Please enable JavaScript.
Coggle requires JavaScript to display documents.
Physical Considerations (Countercurrent flow in fish (Oxygenated water and…
Physical Considerations
Surface area to volume ratio
In a geometric object, SA/V decreases as volume increases
Important for life; many processes decline in efficiency as SA/V decreases
Organisms aren't geometric shapes (cubes or spheres), as they have many mechanisms to do this
Fick's Law of Diffusion
Diffusion is a slow process
Controlled primarily by 3 factors
Pressure gradient (P1-P2)
Higher pressure gradient increases diffusion
Air inside of lungs is at a higher pressure than the blood
Ventilation increases P1
Perfusion decreases P2
Surface area (A)
#
Greater surface area increases diffusion
Gills, lungs, and trachea accomplish this
Path length (L)
Larger path length decreases diffusion
Circulatory system decreases the path length; gases only have to travel a short distance
Countercurrent flow in fish
Oxygenated water and deoxygenated blood run in the opposite direction
Water flow maximizes P2
Lamellae minimize L
Bird lungs
Unidirectional air flow so there are always two breaths in the respiratory system
This maximizes the pressure gradient