Gas Exchange in Animals
- Created by: Becky
- Created on: 14-04-13 14:22
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Gas exchange - process through which oxygen reaches cells and carbon dioxide is removed from them.
Gas exchange surfaces must have:
- a thin membrane
- large surface area
- be moist
- permeable
Fick's Law: surface area of membrane x difference in concentration across membrane all/ thickness of membrane
Large surface to volume ratio needed as more gas can diffuse due to a grater surface
Amobea
- thin
- large surface area to volume ratio
- moist
- diffuse across whole surface
- short diffusion paths
- obtains dissolved oxygen from water
Flatworms
- diffusion happens across whole body
- flattered shape = increased surface area to volume ration and shorter diffusion paths
- oxygen from water
Earthworms
- short diffusion pathway
- secrets mucus - moist
- low metabolic rate - reduces demand for oxygen
- rudimentary blood system, has blood vessels underneath surface of membrane, has blood pigments
Fish
counter current - as blood flows through gill capillaries it encounters water with a higher concentration of oxygen. Therefore the gradient is maintained and oxygen can diffuse into the blood across the whole gill surface
gills provide :
- specialised area
- large surface area
- network of blood capillaries
bony
- gills covered by flap called…
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