RESPIRATORY SYSTEM BREATHING MECHANISM AND LUNG VOLUMES & CAPACITIES

RESPIRATORY RESPIRATORY SYSTEMSYSTEM

BREATHING MECHANISM BREATHING MECHANISM ANDAND

LUNG VOLUMES & LUNG VOLUMES & CAPACITIESCAPACITIES

INSPIRATIONINSPIRATION

Passive Passive atmospheric pressure atmospheric pressure compared to intraalveolar pressurecompared to intraalveolar pressure– 760 mmHg – atm. Pressure760 mmHg – atm. Pressure– Diapragm contracts – moves downwardDiapragm contracts – moves downward

Increase volume: decrease pressureIncrease volume: decrease pressure Air moves inAir moves in

– Added Muscles: external intercostal, Added Muscles: external intercostal, sternocleidomastoid, pectoralis minorsternocleidomastoid, pectoralis minor

– surface tension of parietal and visceral surface tension of parietal and visceral pleural membranespleural membranes

– ComplianceCompliance

PRESSURESOF INSPIRATION

EXPIRATIONEXPIRATION

Elastic Recoil – Elastic Recoil – passive processpassive process

Decrease volume: Decrease volume: increase pressureincrease pressure– Air moves outAir moves out

Added force: internal Added force: internal intercostal + intercostal + abdominal musclesabdominal muscles

Non Respiratory Air Non Respiratory Air MovementsMovements– Cough, sneeze, laugh, Cough, sneeze, laugh,

cry, hiccup, yawn, cry, hiccup, yawn, speechspeech

LUNG VOLUMES AND LUNG VOLUMES AND CAPACITIESCAPACITIES

Tidal volume (TV) – Tidal volume (TV) – normal inhale/exhalenormal inhale/exhale

Inspiratory Reserve Inspiratory Reserve Volume (IRV) – max inhale Volume (IRV) – max inhale after normalafter normal

Expiratory Reserve Expiratory Reserve Volume (ERV) – max Volume (ERV) – max exhale after normal exhaleexhale after normal exhale

Residual Volume (RV) – Residual Volume (RV) – amount left in lungs after amount left in lungs after max. exhalemax. exhale

Vital Capacity – total Vital Capacity – total volume of max inhale to volume of max inhale to max exhalemax exhale– IRV + TV + ERVIRV + TV + ERV

Inspiratory Capacity – Inspiratory Capacity – Max. inhaleMax. inhale– IRV + TVIRV + TV

Functional Residual Functional Residual Capacity – amount left in Capacity – amount left in lungs after normal exhalelungs after normal exhale– ERV + RVERV + RV

Total Lung Capacity – max Total Lung Capacity – max amount of gas in lungsamount of gas in lungs– IRV + TV + ERV + RVIRV + TV + ERV + RV

GRAPH

CONTROL OF BREATHINGCONTROL OF BREATHING Rhythmic, involuntaryRhythmic, involuntary Respiratory center – medulla oblongata + ponsRespiratory center – medulla oblongata + pons

– Medullary rhythmicity centerMedullary rhythmicity center Dorsal: rhythmDorsal: rhythm Ventral: forceful breathsVentral: forceful breaths

– Pneumotaxic areaPneumotaxic area Rate of breathingRate of breathing

Factors affecting breathingFactors affecting breathing– CO2 and H+ ionsCO2 and H+ ions– Low O2Low O2– Hering-Bruer ReflexHering-Bruer Reflex– Emotional upsetEmotional upset– Hyperventilation and Holding BreathHyperventilation and Holding Breath

FACTORS

PRESSURES OF INSPIRATIONPRESSURES OF INSPIRATION

FACTORS AFFECTINGFACTORS AFFECTINGBREATHRATEBREATHRATE

Lung Volumes and CapacitiesLung Volumes and Capacities