exchange surfaces

• The lungs help transfer O2 to the blood and remove CO2 from our blood.
• The lungs contain millions of alveoli.
• Alveoli are specialised to maximise diffusion.
• Name ways alveoli are specialised to maximise diffusion.

  Enormous surface area

  moist lining for gas dissolving

  very thin walls (one cell thick)

  good blood supply
• Small intestine have millions of little projections called what?

  villi
• Villi increase surface area so digested food is absorbed..

  quicker
• Name how villi are adapted to their function

  single layer of surface cells

  very good blood supply
• the underside of a leaf is an exchange surface
• Underside of a leaf is covered in stomata which CO2 diffuses through, and water + O2 diffuse out of
• CO2 diffuses into the space in leaves then into the cells where photosynthesis happens
• Guard cells control stomata size
• Gills are how gas exchange in fish takes place
• In fish, water enters through the mouth and passes out through the gills.
• Each gill in a fish is made from thin plates called gill filaments which gives them a large surface area.
• Gill filaments are covered by lamellae which increase surface area.
• Give how lamellae are adapted for function.

  lots of blood capillaries

  thin surface area

  blood flows one direction and water flows in the opposite which maintains large concentration gradient

  high O2 concentration in water than blood so as much O2 as possible diffuses from water to blood
• Gas exchange happens in the lungs
• Adaptations of alveoli:

  large surface area

  moist lining for gas dissolving

  thin walls

  good blood supply
• Adaptations of villi:


  single layer of surface cells

  very good blood supply

  large surface area
• Villi allows digested food to be absorbed into the bloodstream a lot quicker.
• Villi are millions of small projections in the small intestine that increase the surface area for absorption
• The structure of leaves lets gases diffuse in and out.
• The flattened shape of the leaf increases the area of the exchange surface so it is more effective.
• Oxygen and water vapour diffuse out through the stomata.
• Stomata size is controlled by guard cells.