Mechanics of BreathingMechanics of Breathing

Introduction Introduction

Pulmonary ventilation:Pulmonary ventilation: Moving air into and out of the lungsMoving air into and out of the lungs BreathingBreathing

Inspiration = moving air into the lungsInspiration = moving air into the lungs Expiration = moving air out of lungsExpiration = moving air out of lungs

Pressure RelationshipsPressure Relationships

Intrapulmonary pressureIntrapulmonary pressure Pressure within the alveoli (lungs)Pressure within the alveoli (lungs) Changes with phases of breathingChanges with phases of breathing Always equalizes itself with atmospheric Always equalizes itself with atmospheric

pressurepressure Intrapleural pressureIntrapleural pressure

Pressure within intrapleural spacePressure within intrapleural space Always 4mmHg less than intrapulmonary Always 4mmHg less than intrapulmonary

pressurepressure

AtalectasisAtalectasis

Any conditions that causes intrapulmonary Any conditions that causes intrapulmonary pressure to equal intrapleural pressure will pressure to equal intrapleural pressure will cause the lungs to collapsecause the lungs to collapse This means they lose the ability to move air This means they lose the ability to move air

since there is NO more pressure differencesince there is NO more pressure difference pneumothorax – air in the intrapleural space pneumothorax – air in the intrapleural space

due to traumadue to trauma

AtelectasisAtelectasis

Pulmonary ventilationPulmonary ventilation

Question: Why does breathing happen?Question: Why does breathing happen? ONLY acceptable answer: Volume ONLY acceptable answer: Volume

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

InspirationInspiration

Main inspiratory musclesMain inspiratory muscles Diaphragm & external intercostalsDiaphragm & external intercostals

Thoracic dimensions change to increase Thoracic dimensions change to increase volume of thoracic cavity by 0.5 litersvolume of thoracic cavity by 0.5 liters

Intrapulmonary pressure drops 1-3 mmHg Intrapulmonary pressure drops 1-3 mmHg and air rushes info normal quiet inspirationand air rushes info normal quiet inspiration

A deep forced inspiration requires A deep forced inspiration requires activation of accessory musclesactivation of accessory muscles

ExpirationExpiration

A passive process dependent on natural A passive process dependent on natural lung elasticitylung elasticity

The lungs recoil, volume decreases, The lungs recoil, volume decreases, alveoli compress, intrapulmonary pressure alveoli compress, intrapulmonary pressure rises, gas outflows to equalize the rises, gas outflows to equalize the pressure with atmospheric pressurepressure with atmospheric pressure

Forced expiration requires contraction of Forced expiration requires contraction of muscles of the abdominal wallmuscles of the abdominal wall

Physical factors influencingPhysical factors influencing

Pulmonary ventilation can be influenced Pulmonary ventilation can be influenced by 4 physical factorsby 4 physical factors Respiratory passage resistanceRespiratory passage resistance Lung complianceLung compliance Lung elasticityLung elasticity Alveolar surface tension forcesAlveolar surface tension forces

Respiratory passage resistanceRespiratory passage resistance

Friction as air moves Friction as air moves through passagesthrough passages Smooth muscle Smooth muscle

bronchoconstriction bronchoconstriction and,and,

Local accumulations Local accumulations of mucus, infectious of mucus, infectious material, and tumors material, and tumors will cause the air flow will cause the air flow to be reducedto be reduced

Disorders such as Disorders such as asthmaasthma

Lung complianceLung compliance

The ease with which lungs can readily The ease with which lungs can readily expandexpand

Affected by the elasticity of the lungs and Affected by the elasticity of the lungs and the thoracic cagethe thoracic cage

Diminished by 3 main factors:Diminished by 3 main factors: FibrosisFibrosis of the lung tissue of the lung tissue Ossification and/or muscle paralysis impairs Ossification and/or muscle paralysis impairs

flexibility of the thoracic cageflexibility of the thoracic cage Blockage of the passagewaysBlockage of the passageways

Lung fibrosisLung fibrosis

Lung ElasticityLung Elasticity

Essential for normal expirationEssential for normal expiration EmphysemaEmphysema: tissue becomes less elastic : tissue becomes less elastic

and more fibrousand more fibrous Read ALL the imbalances and info about Read ALL the imbalances and info about

emphysema within your handoutemphysema within your handout

Page 415 in textPage 415 in text

Alveolar Surface Tension ForcesAlveolar Surface Tension Forces

Surface tension – molecules of liquid hold Surface tension – molecules of liquid hold together with hydrogen bondstogether with hydrogen bonds

Surfactant – substance which interferes Surfactant – substance which interferes with cohesion of water molecules so less with cohesion of water molecules so less energy is needed to expand the lungsenergy is needed to expand the lungs

IRDSIRDS – Infant Respiratory Distress – Infant Respiratory Distress Syndrome – read imbalanceSyndrome – read imbalance

Type II CellsType II Cells

End of Quiz #3 MaterialEnd of Quiz #3 Material

Gas Exchanges in the Gas Exchanges in the BodyBody

Gas Exchanges Gas Exchanges

Occur:Occur: Between Between the blood and the alveolithe blood and the alveoli AND AND Between Between the blood and the tissue cellsthe blood and the tissue cells Takes place by simple Takes place by simple diffusiondiffusion Depends on Depends on partial pressurespartial pressures of oxygen & of oxygen &

carbon dioxidecarbon dioxide That exist on opposite sides of the exchange That exist on opposite sides of the exchange

membranemembrane Diagrams on page 416-417 of textDiagrams on page 416-417 of text

Dalton’s LawDalton’s Law

Total pressure exerted by a mixture of Total pressure exerted by a mixture of gases is equal to the sum of the partial gases is equal to the sum of the partial pressures of each individual gaspressures of each individual gas

(Ptotal = P1 + P2 + P3 + …) (Ptotal = P1 + P2 + P3 + …) The partial pressure of each gas is directly The partial pressure of each gas is directly

proportional to its % in the mixtureproportional to its % in the mixture

N2: 78.08%, O2: 20.95%, CO2: 0.04%

Henry’s lawHenry’s law Each gas will dissolve in a liquid in Each gas will dissolve in a liquid in

proportion to its partial pressure and proportion to its partial pressure and solubility coefficient of the liquidsolubility coefficient of the liquid COCO22 = .57 = .57

OO22 = .024 = .024

NN22 = .012 = .012

Solubility increases with increasing partial Solubility increases with increasing partial pressurepressure

Solubility decreases with increasing Solubility decreases with increasing temperaturetemperature

Hyperbaric ConditionsHyperbaric Conditions

Hyperbaric Hyperbaric oxygen oxygen chambers – chambers – designed to designed to force greater force greater amounts of amounts of oxygen into oxygen into patient’s bloodpatient’s blood

Life ApplicationsLife Applications

Write down in detail the things we discuss!!!!Write down in detail the things we discuss!!!! Oxygen toxicityOxygen toxicity Nitrogen narcosisNitrogen narcosis Decompression sicknessDecompression sickness High altitude sicknessHigh altitude sickness

Now what would happen if you Now what would happen if you breathed 100 percent oxygen?breathed 100 percent oxygen?

Exposed to 100 percent oxygen at normal Exposed to 100 percent oxygen at normal air pressure for 48 hoursair pressure for 48 hours A highly reactive form of the oxygen A highly reactive form of the oxygen

molecule, called a free radical destroys molecule, called a free radical destroys proteins and membranes in the epithelial proteins and membranes in the epithelial cells. cells.

In humans breathing 100 percent oxygen at In humans breathing 100 percent oxygen at normal pressure, here's what happens:normal pressure, here's what happens:

Fluid accumulates in the Fluid accumulates in the lungslungs. . Gas exchange in the alveoli slows down so person Gas exchange in the alveoli slows down so person

has to breathe more to get enough oxygen. has to breathe more to get enough oxygen. Volume of exchangeable air decreases by 17 Volume of exchangeable air decreases by 17

percent. percent.

SCUBASCUBA In contrast, when 100 percent oxygen is breathed under In contrast, when 100 percent oxygen is breathed under

high pressure (more than four times that of atmospheric high pressure (more than four times that of atmospheric pressure), acute oxygen poisoning can occur with these pressure), acute oxygen poisoning can occur with these symptoms:symptoms: Nausea Nausea Dizziness Dizziness MuscleMuscle twitches twitches Blurred vision Blurred vision Seizures/convulsions Seizures/convulsions

Such high oxygen pressures can be experienced by Such high oxygen pressures can be experienced by military military SCUBASCUBA divers using rebreathing devices, divers divers using rebreathing devices, divers being treated for the bends in hyperbaric chambers or being treated for the bends in hyperbaric chambers or patients being treated for acute carbon monoxide patients being treated for acute carbon monoxide poisoning. These patients must be carefully monitored poisoning. These patients must be carefully monitored during treatment.during treatment.

Nitrogen NarcosisNitrogen Narcosis

As the total gas pressure increases with As the total gas pressure increases with increasing dive depth,increasing dive depth, the partial pressure of nitrogen increasesthe partial pressure of nitrogen increases more nitrogen becomes dissolved in the more nitrogen becomes dissolved in the

blood. blood. This high nitrogen concentration impairs the This high nitrogen concentration impairs the

conduction of nerve impulses and mimics the conduction of nerve impulses and mimics the effects of alcohol or narcotics.effects of alcohol or narcotics.

Symptoms of nitrogen narcosis Symptoms of nitrogen narcosis include:include:

WoozinessWooziness GiddinessGiddiness EuphoriaEuphoria DisorientationDisorientation loss of balanceloss of balance loss of manual loss of manual

dexteritydexterity

slowing of reaction slowing of reaction timetime

fixation of ideasfixation of ideas impairment of impairment of

complex reasoning. complex reasoning. These effects are These effects are

exacerbated by exacerbated by cold, stress, and a cold, stress, and a rapid rate of rapid rate of compression.compression.

Decompression Sickness (the Decompression Sickness (the bends)bends)

As pressure increases, solubility of gases As pressure increases, solubility of gases increaseincrease

Larger quantities of Nitrogen are forced Larger quantities of Nitrogen are forced into the body fluid/blood but not used by into the body fluid/blood but not used by the bodythe body

Ascending rapidly causes nitrogen gas to Ascending rapidly causes nitrogen gas to become less soluble and “bubble” out of become less soluble and “bubble” out of the blood too fast to be exhaledthe blood too fast to be exhaled

Decompression sicknessDecompression sickness

Gas collected in joint spaces and can also Gas collected in joint spaces and can also cause air embolisms which can lead to cause air embolisms which can lead to heart attack & strokeheart attack & stroke

Treatment:Treatment: Hyperbaric chamberHyperbaric chamber Take back down to depth & bring up slowlyTake back down to depth & bring up slowly

Internal & External Internal & External RespirationRespiration

Factors influencing internal & Factors influencing internal & external respirationexternal respiration

Partial pressure gradients and gas Partial pressure gradients and gas solubilities cont’solubilities cont’ Oxygen = has low solubility but steep partial Oxygen = has low solubility but steep partial

pressure gradient (104 mmHg in alveoli – 40 pressure gradient (104 mmHg in alveoli – 40 mmHg in blood = 64 mmHg pressure mmHg in blood = 64 mmHg pressure gradient)gradient)

Carbon dioxide = has solubility ~20x greater Carbon dioxide = has solubility ~20x greater than oxygen but partial pressure gradient is than oxygen but partial pressure gradient is only 5 mmHgonly 5 mmHg

Factors influencing internal & Factors influencing internal & external respirationexternal respiration

Partial pressure gradients and gas Partial pressure gradients and gas solubilitiessolubilities Due to the ratios of solubility coefficients and Due to the ratios of solubility coefficients and

pressure gradients:pressure gradients: ~Equal amounts of gases are exchanged~Equal amounts of gases are exchanged pH is not affectedpH is not affected

H2O + CO2 = H2CO3 (carbonic acid)H2O + CO2 = H2CO3 (carbonic acid)

Factors influencing internal & Factors influencing internal & external respirationexternal respiration

Thickness of respiratory membranesThickness of respiratory membranes 0.5 to 1.0 micrometers0.5 to 1.0 micrometers Hypoxia = oxygen deprivationHypoxia = oxygen deprivation Thickness – edematous (swollen) tissue can Thickness – edematous (swollen) tissue can

be caused by congestion and pneumoniabe caused by congestion and pneumonia Emphysema – infections can thicken Emphysema – infections can thicken

membranesmembranes

Factors influencing internal & Factors influencing internal & external respirationexternal respiration

Surface AreaSurface Area 70-80 square 70-80 square

meters for gas meters for gas exchangeexchange

EmphysemaEmphysemaWalls of alveoli Walls of alveoli

break downbreak downLess surface Less surface

area to volume area to volume ratioratio

Transport of respiratory Transport of respiratory gasesgases

Oxygen TransportOxygen Transport

Most oxygen is bound to hemoglobin for Most oxygen is bound to hemoglobin for transport (blood is cherry red)transport (blood is cherry red)

Vocabulary to understandVocabulary to understand Loading = binding oxygen to hemoglobin for Loading = binding oxygen to hemoglobin for

transporttransport Unloading = releasing oxygen from Unloading = releasing oxygen from

hemoglobin to go into tissue cellshemoglobin to go into tissue cells

http://ems.lchospital.com/education/respirahttp://ems.lchospital.com/education/respiration.htmtion.htm

http://www.stemnet.nf.ca/~dpower/resp/exhttp://www.stemnet.nf.ca/~dpower/resp/exchange.htmchange.htm

http://highered.mcgraw-hill.com/sites/0072http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/495855/student_view0/chapter25/

Factors affecting hemoglobin Factors affecting hemoglobin transporttransport

POPO22 Affects unloading rateAffects unloading rate 20-25% of oxygen unloaded to tissues in one 20-25% of oxygen unloaded to tissues in one

systemic circuitsystemic circuit Leaves a venous reserve of 75%Leaves a venous reserve of 75% This is why brain death will begin to occur 3-4 This is why brain death will begin to occur 3-4

minutes after your heart stopsminutes after your heart stops CPR must begin ASAP!!CPR must begin ASAP!!

Factors affecting hemoglobin Factors affecting hemoglobin transporttransport

As the temperature increases – oxygen As the temperature increases – oxygen unloading increasesunloading increases Hard working tissues = high metabolism rate = heat Hard working tissues = high metabolism rate = heat

produced = more oxygen unloadedproduced = more oxygen unloaded Hard working tissues need more oxygen to produce Hard working tissues need more oxygen to produce

more ATP = the heat is one way the tissues signal the more ATP = the heat is one way the tissues signal the body to bring more oxygenbody to bring more oxygen

Cold tissues = low metabolism = less oxygen Cold tissues = low metabolism = less oxygen unloadedunloaded

Nose & Cheeks are red when cold because the body Nose & Cheeks are red when cold because the body is trying to bring them a little more heat = no is trying to bring them a little more heat = no additional oxygen is unloaded in this caseadditional oxygen is unloaded in this case

Factors affecting hemoglobin Factors affecting hemoglobin transporttransport

Active tissues = made lots of ATP so lots of Active tissues = made lots of ATP so lots of carbon dioxide and hydrogen ions have been carbon dioxide and hydrogen ions have been produced as a waste product = acidosis = produced as a waste product = acidosis = increased oxygen unloadingincreased oxygen unloading COCO22 + H + H22O = HO = H22COCO33 (carbonic acid) (carbonic acid)

Know the types of hypoxia and the symptoms & Know the types of hypoxia and the symptoms & treatment of treatment of COCO (fix this in notes) poisoning – (fix this in notes) poisoning – see handoutsee handout

Also read the bracketed info on page 743 of Also read the bracketed info on page 743 of handouthandout

Carbon Monoxide poisoningCarbon Monoxide poisoning

Carbon dioxide transportCarbon dioxide transport

7% dissolved in plasma7% dissolved in plasma ~20% bound to hemoglobin – aka. ~20% bound to hemoglobin – aka.

CarbaminohemoglobinCarbaminohemoglobin 70% is in the form of the bicarbonate ion 70% is in the form of the bicarbonate ion

(HCO(HCO33--))

Carbonic acid and bicarbonate ion work Carbonic acid and bicarbonate ion work together as a buffer system to resists together as a buffer system to resists changes in pHchanges in pH

HypoventilationHypoventilation

Slow & shallow respirationSlow & shallow respiration Not adequate expiration soNot adequate expiration so

COCO22 is not vented out of the body is not vented out of the body

Production of excess acidProduction of excess acidHH22O + COO + CO22 = H = H22COCO33 (carbonic acid) (carbonic acid)

Respiratory acidosis resultsRespiratory acidosis results

HyperventilationHyperventilation

Deep & rapid respirationDeep & rapid respiration Too much COToo much CO22 is vented out of the body is vented out of the body Not enough acid productionNot enough acid production

HH22O + COO + CO22 = H = H22COCO33 (carbonic acid) (carbonic acid)

Respiratory alkalosis resultsRespiratory alkalosis results Treatment: trap the COTreatment: trap the CO22 and and

rebreathe it till breathing returns to rebreathe it till breathing returns to normalnormal

ImbalancesImbalancesPages 744-745 of handoutPages 744-745 of handout

Chronic BronchitisChronic Bronchitis

Symptoms: inflammation of mucosa – Symptoms: inflammation of mucosa – chronic mucus productionchronic mucus production Impairs ventilation and gas exchangeImpairs ventilation and gas exchange Reduction of airway diameterReduction of airway diameter

““blue bloater” – hypoxia leads to cyanosis blue bloater” – hypoxia leads to cyanosis – CO– CO22 retention leads to hyperinflation of retention leads to hyperinflation of

chest wallchest wall Causative factors: cigarette smokingCausative factors: cigarette smoking

NormalNormal

BronchitisBronchitis

Obstructive EmphysemaObstructive Emphysema

““pink puffer”pink puffer” Gas exchange adequate until end stage so Gas exchange adequate until end stage so

stay oxygenated and pinkstay oxygenated and pink Breathing is very labored due to lack of Breathing is very labored due to lack of

alveolar recoilalveolar recoil Barrel chest from hyperinflation of lungsBarrel chest from hyperinflation of lungs Alveolar walls collapse = loss of surface Alveolar walls collapse = loss of surface

areaarea Causative factor: cigarette smokingCausative factor: cigarette smoking

4 features in common4 features in common

Both emphysema and chronic bronchitis Both emphysema and chronic bronchitis have:have: Smoking historySmoking history Dyspnea = air hunger due to disfunctional Dyspnea = air hunger due to disfunctional

breathingbreathing Apnea = no breathingApnea = no breathing Eupnea = normal breathingEupnea = normal breathing

Coughing & pulmonary infectionsCoughing & pulmonary infections Will develop respiratory failure, hypoxia, Will develop respiratory failure, hypoxia,

acidosisacidosis

Lung CancerLung Cancer

Basic InfoBasic Info 1/3 of all cancer deaths are due to lung 1/3 of all cancer deaths are due to lung

cancerscancers 90% have a smoking history90% have a smoking history Metastasizes very rapidly due to vascularity of Metastasizes very rapidly due to vascularity of

lungslungs

3 types3 types

Know the descriptions of these 3 types of Know the descriptions of these 3 types of lung cancers from your handoutlung cancers from your handout Squamous cell carcinomaSquamous cell carcinoma AdenocarcinomaAdenocarcinoma Oat cell (small cell) carcinomaOat cell (small cell) carcinoma

Squamous cell carcinomaSquamous cell carcinoma

Adenocarcinoma Adenocarcinoma

Oat cell carcinomaOat cell carcinoma

TreatmentsTreatments

Resection of diseased portion of lungResection of diseased portion of lung Radiation therapyRadiation therapy Chemotherapy Chemotherapy

Lung ResectionLung Resection

Developmental AspectsDevelopmental Aspects

READ your handoutREAD your handout

Read through the Developmental Aspects Read through the Developmental Aspects section of your notes and your handoutsection of your notes and your handout

Know the related clinical terms on the Know the related clinical terms on the back page of your handoutback page of your handout

STUDYSTUDY