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SA:V ratio and Gas Exchange - Coggle Diagram

- - - - short diffusion pathway as walls of tracheoles are thin and permeable
      - large SA/V due to branching tracheal network of tracheoles and tracheae that branch into tissues to reach individual cells
      - diffusion gradient maintained by abdominal pumping, concentration of CO2 high at the end of tracheoles and O2 conc at the end of tracheoles high
  - - - interconnecting air spaces in spongy mesophyll so gases diffusing into leaf are readily in contact with mesophyll cells- maintains diffusion gradient
      - large sa/v ratio because large sa/v with lots of stomata and air spaces increase surface area of mesophyll cells
      - short diffusion pathway for gases as leaf has large sa/v and lots of stomata on underside of so no cell is far from stomata and atmospheric air. + bc diffusion happens in the gas phase so overall short fast pathway
  - - - large SA/V by gill filaments and gill lamellae
      - short diffusion pathway by capillary beds and thin surface layer of cells in gill lamellae
      - diffusion gradient maintained by ventilation and mass transport in blood , water flow over the lamellae and blood flow thru capillaries in lamellae in opposite directions