Physiology of Oxygen & CO2

Question 1

State Henrys Law

Answer 1

The amount of a gas dissolved in a given type and volume of liquid at a constant temperature is: proportional to the partial pressure of the gas in equilibrium with the liquid

if the partial pressure in the gas phase is increased the concentration of the gas in the liquid phase would increase proportionally

Question 2

What two ways is blood present in the blood?

Answer 2

bound to haemoglobin - 98.5%
physically dissolved (very little O2) - 1.5%

Question 3

Describe haemoglobins relationship with oxygen?

Answer 3

Haemoglobin can form a reversible combination with O2
Each Hb molecule contains 4 haem groups
Each haem group reversibly binds to one O2 molecule
Haemoglobin is considered fully saturated when all the Hb present is carrying its maximum O2 load
The PO2 is the primary factor which determine the percent saturation of haemoglobin with O2

Question 4

What is the oxygen content of arterial blood determined by?

Answer 4

haemoglobin

Question 5

Name the 2 special features of haemoglobin in relation to oxygen?

Answer 5

co-operativity - binding of one O2 to Hb increases the affinity of Hb for O2
Sigmoid - Flat upper portions of graph means that moderate fall in alveolar PO2 will not affect oxygen loading. Steep lower part means that the peripheral tissues get a lot of oxygen for a small drop in capillary PO2

Question 6

What is the Bohr Effect?

Answer 6

a shift of the oxygen/haemoglobin curve to the right.

Due to increased release of O2 by conditions at the tissues

Question 7

What is different about foetal haemoglobin (HbF) compared to adult?

Answer 7

HbF has 2 alpha and 2 gamma subunits

HbF has a higher affinity for O2

Question 8

What does presence of myoglobin in the blood indicate?

Answer 8

muscle damage

Question 9

Describe the characteristics of myoglobin?

Answer 9

One haem group per myoglobin molecule. 
No cooperative binding of O2. 
The dissociation curve is hyperbolic.
Myoglobin releases O2 at very low PO2. 
Provides a short-term storage of O2 for anaerobic conditions

Question 10

How is CO2 transported in the blood?

Answer 10

Solution (10%)
As Bicarbonate (60%)
As Carbamino compounds (30%) (sometimes called carbamino-haemoglobin)

Question 11

How is bicarbonate formed in the blood?

Answer 11

chloride shift
CO2 + H2O <> H2CO3 <> H+ + HCO3
enzyme = Carbonic Anhydrase (found in red blood cells)

Question 12

What is the Haldane effect?

Answer 12

removing O2 from Hb increases the ability of Hb to pick-up CO2 and CO2 generated H+

Question 13

What do the Bohr effect and Haldane effect work togehter to cause?

Answer 13

O2 liberation and uptake of CO2 & CO2 generated H+ at tissues