Gas exchange

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Why is difusion alone enough for single celled organisms?
The metabolic activity is low and the SA:Vol is large.
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Name 4 features of a specialised exchange surface?
High SA, thin layers, good blood supply, diffusion gradient
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Why does a high SA help with gas exchange?
Provides a suface for gas exchange
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How does the naval cavity help with gas exchange?
Large SA with good blood supply to warm air to body temperature, hairy lining which secretes mucus to protect from infection, moist surfaces whih reduce evaporation.
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How is the trachea adapted for gas exchange?
Supported by cartilage to keep it open, lined with cilliated epithilium and goblet cells to secrete mucus and stop infection,.
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How are bronchioles suitable for gas exchange?
Have smooth muscle to constrict them ad let them dilate, controls amount of air going into lungs.
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What is the diameter of an alveolit?
200-300um
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How does elastic recoil help alveoli?
Allows them to stretch and fill with air.
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What are the main adaptations of alveoli for gas exchange?
Large SA, thin walls (1 cell thick) short diffusion path, good blood supply (near capillaries), good ventilation (steep concentration gradient.
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What does surfactant do?
Allow alveoli to remain inflated and reduce water loss.
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Describe inspiration?
Diaphragm contract and flatten down, external intercoastal muscles contract, ribs pulledu up, volume of thorax increases, pressure is now below atmospheric, air comes in,
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Describe expiration?
diaphragm relaxes and curves upwards, intercoastal muscles relax, ribs relax, volume of thorax decreases, pressure above atmospheric, air moves out,
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Why do smokers get more infections?
goblet cells secrete musucs, cillia brush it up to throat to swlloe, kills in stomach acid, in smokers cillia is damaged, mucucs in throat, traps dust, keep infection etc in thorat
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Name two pieces of equipment that measure the capacity of the lungs?
Spirometer and Peak flow meter
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How does air enter an insect?
Through spiracles
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What do sphincters do?
Keep the spiracles closed so that water loss is minimsed
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Describe the trachea in insects?
Leads on from spiracles, chittin keeps it open, impermeable so not much gas exchange takes place in trachea, branch into tracheoles
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Describe the tracheoles in insects?
0.6-0.8um diameter, permeable, large SA, lactic acid build up causes water to move out of tracheoles by osmosis.
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How does the trachea adapt to help insects with high energy demands?
air is pumped by the thorax, changes volume of bod and pressure of thorax. Trachea can act as air resovior, increase the amount of air moved through system.
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How do gills help fish with gas exchange?
Increase SA, water flows over gills, good blood supply, thin layers,
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How do fish exchange gas in water?
gill filmaments overlap, increases resistance, sows down water, more time for gas exchange... steep concentration gradient is needed, counter current system, remove 80% oxygen from water.
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Card 2

Front

Name 4 features of a specialised exchange surface?

Back

High SA, thin layers, good blood supply, diffusion gradient

Card 3

Front

Why does a high SA help with gas exchange?

Back

Preview of the front of card 3

Card 4

Front

How does the naval cavity help with gas exchange?

Back

Preview of the front of card 4

Card 5

Front

How is the trachea adapted for gas exchange?

Back

Preview of the front of card 5
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