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Exchange of materials
Osmosis: the diffusion of water across a partially permeable
The water moves from a region of high concentration to a region of low
concentration. ( a dilute solution to a concentrated solution)
It moves down the concentration gradient.

Active Transport: the absorption of substances across a…

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These drinks are designed to help balance the concentration of fluids in and
outside of your cells. If the sports drink matches your body fluids it is called isotonic.
Some say water is just as good as sports drinks for short periods of exercise
however the sports drinks help replace…

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Ventilating the lungs:
o The lungs contain the exchange surface of the breathing system.
o They are situated in the thorax, inside the ribcage and above the diaphragm.

When we breathe in: When we breathe out:

The intercostal muscles between the ribs The intercostal muscles and the
and the diaphragm…

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Artificial breathing aids:
There are many reasons why someone cannot get enough oxygen into their

o The alveoli may be damaged: the surface area for gas exchange is reduced.
o The tubes leading to the lungs may be narrowed: less air can move easily through
o The person…

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o Positive pressure aids are smaller and can be linked to computers for better control
at home or the hospital.

Exchange in the gut:

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o Food we eat gets digested in the gut into small,
soluble amounts that can be easily absorbed into the blood
in the small intestine.
o The villi line the inner surface of the small intestine
and are the exchange surface for food molecules.
o They are long finger-like projections…

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Transpiration: the passage of gases through fine tubes because
of differences in pressure or temperature.

o Plants take up water through the roots and the water passes through the
plant to the leaves. In the leaves the water evaporates from the leave cells
and the water vapour diffuses out through…


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