Haemoglobin and gas transport Flashcards

1
Q

How much O2 is dissolved in plasma ?

A

3 mL

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2
Q

What is the O2 carrying capacity of blood?

A

200 mL

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3
Q

What is haemoglobin carrying capacity ?

A

197 mL

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4
Q

What determines partial pressure of O2 in plasma?

A

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

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5
Q

What is O2 solubility in plasma?

A

0.03 ml/L/mm Hg

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6
Q

How much plasma do we have per L of blood?

A

3 ml/L

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7
Q

How much blood do we have ?

A

We have from 4.7 to 5L of blood.

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8
Q

What is the O2 demand in tissues?

A

250 ml/min

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9
Q

How much O2 is delivered to tissues per minute?

A

200 x 5 = 1000 ml/min

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10
Q

Describe haemoglobin

A

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.

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11
Q

What type of biding is present in haemoglobin with O2?

A

cooperative binding

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12
Q

What is normal haemoglobin O2 saturation?

A

97-98%

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13
Q

What is the major determinant of haemoglobin O2 saturation ?

A

Partial pressure of O2

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14
Q

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

A

contact time is 0.75 s and saturation takes 0.25s

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15
Q

Name all the different types of haemoglobin

A

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

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16
Q

What portion of haemoglobin is HbA?

A

92%

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17
Q

What chains are in HbA?

A

2 alpha and 2 beta

18
Q

What chains are in haemoglobin HbA2?

A

2 alpha and 2 delta

19
Q

What chains are in HbF?

A

2 alpha and 2 gamma

20
Q

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

A

at 60 mmHg, saturation of 90%

21
Q

What is the O2 saturation at pressure 40 mmHg?

A

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

22
Q

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

A

myoglobin has the highest affinity, foetal haemoglobin and normal haemoglobin

23
Q

Where is the most of myoglobin present?

A

in oxidative fibres in muscle

24
Q

What partial pressure is called the dead zone and why

A

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

25
Q

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

A

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

26
Q

What can cause anaemia ?

A

iron deficiency, B12 deficiency or haemorrhage

27
Q

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

A

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

28
Q

What is DPG?

A

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

29
Q

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

A

Bohr effect

30
Q

What is the affinity of haemoglobin to CO?

A

It is 250 x higher than the affinity for O2

31
Q

What is formed when CO binds to haemoglobin ?

A

carboxyhaemoglobin

32
Q

At what partial pressure carboxyhemoglobin starts to form?

A

at 0.4 mmHg

33
Q

What are the signs of CO poisoning ?

A

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

34
Q

Name the 5 types of hypoxia.

A

Hypoxic hypoxia, anaemic hypoxia, ischaemic, histotoxic and metabolic

35
Q

What causes hypoxic hypoxia ?

A

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

36
Q

What causes anaemic hypoxia ?

A

Low level of red blood cells

37
Q

What causes ischaemic hypoxia?

A

Herat disease and sufficient pumping of blood around the body

38
Q

What causes histotoxic hypoxia?

A

Poising such as CO

39
Q

What causes metabolic hypoxia?

A

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

40
Q

How is CO2 transported around the body?

A

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

41
Q

How are bicarbonate ions formed?

A

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