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Human Systems and Anatomy > Gas Transport > Flashcards

Gas Transport Flashcards

1
Q

what is gas diffusion

A

movement of gas throughout the respiratory system occurs via diffusion

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2
Q

what are some anatomical and physiological properties that facilitate gas diffusion

A
  • large surface area for gas exchange
  • large partial pressure gradients
  • gases with advantageous diffusion properties
  • specialised mechanisms for transporting oxygen and carbon dioxide between lungs and tissues
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3
Q

what is total pressure

A

the sum of the partial pressures or tensions of a gas

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4
Q

what is the barometric pressure at sea level

A

760 mmHg

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5
Q

what is Pgas

A

partial pressure of a gas

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6
Q

what is Fgas

A

fraction of a gas

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7
Q

what does partial pressure equal

A

Fgas in gas mixture times by barometric pressure

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8
Q

what are the two forms of oxygen being carried in the blood

A

dissolved
bound to haemoglobin

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9
Q

describe how dissolved oxygen is measured

A

clinically in an arterial blood sample

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10
Q

how much of oxygen in the blood is dissolved

A

only a small percentage

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11
Q

what is the amount of oxygen dissoved in the blood proportional to

A

partial pressure

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12
Q

how many ml of oxygen per 100ml of blood for each mmHg of PO2

A

0.003

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13
Q

how many litres of oxygen in the blood when the arterial blood has a partial pressure of 100mmHg

A

3ml

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14
Q

is the transport of oxygen in the dissolved form adequate for the body’s requirements

A

no

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15
Q

what is the typical partial pressure of oxygen in the blood for healthy individuals

A

100mmHg

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16
Q

which artery is usually used to provide a sample for calculating partial pressure

A

radial

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17
Q

what does the amount of oxygen dissolved in the blood determine

A

the partial pressure of oxygen in the blood

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18
Q

what is the minimum tissue requirement of oxygen at rest

A

250ml of oxygen a minute

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19
Q

how many litres of blood per minute at rest cardiac output

A

5 litres

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20
Q

what are the tissue requirements for oxygen during strenuous exercise

A

3000 ml oxygen per minute

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21
Q

what is haemoglobin

A

major transport molecule for oxygen found in red blood cells

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22
Q

describe the structure of haemoglobin

A

four heme groups joined to globin proteins.
two alpha and two beta chains

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23
Q

what is heme

A

iron porphyrin compound

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24
Q

what is found in each heme group

A

iron in reduced ferrous form Fe+++

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25
Q

what is the site of oxygen binding in haemoglobin

A

each ferrous molecule in the heme groups

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26
Q

how many haemoglobin molecules per red blood cells

A

280 million

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27
Q

why is it necessary that the binding and dissociation of oxygen from haemoglobin happens in milliseconds

A

the red blood cells are only in capillaries for one second

28
Q

what does the oxyhemoglobin dissociation curve show

A

the relationship between partial pressure of oxygen in the blood and the number of oxygen molecules bound to haemoglobin

29
Q

describe what you see

A

the line is a sigmoid curve. big clinical significance of this shape.
flat portion - in a normal healthy individual when the partial pressure of oxygen is 100mmHg, almost up to 100% of haemoglobin molecules are saturated. this means the blood is well oxygenated.
steep portion - partial pressure is dropping, but the haemoglobin saturation is stable. this does not change until the gradient of 60mmHg. when the partial pressure drops below this, there is fast dissociation of oxygen from haemoglobin to get more oxygen into the blood to oxygenate the tissues.

30
Q

how many oxygen molecules can bind to each haemoglobin molecules

A

four

31
Q

what does oxygen saturation refer to

A

the amount of oxygen bound to haemoglobin relative to maximal amount that can be bound

32
Q

how many ml of oxygen combines with a gram of haemglobin

A

1.39

33
Q

how many grams of haemoglobin per litre of blood

A

150g

34
Q

what is the average total oxygen capacity

A

211ml/s of oxygen per litre of blood

35
Q

what are used to measure oxygen saturation

A

pulse oximeters

36
Q

how do pulse oximeters work

A

they measure the ratio of absorption of red and infrared light by oxyHb and deoxyHb

37
Q

how many molecules of carbon dioxide are expired for every 100 molecules of oxygen by the lungs of a healthy person

A

80

38
Q

what is the respiratory exchange ratio

A

the ratio of expired carbon dioxide to oxygen uptake

39
Q

what is the respiratory exchange ratio in normal conditions

A

0.8

40
Q

what are the three forms that carbon dioxide travels the blood in

A

dissolved
bound to haemoglobin
converted to bicarbonate

41
Q

how mcuh carbon dioxide in the blood is dissolved

A

7%

42
Q

how much carbon dioxide in the blood is bound to haemoglobin

A

23%

43
Q

how much carbon dioxide in the blood is converted to bicarbonate

A

70%

44
Q

how much carbon dioxide is diffused into red blood cells

A

93%

45
Q

describe the reaction of carbon dioxide converting to bicarbonate

A

H2Co3 - carbonic acid
HCO3- - bicarbonate

46
Q

what determines the speed of bicarbonate production

A

concentration gradients

47
Q

what happens to carbon dioxide in systemic capillaries

A

rightward reaction to form bicarbonate from carbon dioxide. the carbon dioxide is expelled into the blood

48
Q

what happens to carbon dioxide in pulmonary capillaries

A

leftward reaction to form carbon dioxide from bicarbonate. the carbon dioxide is expelled into the alveoli

49
Q

what does the carbon dioxide to bicarbonate pathway have a key role in

A

regulation of hydrogen ions and in maintaining acid base balance in the body

50
Q

what can stabilise blood pH

A

changes in bicarbonate concentrations

51
Q

what makes the buffering reaction strong in the blood

A

high bicarbonate concentration

52
Q

what can regulate the acidity of the blood

A

ventilation to adjust the partial pressure of carbon dioxide OR using the kidneys to regulate the bicarbonate concentration

53
Q

what is the shape of the oxygen dissociation curve

A

sigmoid curve

54
Q

does partial pressure of oxygen have much of an impact on haemoglobin saturation

A

no

55
Q

what is the enzyme that converts carbon dioxide to carbonic acid

A

carbonic anhydrase

56
Q

what are some obstructive lung disease

A

emphysema
asthma

57
Q

what are some restrictive lung diseases

A

pulmonary fibrosis
neuromuscular diseases

58
Q

what is the percentage saturation of haemoglobin when PO2 is 10mmHg

A

10%

59
Q

what is the percentage saturation of haemoglobin when PO2 is 20mmHg

A

35%

60
Q

what is the percentage saturation of haemoglobin when PO2 is 30mmHg

A

60%

61
Q

what is the percentage saturation of haemoglobin when PO2 is 40mmHg

A

75%

62
Q

what is the percentage saturation of haemoglobin when PO2 is 50mmHg

A

80%

63
Q

what is the percentage saturation of haemoglobin when PO2 is 60mmHg

A

90%

64
Q

what is the percentage saturation of haemoglobin when PO2 is 70mmHg

A

90%

65
Q

what is the percentage saturation of haemoglobin when PO2 is 80mmHg+

A

98%

Human Systems and Anatomy (54 decks)

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