Gas Exchange Flashcards
Why is gas exchange less efficient in air than in water?
Air has low viscosity and density, and high Po2
Why is gas exchange more efficient in water?
Water is dense, viscous, and has low dissolved O2
How does blood flow in fish gills?
In the opposite direction to water
Why is blood always less saturated with O2 than the water in fish gills?
Because blood flows opposite to water, maintaining a gradient
How much O2 is removed from water by fish gills?
More than 80%
Gas exchange
takes place in___?
alveoli
What muscles are involved in increasing and decreasing chest volume?
Diaphragm & rib-cage muscles
How is pressure altered during breathing in mammals?
By changing the volume of the chest
What ion accumulates in guard cells when stimulated by light?
K+ (potassium)
What happens when K+ enters guard cells?
Water enters, cells bow, and stomata open
What structural features help stomata open?
End attachment, thick wall, cellulose microfibril orientation
