Respiratory System: Gas Laws, Pulmonary Pressures-Lecture 22 Exam 4 Flashcards
(14 cards)
Alveoli
-Make up most of the lung
-Thin-walled hollow sacs
-Site of pulmonary gas exchange
-Surrounded by pulmonary
capillaries
Type I Alveolar Cells
-Form walls of the alveoli
-Permit O2 & CO2 gas exchange by diffusion
Type II Alveolar Cells
Secrete surfactant that decreases surface tension created by water to prevent lungs from collapsing
Respiratory Membrane
Area where gas exchange occurs between the respiratory &
cardiovascular systems
Respiratory Membrane Components
-Type 1 Alveolar Cells
-Pulmonary Capillary Cells
Gas Laws
- Dalton’s Law
- Gases move down a pressure gradient (high to low pressure)
- Boyle’s Law
Dalton’s Law
Atmospheric pressure is the sum of the partial pressures (P) of each individual gas
-P air=P N2 +P O2 +P Ar +P CO2 =760mmHg
Boyle’s Law
-If the volume of a container of gas changes, the pressure of the gases will change in an inverse manner
Atmospheric Pressure (Patm)
Pressure exerted by the air surrounding the body
Alveolar Pressure (Palv)
–Pressure in the alveoli
–Equalizes with atmospheric pressure (0 mm Hg)
–Fluctuates with breathing
-Decreases during inspiration (-1 mm Hg)
-Increases during expiration (+1 mm Hg)
Intrapleural Pressure (Pip)
Pressure in the pleural cavity that keeps lungs from collapsing
Describe the forces that tend to collapse the lungs & those that generally oppose or prevent collapse & how these forces contribute to negative intrapleural pressure (Pip)
-Lung collapsing forces pull lungs inward
-Lung enlarging forces pull lungs outward
- Pneumothorax (air in the thorax) when the pleural cavity seal is broken & air flows in separating the
visceral & parietal pleura, causing the lung to collapse
Inspiration (inhalation) Muscles Used
Diaphragm & external intercostal muscles
Expiration (exhalation) Muscles Used
Rib cage muscles, including the intercostals, the parasternals, the scalene and the neck muscles
