IB Biology: gas exchange

gas exchange

the diffusion of oxygen and carbon dioxide to and from the blood at the alveoli and the respiring tissues

ventilation

movement of air in and out of the lungs in two stages; inspiration and expiration; controlled by the movement of the diaphragm and ribcage

Terrestrial organisms exchange gases with…

the air

property of gas exhange surfaces

• permeable

• large => SA to volume ratio

• moist : allows gases to dissolve

• thin: gases must only diffuse a short surface

• concentration gradient

maintenance of concentration gradient

• continuous movement of blood in vessels

• ventilation ( breathing ) increases O2 and decreases CO2

intercostal muscles

• antagonistic muscles; internal and external intercostal muscles

• external: up and out

• internal: down and in

oxygen binding affinity

• as each oxygen binds to a haemoglobin, the shape changes, allowing oxygen to bind more easily

• this will make it so that in areas with higher oxygen concentrations, the higher the oxygen afinity there will be ( ie will bind to oxygen ).

• not a linear relationship: S curve

Bohr shift

• low ph ( Ie more CO2 present in blood ), structure of Haemoblobin change

• increasing CO2 concentration decreases affinity for O2

• deposit oxygen in areas with more CO2 ( where aerobic respiration is taking place thus where oxygen is most needed)