Lecture 19 - Blood gas transport

Question 1

What does gas transport carry around the body?

Answer 1

O2 from alveoli to systemic tissues
CO2 from systemic tissues to alveoli

Question 2

Through which process does gas exchange occur?

Answer 2

Diffusion

Question 3

What factors determine efficiency/ability of gas exchange?

Answer 3

Diffusion surface area
Diffusion distance for gases
Concentration gradient between alveolar air and blood
Solubility of gases
Coordinated blood flow and air flow

Question 4

What is Dalton’s law of partial pressure?

Answer 4

The total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture

Question 5

What is the definition of partial pressure?

Answer 5

The pressure exerted by each gas
It is directly proportional to its percentage in the total gas mixture

Question 6

What is Henry’s law in relation to solubility?

Answer 6

The amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in air
At equilibrium, the amount of dissolved gas in a solution is proportional to the partial pressure of that gas

Question 7

According to Henry’s law, what happens as the partial pressure of gas increases?

Answer 7

The number of gas molecules increases

Question 8

What is the structure of haemoglobin?

Answer 8

4 globular protein subunits, 2 alpha 2 beta
Each subunit contains globin and haem

Question 9

What occurs as haemoglobin becomes oxygenised?

Answer 9

It is a rapid and reversible reaction
Each haemoglobin molecule will bind to 4 molecules of oxygen

Question 10

What percentage of oxygen is transported in blood with haemoglobin?

Answer 10

97%

Question 11

What is the meaning of haemoglobin saturation?

Answer 11

The percentage of haem units in a haemoglobin molecule that contain bound oxygen

Question 12

What factors affect the binding of oxygen to haemoglobin?

Answer 12

PO2 of blood
Blood pH
Temperature
State of the oxygen thats attempting to bind

Question 13

What occurs as oxygen unloads into tissues?

Answer 13

pH decreases
CO2 increases
The oxygen dissociation curve shifts to the right
Temperature increases
2,3-diphosphoglycerate increases

Question 14

What is carboxyhaemoglobin?

Answer 14

CO2 binds tighter than O2
Reduces ability of oxygen to bind to haemoglobin

Question 15

What is methaemoglobin

Answer 15

Fe2+ oxidised by Fe3+
Unable to carry O2
Slowly converted back

Question 16

What is foetal haemoglobin?

Answer 16

Has a higher affinity for oxygen
Role in transferring oxygen across placenta

Question 17

How is carbon dioxide generated?

Answer 17

By aerobic metabolism in peripheral tissues

Question 18

How is 70% of carbon dioxide transported?

Answer 18

Converted to carbonic acid formation, H2CO3- and transported in plasma as bicarbonate ion HCO3

Question 19

How is 23% of carbon dioxide transported?

Answer 19

Bound to haemoglobin as carbaminohaemoglobin

Question 20

How is 7% of carbon dioxide transported?

Answer 20

Dissolved in plasma

Question 21

What is the process of the Haldane effect in the lungs?

Answer 21

Oxygenation of haemoglobin occurs
Haemoglobin undergoes a conformational change
It has lower affinity for H+ ions
Buffering power decreases
H+ are released

Question 22

What is the process of the Haldane effect in the tissues?

Answer 22

Deoxygenation of haemoglobin
Hb undergoes conformational change
It has a higher affinity for H+ ions
Buffering power increases
H+ uptake