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Key Words

Exchange Surfaces ­ a specialised area that is adapted to make it easier for
molecules to cross from one side to the other.
Gaseous Exchange ­ the movement of gases by diffusion between an organism and
its environment across a barrier e.g. the alveolus wall.

Page 2

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Inspiration (or inhalation) and Expiration (or exhalation) are the terms used to
describe breathing in and out.
Transport ­ the movement of oxygen, nutrients, hormones and water and heat
around the body.
Heart ­ a muscular pump that creates pressure to propel blood through the
arteries and around the body.…

Page 3

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Keywords

An exchange surface is a specialised area that is adapted
to make it easier for molecules to cross from one side of
the surface to the other.

Page 4

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Gaseous Exchange is the movement of gases by diffusion
between an organism and its environment across a
barrier such as the alveolus wall.

Inspiration (or inhalation) and Expiration (or exhalation)
are the terms used to describe breathing in and out.




1.2 (1) Special Surfaces for Exchange

Why organisms need special…

Page 5

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water and minerals (to maintain their water potential and to help enzyme action and other
aspects of metabolism).

Organisms may absorb these from surrounding environment, or make them inside their
cytoplasm as part of cell metabolism. All living cells also need to remove waste products
from the metabolic activities occurring…

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Gasses pass both ways through wall of alveoli. Oxygen passes from air in alveoli to blood in
capillaries, CO2 passes from blood to alveoli.
How Lungs Are Adapted For Exchange.
Large Surface Area- provides more space for molecules to pass through, individual alveoli very
small but numerous thus total surface…

Page 7

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1.2 (3) Tissues in the Lungs

The Lungs

The trachea, bronchi and bronchioles are airways that allow passage of air into the lungs
and out again. To be effective certain requirements must be met firstly, the larger
airways must be large enough to allow sufficient air to flow without obstruction…

Page 8

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1.2 (4) Measuring Lung Capacity

Breathing

When resting air moves in and out of your lungs about 12 times per min as your diaphragm
and intercostal muscles contract and relax. Each breath refreshes some of the air in your
lungs and carries away some of the CO2 generated by your…

Page 9

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Measuring Oxygen Uptake

If someone breathes in and out of spirometer for a period of time the CO2 level increases
dangerously. To avoid this, soda lime is used to absorb the CO2 exhaled, meaning the
total volume of gas in spirometer will go down because the volume of CO2 breathed…

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