Components of Gas Exchange
Breathing in Air vs. Water
Oxygen Concentration
Air - 21%
Water
Varies with:
Typically less than 1%
Partial Pressures of Gases
Oxygen = 21% of atmosphere
Atmospheric pressure = 760 mm Hg (at sea level)
PO2 = .21 x 760 = 120 mm Hg
Carbon Dioxide = .03% of Atmosphere
PCO2 = .0003 x 760 = .23 mm Hg
What happens to Oxygen Concentrations as you go:
up a mountain?
deeper into a lake?
Frick’s Law of Diffusion (1855)
Which of the following would increase the rate of diffusion?
Decreasing the partial pressure gradient
Increasing the thickness of the respiratory surface
Increasing the Area of the respiratory surface
Respiratory Organs
Small animals living in water may not need respiratory organs. Why?
What type of respiratory organs do larger aquatic and marine animals have?
Fish Gills
Countercurrent Flow Maximizes O2 Diffusion
What type of Respiratory Organs do Terrestrial Organisms have?
Trachae
Tubules branch to each cell
Spiracles regulate openings
How does air move through the tracheal system?
Lungs
Most Terrestrial Vertebrates
Basic Structure
How do lungs Work?
Amphipians and Lungfish
Positive Pressure Breathing
Swallow air
Other Terrestrial Animals
Negative Pressure breathing
How does that work?
Negative Pressure Breathing in humans