Haemoglobin and gas transport

Question 1

How much O2 is dissolved in plasma ?

Answer 1

3 mL

Question 2

What is the O2 carrying capacity of blood?

Answer 2

200 mL

Question 3

What is haemoglobin carrying capacity ?

Answer 3

197 mL

Question 4

What determines partial pressure of O2 in plasma?

Answer 4

It is determined by O2 solubility in plasma and partial pressure of O2 gas that drives diffusion

Question 5

What is O2 solubility in plasma?

Answer 5

0.03 ml/L/mm Hg

Question 6

How much plasma do we have per L of blood?

Answer 6

3 ml/L

Question 7

How much blood do we have ?

Answer 7

We have from 4.7 to 5L of blood.

Question 8

What is the O2 demand in tissues?

Answer 8

250 ml/min

Question 9

How much O2 is delivered to tissues per minute?

Answer 9

200 x 5 = 1000 ml/min

Question 10

Describe haemoglobin

Answer 10

It consists of 4 polypeptide chains, 2 alpha and 2 beta chains, each has one harm group, so one haemoglobin can carry 4 molecules of O2.

Question 11

What type of biding is present in haemoglobin with O2?

Answer 11

cooperative binding

Question 12

What is normal haemoglobin O2 saturation?

Answer 12

97-98%

Question 13

What is the major determinant of haemoglobin O2 saturation ?

Answer 13

Partial pressure of O2

Question 14

How long is the contact time and how long is the oxygenation process?

Answer 14

contact time is 0.75 s and saturation takes 0.25s

Question 15

Name all the different types of haemoglobin

Answer 15

HbA in RBC, HbA, glycolysated HbA1a, HbA1b, HbA1c, HbA2 variant of HbA, and foetal HbF (still present in adults)

Question 16

What portion of haemoglobin is HbA?

Answer 16

92%

Question 17

What chains are in HbA?

Answer 17

2 alpha and 2 beta

Question 18

What chains are in haemoglobin HbA2?

Answer 18

2 alpha and 2 delta

Question 19

What chains are in HbF?

Answer 19

2 alpha and 2 gamma

Question 20

At what partial pressure there is big change in O2 saturation ?

Answer 20

at 60 mmHg, saturation of 90%

Question 21

What is the O2 saturation at pressure 40 mmHg?

Answer 21

The saturation is 75%, it is reserve, can be used when there is high metabolic demand

Question 22

Rank haemoglobin, myoglobin and foetal haemoglobin in terms of affinity for O2

Answer 22

myoglobin has the highest affinity, foetal haemoglobin and normal haemoglobin

Question 23

Where is the most of myoglobin present?

Answer 23

in oxidative fibres in muscle

Question 24

What partial pressure is called the dead zone and why

Answer 24

40 mmHg is dead zone and there is very little gradient for diffusions to tissues

Question 25

What is the effect of anaemia on O2 carrying capacity, saturation and partial pressure of O2?

Answer 25

The total carrying capacity is reduced, but the partial pressure and saturation remains the same

Question 26

What can cause anaemia ?

Answer 26

iron deficiency, B12 deficiency or haemorrhage

Question 27

How can haemoglobin affinity for O2 be reduced( more O2 is given off)?

Answer 27

By low pH, increased PCO2, and increased temperature and added DPG

Question 28

What is DPG?

Answer 28

DPG is diphosphoglycerate, it is produced by RBC as a response to hypoxia. In people living in high altitudes, cardiac and lung problems

Question 29

What is the name of the effect that shift the curve to the right as a response to lower pH etc?

Answer 29

Bohr effect

Question 30

What is the affinity of haemoglobin to CO?

Answer 30

It is 250 x higher than the affinity for O2

Question 31

What is formed when CO binds to haemoglobin ?

Answer 31

carboxyhaemoglobin

Question 32

At what partial pressure carboxyhemoglobin starts to form?

Answer 32

at 0.4 mmHg

Question 33

What are the signs of CO poisoning ?

Answer 33

headache, deep red colour of cheeks, skin and mucous membranes, nausea, confusion, hypoxia

Question 34

Name the 5 types of hypoxia.

Answer 34

Hypoxic hypoxia, anaemic hypoxia, ischaemic, histotoxic and metabolic

Question 35

What causes hypoxic hypoxia ?

Answer 35

Due to reduction in O2 diffusion in lungs either due to low O2 in atmosphere or lung pathology

Question 36

What causes anaemic hypoxia ?

Answer 36

Low level of red blood cells

Question 37

What causes ischaemic hypoxia?

Answer 37

Herat disease and sufficient pumping of blood around the body

Question 38

What causes histotoxic hypoxia?

Answer 38

Poising such as CO

Question 39

What causes metabolic hypoxia?

Answer 39

Increased demand of O2 by tissues which is not met by the supply

Question 40

How is CO2 transported around the body?

Answer 40

Dissolved in plasma 7%, as bicarbonate ion formed in RBC 70%, as carbamino haemoglobin 23%

Question 41

How are bicarbonate ions formed?

Answer 41

CO2 into red blood cells, combine with water forming H2CO3 with the help gof enzyme carbonic anhydrase, dissociate to HCO3- , out to plasma by chloride shift, H+ ions are buffered by deoxyhaemoglobin