adaptations for gas exchange part 2: humans insects and plants

adaptations for exchane detailed notes with diagrams, pictures and tables

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  • Created on: 15-05-11 22:16
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20. The human respiratory system includes epiglottis, trachea, bronchi, bronchioles, alveoli,
pleural membranes, ribs, intercostal muscles, diaphragm. These are involved in two
functions: ventilation an d exchange of gases.
Lungs are enclosed within the Thorax , an air tight cavity
At the base of the thorax is a sheet of muscles, the Diaphragm.
Air is drawn into the lungs via the trachea which is strengthened by rings of
in the lungs a pair of bronchi branch out into bronchioles
The exchange surface is the alveoli which are air sacs providing a large surface
They are thin and moist providing a short diffusion path and a medium for
gasses to dissolve into.
Intercostal muscle contract and relax to move the ribcage up and down.

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Mucus is a slimy
solution of mucin, which is glycoproteins with many carbohydrate chains that
make them sticky and able to trap inhaled particles. Chemical pollutants such as
sulphur dioxide, can dissolve in the mucus to form an acidic solution that irritates
the airways. The nasal passages have tiny hairs lining them as well
21.…read more

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Plants rely entirely on diffusion for the exchange of gases. Leaves are therefore thin to
shorten distances for diffusion and have a large surface area and are permeated by air
Plants photosynthesise during the day and respire at night.
the leaf is thin and flat with a large surface area
Spongy mesophyll tissue allows gases to circulate.
plant tissue contains air spaces
stomata pores on lower epidermis.
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Light can pass through to the spongy mesophyll. The spaces between mesophyll cells
allow carbon dioxide to diffuse to the cells and oxygen can diffuse away. The cells are moist
so gases can dissolve.
29. Leaves have a cuticle to prevent water loss which also reduces gaseous exchange.
30. The presence of pores, stomata, allow water and gases through.…read more

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