ALTERATIONS IN OXYGENATION
Alveoli - Functional unit of lung interconnected by pores of Kohn that produce surfactant;
Each adult has 300 million alveoli arranged in clusters which are surrounded by capillary bed
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ALTERATIONS IN OXYGENATION
Alveoli - Functional unit of lung interconnected by pores of Kohn that produce surfactant;
Each adult has 300 million alveoli arranged in clusters which are surrounded by capillary bed
Gas exchange occurs via diffusion and depends on ventilation-perfusion ratio
Normal –fully-functional alveoli & good blood supply allow for maximum gas exchange
Impaired Gas exchange:
Alveoli is constricted, blocked or collapsed; blood passes alveoli without max gas exch.
Blood supply is blocked not giving alveoli adequate blood supply
Lung Tissue Properties:
Compliance – Expandability of lung which depends on surface tissue of alveoli & connective tissue of lungs →
elastin gives lungs stretchability
Normal – easily stretched when take a deep breath
Low – stiff/difficult to inflate → pulmonary fibrosis or morbid obesity
High – lungs lost elasticity (overdistended) → returning CO2 such as with emphysema r/t loss of some
alveolar wall→ lose recoil → overinflation
Elastic Recoil – ability of lungs to reduce in volume after being stretched
Respiratory Defense Mechanisms –
Filtration of air
Mucocilliary Clearance
Cough reflex
Reflex Bronchoconstriction
Alveolar Macrophages
Respiratory System Age Related Changes - respiratory peak @ age 25
Lifetime exposure to environmental stimuli – pollution; occupational hazards
Concurrent chronic disease – CAD, CHF, DM, COPD, alcoholism
Structural alterations – decr ability to take a deep breath; diminished vital capacity ( max amt of air inhaled &
exhaled in a cycle)
◦ ↓ in elastic recoil
◦ ↓ in chest wall compliance
◦ AP diameter increases
◦ Kyphoscoliosis with advancing age
◦ Alveolar surface decreases
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