Transportation of O2 + CO2

Question 1

Describe structure of haemoglobin?

Answer 1

Hb(O2)4

Large globular conjugated protein.

4 subunits ( 2 alpha/2 beta )

Each subunit =1 haem group
~~>each bind to 1 O2 molecule

Question 2

What does ‘positive co-operativity’ mean?

Answer 2

Binding of 1st O2 changes Hb shape.

Steep concentration gradient maintained

Increases Hb’s affinity for O2

Question 3

What does ‘affinity’ mean?

Answer 3

How readily Hb binds to oxygen

Question 4

What is the oxygen dissociation curve?

Answer 4

Sigmond shape

x axis = partial pressure of oxygen

y axis = O2 saturation/Hb’s affinity for O2

Oxygen dissociation curves show the affinity of haemoglobin for oxygen.

Question 5

What does the term ‘partial pressure’ refer to?

Answer 5

Concentration of oxygen within a mixture of gases

Question 6

What happens at low pO2?

Answer 6

Low affinity

-> Little haem group bound with O2

Question 7

What happens at higher pO2?

Answer 7

Higher affinity

More Hb bind to O2

—> becomes more easier to bind to other O2. (positive co-operativity)

Question 8

What happens at very high pO2?

Answer 8

All haem group bound to O2

Hb = saturated
—> becomes oxyhaemoglobin

Question 9

What is the Bohr effect?

Answer 9

ODC shifts to right

—>Hb(O2) releases O2 more readily at high pCO2 areas.

Question 10

What does Bohr effect mean?

Answer 10

Low pCO2 area = lungs (CO2 removed from RBC into alveoli)

—> Hb = higher affinity for O2
.: binds to O2 more readily (transport O2 around body)

High pCO2 area = tissues ( body produce CO2 through respiration)

—> Hb = lower affinity for O2 .: Releases O2 more readily (more aerobic respiration)

Question 11

What happens to ODC with fetal haemoglobin?

Answer 11

ODC shifts to the left

—> Fetal Hb = higher affinity for O2.

Question 12

Why does fetal Hb need more O2?

Answer 12

For growth in mother uterus

Cannot respire.

Kinda like competing with mother.

Made from 2 alpha + 2 gamma.

Question 13

What are the different ways of transporting CO2?

Answer 13

5% = dissolved in plasma

10-20% = carbaminohaemoglobin

75-85% = CO2 converted into hydrogencarbonate ions (HCO3-) in RBC –> then transported in plasma.

Question 14

Describe process of CO2 transportation?

Answer 14

Cell = respire= CO2

Diffuse from tissue fluid -> plasma -> RBC

CO2 + H2O ⇋ H2CO3 (catalysed by carbonic anhydrase)

H2CO3 = weak acid .: dissociates

H2CO3 ⇋ H+ + HCO3-

H+ removed by buffers (Hb)

Question 15

What is the chloride shift?

Answer 15

HCO3- moves out RBC via concentration gradient

Cl- ions move into cell

Maintain electrical balance of the cell.

Travels to lungs

Process reverses