The Importance of Diffusion to Living Organisms

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The Importance of Diffusion to Living Organisms

Diffusion is basically the movement of chemical species (ions or

molecules) under the influence of concentration difference. The

species will move from the high concentration area to the low

concentration area till the concentration is consistent in the whole

system. Diffusion mostly occurs in gases and liquids as these can move

freely.

The main features of an efficient diffusion system would be that it

has a large surface area, thin membrane and a continuous supply of

substances. A large surface area is needed so that high amount of

substances can be exchanged at a time while the thin membrane means

that the diffusion pathway would be short so that it is more

efficient. The continuous supply would help in maintaining a

concentration gradient which is essential for diffusion to take place.

The 2 main types of diffusion are simple and facilitated. Simple

diffusion is when a small, non-polar molecule passes through a lipid

bilayer. In this type of diffusion, a hydrophobic molecule moved into

the hydrophobic region of the membrane without getting rejected. A key

feature is that it does not need a carrier protein to take place. An

example of simple diffusion is osmosis.

Facilitated diffusion on the other hand is dependant on carrier

proteins to transport it across the membrane.

Diffusion is essential for many organisms as it is a feature of a

number of processes which control and supply vital substances to the

body in order for basic survival. A few of these are discussed below.

Gas exchange is one of these processes. It is when much needed oxygen

is obtained by the body in order for respiration to take place and the

waste CO2 is taken out of the body. In us mammals, the exchange takes

place in the lungs which contain a large number of alveoli. These are

sponge-like structures in which the diffusion takes place. They are

highly adapted to diffuse the gases as they give a large surface area

for exchange of the gases.

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