Week 7 - Gas Exchange

Question 1

What is the partial pressure of a gas?

Answer 1

The pressure contributed by a single gas in a mixture of gases.

Question 2

What in Henrys’ law?

Answer 2

The amount of gas in a solution depends on the partial pressure of gas and it’s solubility (CO2 in air has low PP but high solubility, O2 has lower solubility but higher PP)

Question 3

Describe Ficks’ Law

Answer 3

Movement of gas molecules from an area where gas exerts high PP to an area where gas exerts low PP

Question 4

What factors influence diffusion rate?

Answer 4

Area of barrier
Diffusing ability of gas
Thickness of barrier
PP difference
Temperature

Question 5

Describe the structure of haemoglobin

Answer 5

2 alpha polypeptide chains
2 beta polypeptide chains
Each chain forms a protein subunit with a single heme molecule

Question 6

Describe the oxyhaemoglobin dissociation curve

Answer 6

4 subunits on Hb molecule react with Oxygen in sequence
Difficult for Hb to start getting on or letting go
Once one gets on, it’s easy for 2 and 3 but harder for the last 1
Same in reverse makes an S shaped curve

Question 7

What factors affect dissociation from Hb?

Answer 7

Temp
PP of CO2
pH
2.3-DPG - produced in response to lower O2 levels and makes Hb give up O2
Anaemia, CO, NO

Question 8

How is CO2 transported?

Answer 8

5-10% in solution in plasma
5-10% bound to amino acids
80-90% as bicarbonate ions

Question 9

What in the Henderson Hasselback Equation?

Answer 9

H20 + CO2 – HCO3 – H + CO3

Carbonic Anhydrase

Question 10

Describe the Bohr effect

Answer 10

Effect of pH on O2 dissociation curve
Deoxyhaemoglobin more readily accepts H+
Shifts curve to right
OxyHb is facilitated to release it’s Hb

Question 11

What is the haldane effect?

Answer 11

Oxyhaemoglobin presense facilitates the movement of CO2 out of the blood, e.g. at the lungs
The presence of deoxyHb facilitates more CO2 to be carried into the blood, e.g. at the tissues