Physiology of Respiratory System Flashcards
Respiration
exchange of gas between organism and environment
Inspiration
-bring air in lungs
-inhalation
Expiration
-moving air out of lungs
-exhalation
Pressure
-force over area
-P = F/A
-Increase force: increase pressure
-increase area: decrease pressure
Boyles Law
-pressure varies inversely w/volume for a given gas
-P1V1=P2V2
-volume increase, pressure decreases
-when piston pushed down: molecules closer together, molecular forces of repulsion increase pressure
-pressure increases
Lungs Have Volume
-increase volume, decrease pressure
-decrease in pressure causes air to enter the lungs
Rib Cage and Diaphragm
-Thoracic volume changes for inspiration
-2 planes of movement during inspiration
Planes of Movement For Inspiration
-vertical: up and down, from contraction of diaphragm
-transverse: horizontal, from elevation of rib cage
Lateral View Diaphragm
-When thorax expands transverse dimension thoracic cavity increase in volume
-when diaphragm contracts: thorax expands in vertical dimension, thoracic volume increases
Goal of Respiration
-oxygenate blood
-eliminate carbon dioxide
Gas Exchange Stages
-Ventilation
-Distribution
-Perfusion
-Diffusion
Ventilation
-actual air movement in respiratory pathway
-direct result of diaphragm and respiratory muscles
Distribution
-air circulated to 300-480 million alveoli
Perfusion
-migration through barrier
-oxygen poor blood from pulmonary artery to 6 billion capillaries supplying alveoli
Diffusion
actual gas exchange across alveolar-capillary membrane
Breathing Cycles
-1 cycle = 1 inspiration and 1 expiration
-known as tidal respiration
-entire cycle takes around 10 seconds: 4 inspiration, 6 expiration,
Tidal Volume
-air volume exchanged 1 respiratory cycle
-males and females: vary based on body and thorax size
-young adult female at rest: TV= 450cc
-young adult male at rest: TV= 600cc
-avg at rest: TV= 525cc
-during heavy work: as high as 2300cc
Inspiratory Reserve
-quantity of air can be inhaled beyond inhaled during tidal volume cycle
-male: 3000cc
-female: 1950cc
-avg: 2475cc
Expiratory reserve
-amount of air that can be pushed out of lungs beyond tidal volume
-male: 1200cc
-female: 800cc
-avg: 1000cc
Residual Volume
-air volume remaining in lungs after maximum exhalation
-includes dead air
-male: 1200cc
-female: 1000cc
-avg: 1100cc
Dead Air
-air volume in passageway not part of gas exchange
-remains in nasal, laryngeal, tracheal, bronchi, bronchioles
-component of residual volume
-100-200cc
Inspiratory Capacity
-max volume of air can be inhaled from resting expiratory level
-tidal volume + inspiratory reserve volume
-TV= 525cc
- IRV= 2475cc
-IC= 3000cc
Vital Capacity
-Quantity of air that can be exhaled after as deep of an inhalation as possible
-most frequently cites capacity
-VC= TV + IRV+ ERV
-VC= 4000cc, 4 liters
Vitalo Capacity Varies by Age
-Decreases with age starting about 20 years
-lower for females than males
Postural Effects on Vital Capacity
-reflects effects of gravity on viscera
-standing most efficient posture
-reclining posture reduced 20%
-head lower than feet less efficient
Total Lung Capacity
-Quantity of air lungs are capable holding height of max inhalation
-TLC = residual + tidal + IRV + ERV
-TLC = 5100cc
Volumes, Capacities, and Development
-vital capacity
-increases 20 mL per year until 20
-begins decline about 25 years of age
Capacities Change
-All except RV decline starting 25 years of age
-lung compliance increases due to elasticity loss: lung ability to be distended (bulge out)
-RV increase due to inability to fully inflate lungs (not as flexible)
Respiratory Rate
-conducting airway grows during development
-thorax grows more than lungs: lungs stretched to fill space
-infant resp rate: 40-70 bpm
-by 5 yrs: 20 bpm
-by 15 yrs: 18bpm
Pressures of Respiration
-inspiratory musculature increases thorax volume in 2 dimensions
-diaphragm contraction increases vertical dimension
-accessory muscles of inspiration increase transverse dimension
Atmospheric Pressure
-pressure arising from force of gravity on air molecules of atmosphere
Interoral Pressure
-pressure in mouth
Subglottal Pressure
-pressure below level of vocal folds (trachea)
Interoral and Subglottal Pressure equal when
vocal folds are abducted
Pulmonic or Alveolar Pressure
pressure within individual alveoli
Intrapleural or Pleural Pressure
pressure between visceral (lungs) and costal (rib) pleura
System at Rest
-Respiratory passage unrestricted
-atmospheric=intraoral=alveolar
-pleural surface (intrapleural) pressure = -3 to -5cm H2O
-creates suction for lungs to stay inflated
Diaphragm Contraction for Inspiration
-space between pleura increases: intrapleural pressure becomes more negative, up to -10cm H20
-expands each alveolus
-alveolar, subglottal, intraoral pressure becomes negative re: atmospheric, -2cmH20
-air enters lungs
System During Inspiration
-Neg pressure: intraoral, subglottal
Pressure After Inspiration
-Intraoral pressure
-slightly neg to atmospheric pressure
-due oral cavity expansion during inhalation process
-draws air into lungs during process
-Subglottal pressure
-higher than atmospheric pressure due to filled lungs
-alveolar pressure: equal to atmospheric pressure
Quiet Inspiration
-diaphragm and external intercostals contract
-compresses abdominal viscera: abdomen bulges out
Forced Inspiration
-diaphragm contracts more: abdomen protrudes
-thorax expands and elevates compresses abdominal viscera
Diaphragm Relaxes for Expiration
-thoracic space decreases
-intrapleural pressure becomes less negative
-alveolar pressure becomes positive relative +2 cm H2O
-subglottal and intraoral pressure become positive re. atmosphere
-air leaves lungs
During Expiration
-positive pressure
-intraoral
-subglottal
Intrapleural Pressure
-always negative: -6cm H20
-lungs constant expansion
-thorax grater in size than lungs
-lungs never completely deflate due to residual volume
Pressure of the Tissues
-relaxation pressure
-inspiratory pressure
-expiratory pressure
Inspiration Tissue Forces
-exerting forces overcome gravity and elastic forces of tissues: requires muscle action to overcome
-inspiration muscles contract: stretch tissues due to elasticity, abdomen distends, gravity returns tissue to resting state
Expiration Tissue Forces
-expiration capitalizes on gravity and elastic forces of tissues
-expiration muscles relax: stretch tissues return original dimensions due to elastic nature, gravity depresses rib cage
Relaxation Pressure Curves
-generated result of relaxing muscular contraction
-pressure varies w/degree of contraction
-more inspiration: greater positive pressure generated
-expressed as percentage of vital capacity
At Rest
-Lungs at 38% vital capacity
-RLV alveolar pressure = 0cm H20
-can exhale 38% of vital capacity
-can inhale 62% of vital capacity
Contributions to Relaxation Curve: chest wall
-accounts for curve in negative region
-below 55% VC thorax recoils outward
Contributions to Relaxation Curve: lung elasticity (distention)
-accounts for most of positive portion of curve
-about 55% VC lungs recoil inward
Contributions to Relaxation Curve: above 38% VC
-inspiratory process active
-expiratory process passive
Contributions to Relaxation Curve: below 38% VC
-expiratory process active
-inspiratory process passive
Summary Passive Forces
-relaxation pressure curve reflects pressures generated by restoring forces of tissue
Summary Passive Forces: above 38% vital capacity
-restoring forces generate positive pressure
-attempting to make thorax smaller
-chest wall accounts most neg pressure gnereated
Summary Passive Forces: below 38% vital capacity
-restoring forces generate neg pressure
-attempting to make thorax larger
-lung elasticity accounts most pos pressure generated
Inspiration Muscles best with
-completely deflated lungs
-expiratory muscles no good
Expiration Muscles best with
-completely inflated lungs
-inspiratory muscles no good
Respiration Changes in Adulthood
-see gradual changes in lung function
-by 20 yrs: elastic recoil starts declining
-bronchiole diameter begins increasing
-alveolar wall begins thickening
