Transport in animals

Bohr effect

Oxygen dissociation curve will form a sigmoid shape shifting to the right

Haemoglobin affinity for oxygen high co2

Oxyhaemoglobin has a lower affinity for oxygen in area of High CO2

Haemoglobin affinity for oxygen low co2

Oxyhaemoglobin has a higher affinity for oxygen in area of Low CO2

Respiring tissues

• When haemoglobin has a low affinity for oxygen

• It can release oxygen more readily

• This is released in respiring cells - more CO2

• Need oxygen for respiration

Lungs

• Higher affinity for the oxygen

• Will want to bind to the oxygen more readily

• Binds to oxygen to be transported around the body

How does fetal Hb differ

• Fetal Hb has a higher affinity curve shifts to the left

• Fetal Hb has a higher affinity for O2

• Fetal Hb can get oxygen from mothers blood in placenta

• Fetus cannot respire for themselves needs O2 for growth

Hb structure

• Haemoglobin as a quaternary structure

• Made of 2 alpha and 2 beta subunits

• Haem group in the center were oxygen binds

• Each haemoglobin molecule can bind to 4 oxygen molecules

How does it become easier for O2 to bind to haemoglobin

• Once one oxygen molecule has binded to the haem group

• There is a conformational change making it easier for more O2 to bind

• Increasing haemoglobin affinity for O2

O2 dissociation curve

As partial pressure of O2 increases so does the saturation of haemoglobin

Why is O2 affinity low in high CO2 conc

• CO2 is acidic changing the structure of haemoglobin

• Lowering its affinity for O2

• A small decrease in pH will result in a large decrease in percentage saturation of O2

Ways Co2 can be transported

• 5% Dissolves directly into blood plasma

• 20% Forms carbaminohemoglobin with amino group

• 75% Hydrogencarbonate ions

CO2 + H20 —→ Carbonic acid

Sped up by catalyst by carbonic anhydrase in -rbc

Low CO2 in rbc

Forms a steep concentration gradient - high rate of CO2 diffusing into rbc’s

Carbonic acid splits into H+ and HCO3-

HCO3- diffuses to blood plasma

Charge imbalance - Cl - diffuses in (chloride shift)

Haemoglobin binds to H+ —→ Haemoglononic acid