Volume of air remaining in respiratory passages and
lungs after the most forceful expirationlungs after the most forceful expiration
Pulmonary CapacitiesPulmonary Capacities
Inspiratory capacityInspiratory capacity Tidal volume plus inspiratory reserve volumeTidal volume plus inspiratory reserve volume
Functional residual capacityFunctional residual capacity Expiratory reserve volume plus the residual volumeExpiratory reserve volume plus the residual volume
Vital capacityVital capacity Sum of inspiratory reserve volume, tidal volume, Sum of inspiratory reserve volume, tidal volume,
and expiratory reserve volumeand expiratory reserve volume
Total lung capacityTotal lung capacity Sum of inspiratory and expiratory reserve volumes Sum of inspiratory and expiratory reserve volumes
plus the tidal volume and residual volumeplus the tidal volume and residual volume
Minute and Alveolar Minute and Alveolar VentilationVentilation
Minute ventilationMinute ventilation: Total amount of air : Total amount of air moved into and out of respiratory system moved into and out of respiratory system per minuteper minute
Respiratory rate or frequencyRespiratory rate or frequency: Number of : Number of breaths taken per minutebreaths taken per minute
Anatomic dead spaceAnatomic dead space: Part of respiratory : Part of respiratory system where gas exchange does not take system where gas exchange does not take placeplace
Alveolar ventilationAlveolar ventilation: How much air per : How much air per minute enters the parts of the respiratory minute enters the parts of the respiratory system in which gas exchange takes placesystem in which gas exchange takes place
Physical Principles of Physical Principles of Gas ExchangeGas Exchange
Partial pressurePartial pressure The pressure exerted by each type of gas in The pressure exerted by each type of gas in
a mixturea mixture Dalton’s lawDalton’s law Water vapor pressureWater vapor pressure
Diffusion of gases through liquidsDiffusion of gases through liquids Concentration of a gas in a liquid is Concentration of a gas in a liquid is
determined by its partial pressure and its determined by its partial pressure and its solubility coefficientsolubility coefficient
Henry’s lawHenry’s law
Physical Principles of Physical Principles of Gas ExchangeGas Exchange
Diffusion of gases through the Diffusion of gases through the respiratory membranerespiratory membrane Depends on membrane’s thickness, the Depends on membrane’s thickness, the
diffusion coefficient of gas, surface areas of diffusion coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli membrane, partial pressure of gases in alveoli and bloodand blood
Relationship between ventilation Relationship between ventilation and pulmonary capillary flowand pulmonary capillary flow Increased ventilation or increased pulmonary Increased ventilation or increased pulmonary
capillary blood flow increases gas exchangecapillary blood flow increases gas exchange Physiologic shunt is deoxygenated blood Physiologic shunt is deoxygenated blood
returning from lungsreturning from lungs
Oxygen and Carbon Oxygen and Carbon Dioxide Dioxide
Diffusion GradientsDiffusion Gradients OxygenOxygen
Moves from alveoli Moves from alveoli into blood. Blood is into blood. Blood is almost completely almost completely saturated with oxygen saturated with oxygen when it leaves the when it leaves the capillarycapillary
P0P022 in blood decreases in blood decreases because of mixing because of mixing with deoxygenated with deoxygenated bloodblood
Oxygen moves from Oxygen moves from tissue capillaries into tissue capillaries into the tissuesthe tissues
Carbon dioxideCarbon dioxide Moves from Moves from
tissues into tissue tissues into tissue capillariescapillaries
Moves from Moves from pulmonary pulmonary capillaries into capillaries into the alveolithe alveoli
Hemoglobin and Oxygen Hemoglobin and Oxygen TransportTransport
Oxygen is transported by hemoglobin (98.5%) Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%)and is dissolved in plasma (1.5%)
Oxygen-hemoglobin dissociation curve shows Oxygen-hemoglobin dissociation curve shows that hemoglobin is almost completely that hemoglobin is almost completely saturated when P0saturated when P022 is 80 mm Hg or above. is 80 mm Hg or above. At lower partial pressures, the hemoglobin At lower partial pressures, the hemoglobin releases oxygen.releases oxygen.
A shift of the curve to the left because of an A shift of the curve to the left because of an increase in pH, a decrease in carbon dioxide, increase in pH, a decrease in carbon dioxide, or a decrease in temperature results in an or a decrease in temperature results in an increase in the ability of hemoglobin to hold increase in the ability of hemoglobin to hold oxygenoxygen
Hemoglobin and Hemoglobin and Oxygen TransportOxygen Transport
A shift of the curve to the right because of A shift of the curve to the right because of a decrease in pH, an increase in carbon a decrease in pH, an increase in carbon dioxide, or an increase in temperature dioxide, or an increase in temperature results in a decrease in the ability of results in a decrease in the ability of hemoglobin to hold oxygenhemoglobin to hold oxygen
The substance 2.3-bisphosphoglycerate The substance 2.3-bisphosphoglycerate increases the ability of hemoglobin to increases the ability of hemoglobin to release oxygenrelease oxygen
Fetal hemoglobin has a higher affinity for Fetal hemoglobin has a higher affinity for oxygen than does maternaloxygen than does maternal
Transport of Carbon Transport of Carbon DioxideDioxide
Carbon dioxide is transported as Carbon dioxide is transported as bicarbonate ions (70%) in combination with bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with blood proteins (23%) and in solution with plasma (7%)plasma (7%)
Hemoglobin that has released oxygen binds Hemoglobin that has released oxygen binds more readily to carbon dioxide than more readily to carbon dioxide than hemoglobin that has oxygen bound to it hemoglobin that has oxygen bound to it (Haldane effect)(Haldane effect)
In tissue capillaries, carbon dioxide In tissue capillaries, carbon dioxide combines with water inside RBCs to form combines with water inside RBCs to form carbonic acid which dissociates to form carbonic acid which dissociates to form bicarbonate ions and hydrogen ionsbicarbonate ions and hydrogen ions
Transport of Carbon Transport of Carbon DioxideDioxide
In lung capillaries, bicarbonate ions and In lung capillaries, bicarbonate ions and hydrogen ions move into RBCs and chloride hydrogen ions move into RBCs and chloride ions move out. Bicarbonate ions combine ions move out. Bicarbonate ions combine with hydrogen ions to form carbonic acid. with hydrogen ions to form carbonic acid. The carbonic acid is converted to carbon The carbonic acid is converted to carbon dioxide and water. The carbon dioxide dioxide and water. The carbon dioxide diffuses out of the RBCs.diffuses out of the RBCs.
Increased plasma carbon dioxide lowers Increased plasma carbon dioxide lowers blood pH. The respiratory system regulates blood pH. The respiratory system regulates blood pH by regulating plasma carbon blood pH by regulating plasma carbon dioxide levelsdioxide levels
Respiratory Areas in Respiratory Areas in BrainstemBrainstem
Medullary respiratory centerMedullary respiratory center Dorsal groups stimulate the diaphragmDorsal groups stimulate the diaphragm Ventral groups stimulate the intercostal Ventral groups stimulate the intercostal
and abdominal musclesand abdominal muscles Pontine (pneumotaxic) respiratory Pontine (pneumotaxic) respiratory
groupgroup Involved with switching between Involved with switching between
inspiration and expirationinspiration and expiration
Rhythmic VentilationRhythmic Ventilation Starting inspirationStarting inspiration
Medullary respiratory center neurons are continuously Medullary respiratory center neurons are continuously activeactive
Center receives stimulation from receptors and simulation Center receives stimulation from receptors and simulation from parts of brain concerned with voluntary respiratory from parts of brain concerned with voluntary respiratory movements and emotionmovements and emotion
Combined input from all sources causes action potentials Combined input from all sources causes action potentials to stimulate respiratory musclesto stimulate respiratory muscles
Increasing inspirationIncreasing inspiration More and more neurons are activatedMore and more neurons are activated
Stopping inspirationStopping inspiration Neurons stimulating also responsible for stopping Neurons stimulating also responsible for stopping
inspiration and receive input from pontine group and inspiration and receive input from pontine group and stretch receptors in lungs. Inhibitory neurons activated stretch receptors in lungs. Inhibitory neurons activated and relaxation of respiratory muscles results in expiration.and relaxation of respiratory muscles results in expiration.
Modification of Modification of VentilationVentilation
Cerebral and Cerebral and limbic systemlimbic system Respiration can Respiration can
be voluntarily be voluntarily controlled and controlled and modified by modified by emotionsemotions
Chemical controlChemical control Carbon dioxide is Carbon dioxide is
major regulatormajor regulator Increase or decrease Increase or decrease
in pH can stimulate in pH can stimulate chemo- sensitive area, chemo- sensitive area, causing a greater rate causing a greater rate and depth of and depth of respirationrespiration
Oxygen levels in Oxygen levels in blood affect blood affect respiration when a respiration when a 50%50% or greater or greater decrease from decrease from normal levels existsnormal levels exists
Herring-Breuer ReflexHerring-Breuer Reflex
Limits the degree of inspiration and Limits the degree of inspiration and prevents overinflation of the lungsprevents overinflation of the lungs InfantsInfants
Reflex plays a role in regulating basic Reflex plays a role in regulating basic rhythm of breathing and preventing rhythm of breathing and preventing overinflation of lungsoverinflation of lungs
AdultsAdults Reflex important only when tidal volume Reflex important only when tidal volume
large as in exerciselarge as in exercise
Ventilation in ExerciseVentilation in Exercise Ventilation increases abruptlyVentilation increases abruptly
At onset of exerciseAt onset of exercise Movement of limbs has strong influenceMovement of limbs has strong influence Learned componentLearned component
Ventilation increases graduallyVentilation increases gradually After immediate increase, gradual increase After immediate increase, gradual increase
occurs (4-6 minutes)occurs (4-6 minutes) Anaerobic threshold is highest level of Anaerobic threshold is highest level of
exercise without causing significant exercise without causing significant change in blood pHchange in blood pH If exceeded, lactic acid produced by skeletal If exceeded, lactic acid produced by skeletal
musclesmuscles
Effects of AgingEffects of Aging
Vital capacity and maximum minute Vital capacity and maximum minute ventilation decreaseventilation decrease
Residual volume and dead space Residual volume and dead space increaseincrease
Ability to remove mucus from Ability to remove mucus from respiratory passageways decreasesrespiratory passageways decreases
Gas exchange across respiratory Gas exchange across respiratory membrane is reducedmembrane is reduced
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