Special surfaces for exchange

AS biology Special exchange surfaces

HideShow resource information
  • Created by: lily
  • Created on: 30-10-11 16:51

Exchange surfaces appearance

  • Large surface area - more space for molecules to pass (folding walls& membranes)
  • Thin barrier- reduce diffusion distance
  • Fresh supply of molecules of 1 side - keep conc. high for osmosis
  • Removal of molecules on other side -keep conc. low for osmosis

(http://img.tfd.com/dorland/bronchiole_terminal.jpg)

e.g=

  • small intestine (nutrients absorbed)
  • liver (sugars in blood adjusted)
  • root hairs of plants (minerals & H20 absorbed)
1 of 3

Lungs as an organ of exchange

Lungs: 

  • pair of inflatable structures in chest cavity

Air: Nose -->Trachea -->bronchi & bronchioles -->alveoli (walls of which= where exchange of gases takes place)

  • protected by ribs (breathing helped by movement of ribs & diaphragm

o2 passes from air in alveoli --> blood in capillaries

co2 passes from blood --> air in alveoli

adapted for exchange:

  • Large Surface Area
  • Barrier permeable to 02 & CO2
  • Thin barrier
  • Fresh supply of CO2 from blood on one side, fresh supply of 02 from breathing on other side
2 of 3

Tissues in the lungs

3 of 3

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »