Gas Exchange and Circulatory Systems

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Gas Exchange and circulatory systems
Most gas exchange surfaces have two common areas:
They have a large surface area
They're thin (one cell thick) Thus a
short diffusion pathway
The organism also maintains a steep
concentration gradient of gases across
the exchange surface
These factors.. Increase the rate of diffusion
Single celled organisms
They absorb and release gases by diffusion
through their outer surface.
They have a relatively large surface area, thin
surface and short diffusion pathway so, there's
no need for a gas exchange system!
Circulatory system - Locusts

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Have tiny air filled pipes call tracheae to exchange gas.
Air moves into the tracheae via pores on the surface called
O2 then travels down the concentration gradient to the cells.
CO2 from the cells moves down its own gradient to the spiracles
to be released into the atmosphere.
The tracheae branch off to smaller tracheoles with thin,
permeable walls that go to individual cells. So...…read more

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Circulatory system - Fish
Due to a lower concentration
of oxygen in water than air,
fish needed to adapt;
1) Water enters through the mouth and out through the gills
2) Each gill's made of numerous thin gill filaments to give a big surface area for gas
3) The filaments are covered in tiny structures called lamellae that increase surface
area more
4) Lamellae have lots of capillaries and a thin surface layer of cells to speed up
diffusion..…read more

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Dicotyledonous plants
Exchange gases at the surface of mesophyll cells. Plants need CO2 for
photosynthesis and give O2 as waste. They use O2 for respiration giving CO2
as waste.
The main area for exchanging these is the surface of the mesophyll cells in
the leaf. They're well adapted for their job as they have a large surface
These are inside the leaf; gases move in and out through pores in the
epidermis called stomata (single is stoma).…read more

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Control of water
Plants and insects have adaptations to minimise water loss during gas exchange.
If insects lose too much water, they close their spiracles using muscles. The plants
have a waterproof, waxy cuticle on the body with tiny hairs by the spiracles to
reduce evaporation.
Plants' stomata usually stay open in the day to have effective gas exchange. Water
enters the guard cells making them turgid, opening the stomatal pore. If the plant's
dehydrated, the guard cells become flaccid which closes the pore.…read more

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The lungs
The body needs a constant supply of oxygen for the process of respiration.
The gas carbon dioxide is produced as a waste product.
The lungs are found in the part of the body called the thorax and this is
separated from our digestive organs by the diaphragm. The main job of
the breathing system is to carry gases in and out of the lungs.…read more

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