Blood Gas Transport

Question 1

How is oxygen moved in the blood and in what proportions?

Answer 1

Dissolving in plasma (2%)

Binding to Hb (98%)

Question 2

How is CO2 moved in the blood and in what proportions?

Answer 2

Dissolving in plasma (7%)
HCO3 (23%)
Bound to Hb (70%)

Question 3

Why do the gases dissolve in plasma?

Answer 3

To get to the Hb

Question 4

Are CO2 and O2 competitive for Hb?

Answer 4

No, bind to different binding sites

Question 5

What are the three ways of measuring O2 content?

Answer 5

Partial pressure, total O2 content, O2 saturation

Question 6

What is the unit of partial pressure?

Answer 6

KPa

Question 7

What does the partial pressure measure?

Answer 7

O2 in plasma

Question 8

What is the unit of total O2 conc?

Answer 8

Ml or L

Question 9

What happens when the oxygen-haemoglobin curve shifts to the left?

Answer 9

Decreased CO2
Increased pH
Decreased 2,3-DPG
Decreased temp

Question 10

What does it mean when the oxygen-haemoglobin curve shifts to the left?

Answer 10

Higher o2 affinity

Hb binds to more O2 at any given pO2

Question 11

What happens when the oxygen-haemoglobin curve shifts to the right?

Answer 11

Increased CO2
Decreased pH
Increased 2,3-DPG
Increased temperature

Question 12

What does it mean when the oxygen-haemoglobin curve shifts to the right?

Answer 12

Lower Hb-O2 affinity

Hb binds to less O2 at any given pO2

Question 13

What enables O2 delivery to be coupled to demand?

Answer 13

The ability of HbO2 affinity to change

Question 14

What is cyanosis?

Answer 14

Purple discolouration of skin and tissue that occurs when the deoxyhaemoglobin concentration becomes excessive

Question 15

What is central cyanosis?

Answer 15

Bluish discolouration of core, mucous membranes and extremities

Question 16

What causes central cyanosis?

Answer 16

Inadequate oxygenation of blood (hypoventilation, V/Q mismatch)

Question 17

What is peripheral cyanosis?

Answer 17

Bluish colouration confined to extremities

Question 18

Why does peripheral cyanosis happen?

Answer 18

Inadequate O2 supply to extremities (small vessel circulation issues)

Question 19

Why would hypoxia occur, even if there is adequate ventilation and perfusion?

Answer 19

If the blood doesn’t carry enough O2 to meet tissue demands

Question 20

What are the two causes of anaemia?

Answer 20

Iron deficiency (decreased production)
Haemorrhage (increased blood loss)

Question 21

How much more is COs affinity to Hb than O2?

Answer 21

> 200x

Question 22

What colour is carboxyhaemoglobin?

Answer 22

Cherry red

Question 23

What colour do people with CO poisoning go?

Answer 23

Bright red

Question 24

What are the 7 signs of CO poisoning?

Answer 24

Headaches
Nausea
Dizziness
Breathlessness
Collapse
Loss of consciousness 
Death

Question 25

Why is more (%wise) CO2 carried in the plasma than O2?

Answer 25

CO2 has a higher solubility

Question 26

What is the haldane effect?

Answer 26

Venous blood contains more CO2 than arterial blood

Question 27

Why does venous blood have more CO2 than arterial blood?

Answer 27

Deoxyhaemoglobin has a higher affinity for CO2 and H+ than oxyHb does

Question 28

What does increased oxyhaemoglobin mean for [CO2]?

Answer 28

Decreased CO2

Question 29

What are the steps in the CO2 cycle?

Answer 29

1- CO2 is produced, dissolves in plasma and enters RBCs
2- CO2+H2O->H2CO3 (catalysed by carbonic anhydrase)
3- more CO2 can now diffuse into the RBC
4- H2CO3 -> HCO3- + H+. H+ gets stuck in RBC
5- H+ accumulation is prevented by deoxyHb acting as a buffer and binding to H+
6- increased [HCO3-] creates a diffusion gradient for it to leave the cell. It’s exchanged for Cl- to maintain electrical neutrality

Question 30

What is the difference between the haldane and the Bohr effect?

Answer 30

Haldane- impact of O2 on CO2 transport

Bohr- impact of CO2 on O2 transport

Question 31

How does the Bohr effect work?

Answer 31

Binding of CO2 to Hb induces a different structural change to Hb, which reduces Hb affinity for O2

Question 32

What molecule transport is important in acid-base balance?

Answer 32

CO2

Question 33

What can be diagnosed and interpreted from analysis of arterial blood gases and pH?

Answer 33

Signs of respiratory and metabolic distress