Gas Exchange in animals (1 Viewer)

carmot

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They all have increased surface area for gas exchange - fish have gill filaments covered with lamellae, frogs are small to maintain a high SA:V ratio and use their skin and basic lungs, while lungs in mammals have extensive branching.

They also need to be kept moist. No problem in fish, while frogs always live in moist environments and need to stay wet. Mammals have internal gas exchange surfaces and mucus to maintain moisture.

There are also many capillaries that service the gas exchange surfaces, with very little diffusion needed, only two cells (gas exchange surface and capillary wall).

Not sure if you could also add that at these surfaces, oxygen diffuses into the blood while carbon dioxide diffuses out...
 

Squishxmishyx

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Fish
In fish, the repiratory surfaces are usually gills over which water flows. Gills are usually finely divided, and the incoming water flows over a large surface area at the one time. There is a plentiful lood supply to transport the gases to a from the fills. The blood flows in the opposite direction to the flow of water. This counter-current blood flow increases the efficiency of the gas exchange process.

Frogs
Have two respiratory surfaces; the lungs and the skin. Oxygen from the air diffuses into the moist skin and is transported by blood to the heart. Air is passed in and out by the pumping movement of the floor of the mouth(buccal pump) and the opening and closing of the nostrils.

Mammals
Gases are exchanged in the lungs. The surface area of contact between the blood and air is increased by the convolution of the lungs into lobes, by the branching of the bronchioles into smalller tubules. The division of the tubules into cluster of tin air sacs are called alveoli. Gas exchange occurs across the thin walls of the alveoli. Air is moved in and out of the lungs in the proces of breathing brought about by muscles of the chest wall and diaphragm.


LOL that was great revision.
 

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