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Physiology > Respiratory IV Transport of O2 and CO2 > Flashcards

Respiratory IV Transport of O2 and CO2 Flashcards

1
Q

how is oxygen carried physically and chemically in the body

A

physically dissolved in blood and chemically combined to hemoglobin

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2
Q

how is carbon dioxide physically and chemically carried in the body

A

physically dissolved in blood, chemically combined to blood proteins as carbamino compounds and as bicarbonate

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3
Q

what do the partial pressure of the gases include

A

the gases that are dissolved in the plasma

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4
Q

what happens to the gradient when cells utilize more oxygen than normal

A

the gradient increases which increases flow of oxygen from the blood to the tissues

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5
Q

what is the tissue PO2 a function of

A

-the rate of O2 transport to the tissues in blood (blood flow)
- the rate at which the tissues use O2

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6
Q

what does increased blood flow and/or increased metabolism result in with O2

A

more O2 delivery to the tissues

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7
Q

what is the pressure in arteries of O2, CO2, and SO2

A

-O2: 95
-CO2: 40
- SO2: 97%

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8
Q

what is the pressure in the capillaries of O2 and CO2

A

-O2: 40
CO2: 46

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9
Q

what is the pressure in the veins of O2, CO2, and SO2

A

-O2: 40
-CO2: 46
-SO2: 75%

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10
Q

without hemoglobin what would CO need to be in L/min to transport sufficient oxygen to meet the needs of the tissues at rest

A

83.3 L/min

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11
Q

how much of the total oxygen content is dissolved in plasma

A

2%

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12
Q

how much O2 reversibly binds to hemoglobin inside of the RBC

A

98%

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13
Q

describe the hemoglobin molecule

A

2 alpha subunits and 2 beta subunits and each bind 1 molecule of O2

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14
Q

what state must iron be in to bind O2

A

ferrous state

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15
Q

what does the amount of oxygen bound to hemoglobin depend on

A

-plasma O2
- number of binding sites in RBCs

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16
Q

what does the number of binding sites in RBCs depend on

A

the Hb amount per RBC

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17
Q

how many Hb molecules does 1 RBC contain

A

1 million

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18
Q

what is the concentration of oxygen in the arterial blood (definition)

A

ml of O2 carried by oxyhemoglobin plus ml of O2 carried dissolved in plasma

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19
Q

what is the average g of Hb / 100 mL of blood

A

15 g Hb/100 mL blood

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20
Q

what is the average partial pressure of oxygen in arterial blood

A

95 mmHg

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21
Q

what is the average CaO2 ( number)

A

19.782 ml O2/100 mL blood

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22
Q

what does 2,3-BPG do

A

binds to beta subunits of deoxy hemoglobin and decreases its O2 affinity which causes more oxygen unloading

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23
Q

what is positive cooperativity

A

at a high PO2 hemoglobin’s affinity for O2 is highest

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24
Q

when does a major drop off in % O2 saturation of hemoglobin occur

A

60 mmHg

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25
Q

what is the bohr effect

A

the oxyhemoglobin dissociation curve shifts to the right

26
Q

what is a right shift/bohr effect caused by

A

-increased H+ ions
- increased CO2
- increased temperature
- increased BPG

27
Q

what does a right shift in the oxyhemoglobin dissociation curve indicate

A

decreased affinity between hemoglobin and oxygen

28
Q

when do levels of 2,3- BPG increase

A

with exercise, hypoxia from high altitude, pregnancy, and chronic lung disease

29
Q

what is the normal blood pH

A

7.4

30
Q

what is a left shift in the oxyhemoglobin dissociated curve caused by

A
  • decreased PCO2
  • increased pH
  • decreased temperature
  • decreased 2,3- BPG
31
Q

what does a left shift indicate about oxygen/Hb affinity

A
  • increased affinity
  • O2 is less likely to dissociate from Hb
32
Q

how much of a greater affinity does CO have for Hb than O2 does to Hb

A

250x

33
Q

what is the effect of CO bound to Hb

A

increased Hb’s affinity for O2 (left ward shift in curve)

34
Q

if CaO2 is greatly reduced, what happens to PaO2

A

could be normal

35
Q

what is the treatment for CO poisoning

A

-pure oxygen
- 5% CO2

36
Q

what is the common presentation of CO poisoning

A

-cherry red skin
- flu like symptoms
- headache
- neurologic symptoms

37
Q

what are the 3 variants of Hb

A

-methemoglobin
- hemoglobin F ( fetal)
- hemoglobin S (sickle cell)

38
Q

what happens in methemoglobin

A

-heme with Fe3+ (ferric) has lower O2 affinity and causes heme groups in the same Hb molecule with heme in the Fe2+ (ferrous) state to have higher affinity for bound O2 so net effect is less O2 release from Hb and less delivery to tissues

39
Q

what can methemoglobin occur due to

A

G6PDH deficiency or exposure to local anesthetics such as prilocaine or benzocaine

40
Q

describe the structure of hemoglobin F

A

2 alpha chains and 2 gamma chains

41
Q

describe the affinity of hemoglobin F to O2

A

higher affinity for oxygen than adult Hb because it doesnt contain the beta chain that binds to 2,3-BPG

42
Q

describe the structure of Hb S and what causes it

A

-normal alpha and beta units
- caused by one amino acid change
- when deoxygenated, RBCs form sickle shapes and obstruct small vessels

43
Q

describe Hb S affinity for O2 compared to normal adult Hb

A

O2 has lower affinity

44
Q

what is the oxygen content in methemoglobin compared to normal oxyhemoglobin

A

decreased by 50% so about 10

45
Q

what is hypoxemia

A

low PaO2

46
Q

what is hypoxia

A

low tissue O2

47
Q

what causes hypoxemia

A

-decreased FiO2
-hypoventilation
- diffusion defects
- V/Q defects

48
Q

describe the A-a gradient in decreased FiO2, hypoventilation, diffusion defects, and V/Q defects

A

-decreased FiO2: normal
-hypoventilation: normal
- diffusion defects: increased
- V/Q defects: increased

49
Q

when is supplemental O2 helpful in hypoxemia causes

A

in every case

50
Q

what can hypoxia be caused by

A

hypoxemia, decreased cardiac output, anemia

51
Q

what are the PCO2 values in the alveoli, arteries, capillaries and veins

A
  • alveoli: 40
    -arteries: 40
    -capillaries: 46
    0veins: 46
52
Q

does hemoglobin transport CO2

A

yes

53
Q

what can CO2 be transported as in the blood and what are the percentages of each

A

-dissolved CO2: 7%
- carbamino-hemoglobin: 23%
- bicarbonate: 70%

54
Q

what is the volume of transport of CO2 in the blood

A

4 ml CO2 / 100 mL blood

55
Q

which is the slowest of the transport mechanisms of CO2 in blood

A

carbaminohemoglobin

56
Q

which is the fastest of the transport mechanisms of CO2 in blood

A

bicarbonate

57
Q

describe the carbaminohemoglobin transport mechanism

A

CO2 forms a loose, reversible bond with hemoglobin on terminal amine groups

58
Q

describe the bicarbonate transport mechanism

A

In RBCs, carbonic anhydrase rapidly forms carbonic acid from H2O and CO2 which in turn dissociates into H+ and HCO3-
- H+ combines with hemoglobin for buffering and HCO3- moves into plasma in exchange for Cl-

59
Q

what is the haldane effect in systemic capillaries

A

deoxygenated Hb promotes increased binding of CO2 to Hb

60
Q

what would happen to PaCO2 if there were no carbonic anhydrase

A

it would increase by double

61
Q

what is the effect of CO2 with Hb at lower O2 concentrations

A

CO2 is more likely to combine with Hb and Hb buffers more H+

62
Q

what is the haldane effect in pulmonary capillaries

A

oxygenated Hb promotes dissociation of CO2 from Hb

Physiology (41 decks)

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