Gas Exchange

Breathing rate
Number of breaths in a minute. Breathing rate (breaths per minute) = (Number of breaths/ time taken(s)) x 60
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Countercurrent flow
Water flows in the opposite direction to the blood. This arrangement ensures that a concentration gradient is maintained along the length of the gills and so gas exchange is more efficient and the rate of diffusion is kept high
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Elastic fibres
Fibres found in the trachea, bronchi, bronchioles and alveoli. They stretch when the lungs inflate and then recoil, helping to force air out of the lungs
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Expiration
Breathing out. External intercostal muscles relax and move the rib cage down and in. Diaphragm muscles relax and the diaphragm becomes more dome shaped, curving upwards.
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Fick's law
Rate of diffusion is proportional to the surface area and the concentration gradient and is inversely proportional to the thickness of the exchange surface
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Inspiration
Breathing in. External intercostal muscles contract and move the rib cage up and out. Diaphragm muscles contract and the diaphragm flattens and moves downwards
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Residual volume
Volume of air left in the lungs after forced expiration
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Smooth muscle
Type of muscle found in the walls of the trachea, bronchi and larger bronchioles. They control the diameter of these airways, increasing or decreasing resistance to air flow
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Spirometer
Apparatus used to measure breathing rate, tidal volume, vital capacity and oxygen consumption. Uses soda lime to absorb carbon dioxide
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Surface area to volume ratio
Surface area divided by volume : 1. As size increases, SA:Vol ratio decreases
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Tidal volume
Volume of air exchanged in one breath
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Vital capacity
Maximum volume of air that can be exchanged in one breath after forced expiration
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Other cards in this set

Card 2

Front

Water flows in the opposite direction to the blood. This arrangement ensures that a concentration gradient is maintained along the length of the gills and so gas exchange is more efficient and the rate of diffusion is kept high

Back

Countercurrent flow

Card 3

Front

Fibres found in the trachea, bronchi, bronchioles and alveoli. They stretch when the lungs inflate and then recoil, helping to force air out of the lungs

Back

Preview of the back of card 3

Card 4

Front

Breathing out. External intercostal muscles relax and move the rib cage down and in. Diaphragm muscles relax and the diaphragm becomes more dome shaped, curving upwards.

Back

Preview of the back of card 4

Card 5

Front

Rate of diffusion is proportional to the surface area and the concentration gradient and is inversely proportional to the thickness of the exchange surface

Back

Preview of the back of card 5
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