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Physiology 3001 > Gas transport > Flashcards

Gas transport Flashcards

1
Q

What are the two main ways oxygen is carried in the blood?

A
  • Dissolved in plasma

- Attached to haemoglobin

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2
Q

What is the amount of drug dissolved in plasma directly proportional to?

A

Partial pressure

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3
Q

What is haemoglobin made of?

A
  • Haem - iron containing compound

- Globin - protein of 4 polypeptide chains

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4
Q

What causes the sigmoidal oxygen-haemoglobin dissociation curve?

A
  • Positive co-operative binding - once first O2 is bound, the next three are easier to bind
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5
Q

What is the Oxygen saturation of haemoglobin at the tissues roughly?

A

75%

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6
Q

What percentage of bound oxygen is normally unloaded at the tissues?

A

25% - leaving a large reserve without needing to increase RR or CO

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7
Q

What does the flat upper plateau on the oxygen saturation curve result in?

A

Means that even if PO2 falls, saturation is not greatly altered, so at altitude O2 supply is still usually adequate

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8
Q

What is the PO2 of oxygen at the level of the tissues?

A

40mmHg

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9
Q

What factors shift the oxygen saturation curve to the right?

A
  • Increased temperature
  • H+
  • CO2
  • 2,3 - biphosphoglycerate
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10
Q

What does a shift to the right mean for haemoglobin?

A
  • Modifies the 3-D structure of haemoglobin, decreasing its affinity for oxygen
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11
Q

What is the Bohr effect?

A
  • Increased CO2 leads to an increase in H+ which weakens the HB-O2 interaction
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12
Q

Where does the curve shift to at the lungs?

A

Shifts to the left

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13
Q

What is the purpose of ‘warming up’ muscles before exercise?

A

Results in a shift to the right in the curve meaning the haemoglobin is better at releasing O2

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14
Q

What does an increase in CO2 result in?

A

A shift to the right meaning O2 is released more easily

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15
Q

How do you calculate total O2?

A

(Hb x capacity x %saturation) + amount dissolved

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16
Q

What is normal Hb concentration in the blood?

A

150g/L

17
Q

What is the usually capacity of haemoglobin?

A

1.35ml/g Hb (usually lies between 1.35 and 1.39)

18
Q

What is the usual arterial blood saturation?

A

98%

19
Q

Why is arterial blood saturation only 98%

A

Bronchial arteries supply 2% of blood to lungs

20
Q

What are the different methods of transport of CO2 in the blood?

A
  • Dissolved in plasma
  • Bound to haemoglobin
  • As bicarbonate
21
Q

What percentage of CO2 is disolved in plasma?

A

7 - 10%

22
Q

What percentage of CO2 is bound to haemoglobin?

A

10 - 20% bind to the amino acids not the haem

23
Q

What is loading and unloading of CO2 from haemoglobin directly related to?

A
  • PCO2

- Degree of oxygenation of Hb

24
Q

What is the haldane effect?

A

Deoxygenation of Hb increases its ability to bind CO2, (eg in the tissues) and vice versa in the lungs, oxygenation of Hb releases CO2 into plasma for transport into alveoli

25
Q

What percentage of CO2 which is transported is in the form of bicarbonate?

A

70 - 80%

26
Q

What is the unstable compound which CO2 produces when dissolved in water?

A

Carbonic acid

27
Q

What enzyme present in RBC makes the CO2 conversion to carbonic acid very rapid?

A

CArbonic anhydrase

28
Q

Write the chemical equation for CO2 when it enters the blood?

A

CO2 + H2O H2CO3 H+ + HCO3-

29
Q

What is the chemical formula for carbonic acid?

A

H2CO3

30
Q

What is the chemical formul for bicarbonate?

A

HCO3-

31
Q

What chemical causes an electrical balance in the plasma?

A

Cl-

32
Q

Where is the majority of bicarbonate produced?

A

Inside the RBC

33
Q

What is the Henderson-Hasselbach equation?

A

pH = pK + (log[bicarbonate])/(CO2)

34
Q

What is the pK value?

A

6.1

35
Q

What is acidosis?

A

pH < 7.35

36
Q

What is alkalosis?

A

pH > 7.45

Physiology 3001 (20 decks)

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