1 Chapter 16 Respiration • Functions of the respiratory system – – – – – – – Respiration • The term respiration includes 3 separate functions: • Ventilation: – Breathing. • Gas exchange: – Occurs between air and blood in the lungs. – Occurs between blood and tissues. •0 2 utilization: – Cellular respiration. Steps in Respiration Fig not in book Type I cell Type II cell Fig. 16.1 Organization of the respiratory system. Fig. 16.4 The conducting zone • Low -resistance pathway for airflow • Defends against yucky stuff • Warms and moistens air • When you have kids it enables you to yell at them. ϖ No gas exchange Fig. 16.5
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Chapter 16Respiration
• Functions of the respiratory system–––––––
Respiration• The term respiration includes 3 separate
functions:• Ventilation:
– Breathing.• Gas exchange:
– Occurs between air and blood in the lungs.– Occurs between blood and tissues.
• 02 utilization:– Cellular respiration.
Steps inRespiration
Fig notin book
Type I cell
Type II cell
Fig. 16.1
Organization of therespiratory system.
Fig. 16.4
The conducting zone• Low -resistance
pathway forairflow
• Defends againstyucky stuff
• Warms andmoistens air
• When you havekids it enablesyou to yell atthem.
ϖ No gas exchangeFig. 16.5
2
Respiratory Zone
• Region of gasexchange betweenair and blood.
• Includes respiratorybronchioles.
• Must containalveoli.
• Gas exchangeoccurs by diffusion.
Fig. 16.4Figure not in book
Fig. 16.8
Figure not in book
Ventilation and Lung MechanicsStep 1: Getting air into and out of lungs
• Remember: F = ΔP/R– F = flow– ΔP = pressure difference (mmHg)– R = resistance to flow.
Ventilation and Lung MechanicsStep 1: Getting air into and out of lungs
Fig not in book
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Fig not in book
Really, Really Important Point!
• During inspiration and expiration volume oflungs is made to change.
¬By Boyle’s law, these changes causechanges in alveolar pressure which drivesair into or out of lungs.
Volume of lungs depends on:
• Transpulmonary pressure - difference inpressure between outside and inside oflungs.
• Elasticity (stretchability) of lungs.
Surface Tension
• Law of Laplace:• Pressure in alveoli is
directly proportionalto surface tensionand inverselyproportional toradius of alveoli.
Fig. 16.11
Creating the Intrapleural Pressure
• Pull of lungs inward and chestwall outwardon intrapleural fluid causes a negativepressure within this space.
Fig. 16.15
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Fig not in bookFig not in book
Lung Compliance
• CL = magnitude of change in lung volume(ΔVL) produced by a given change intranspulmonary pressure.
• CL = ΔVL/Δ (Palv - Pip)• Greater the lung compliance the _______ it
is to expand the lungs at any giventranspulmonary pressure.
Fig not in book
Determinants of LungCompliance
• Stretchability• Surface tension at air-water interfaces
within alveoli.– Assets of surfactant.
Surfactant• Phospholipid
produced byalveolar type IIcells.
• Lowers surfacetension.
• Reduces attractiveforces of hydrogenbonding bybecominginterspersedbetween H20molecules.
• As alveoli radiusdecreases,surfactant’s abilityto lower surfacetension increases. Fig. 16.12
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Fig. 16.14 See also table 16.2
Pulmonary Function Tests
• Assessed by spirometry.• Subject breathes into a closed system in
which air is trapped within a bell floating inH20.
• The bell moves up when the subject exhalesand down when the subject inhales.
Schematic of aspirometer (left)and the spirometeryou will be using in lab (above).
Spirogram
• Tidal volume:Amount of air expired with each breath.• Vital capacity:The maximum amount of air that can be forcefully exhaled
after maximum inhalation.
Fig. 16.16
Table 16.3 Terms Used to Describe Lung Volumes andCapacities
Term DefinitionLung Volumes The four nonoverlapping components of the total lung
capacity
Tidal volume The volume of gas inspired or expired in an unforcedrespiratory cycle
Inspiratory reserve volume The maximum volume of gas that can be inspired duringforced breathing in addition to tidal volume
Expiratory reserve volume The maximum volume of gas that can be expired duringforced breathing in addition to tidal volume
Residual volume The volume of gas remaining in the lungs after a maximumexpiration
Lung Capacities Measurements that are the sum of two or more lungvolumes
Total lung capacity The total amount of gas in the lungs after a maximuminspiration
Vital capacity The maximum amount of gas that can be expired after amaximum inspiration
Inspiratory capacity The maximum amount of gas that can be inspired after anormal tidal expiration
Functional residual capacity The amount of gas remaining in the lungs after a normaltidal expiration
Figure not in book
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Anatomical Dead Space
• Not all of the inspired air reaches the alveoli.• As fresh air is inhaled it is mixed with anatomical
dead space.• Conducting zone and alveoli where 02
concentration is lower than normal and C02concentration is higher than normal.
• Alveolar ventilation: F x (TV- DS)– F = frequency (breaths/min.).– TV = tidal volume.– DS = dead space.
Airway resistance andrestrictive vs. obstructive disorders
• Recall:• F = (Patm - Palv) / R• Resistance depends on:
–––
Airway Radii and Resistance
• Airway radii affected by– Physical factors
• “going down the wrong pipe”• Asthma caused by chemical factors (see below).
– Neural factors• Epinephrine
– Chemical factors• CIGARETTE SMOKE, pollutants, viruses allergens,
bronchoconstrictor chemicals
Restrictive and ObstructiveDisorders
• Restrictivedisorder:– Vital capacity is
reduced.– FVC is normal.
• Obstructivedisorder:– VC is normal.– FEV1 is reduced.
Fig. 16.17
Gas Exchange• Dalton’s Law:• Total pressure of a gas mixture is = to the
sum of the pressures that each gas in themixture would exert independently.