Lectures 16 & 17: Capnography, Equilibration, Hgb (Exam III) Flashcards

1
Q

What is the solubility coefficient of O₂?

Give answer per dL of solution

A

0.003 mLO₂/ mmHg PO₂ / dL of blood

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2
Q

Calculate how much O₂ is dissolved per deciliter of arterial blood.

A

0.3 mL O₂ / dL of blood

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3
Q

Calculate how much O₂ is dissolved per deciliter of venous blood.

A

(0.003 mL O₂ ÷ 100mL blood x PO₂) x 40 mmHg =

0.12 mL O₂ / dL of blood

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4
Q

How much O₂ is dropped off at the tissues per deciliter every minute?

A

Δ = 5mLO₂ /dL blood

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5
Q

Given a partial pressure of 100mmHg, we should be able to dissolve a max of ____ mL of O₂ in a dL of blood

A

0.3

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6
Q

How many O₂ does one Hb molecule carry?

A

4 O₂ molecules.

I assume this means 8 total oxygen atoms?

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7
Q

How many mL of O₂ can Hb (hemoglobin) carry?

A

1.34 mL O₂ /gram Hb

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8
Q

How many grams/dL of Hb do we have?

A

15 g/dL

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9
Q

Differentiate Deoxyhemoglobin and Oxyhemoglobin.

A
  • Deoxyhemoglobin = Hb + O₂
  • Oxyhemoglobin = HbO₂
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10
Q

What factors/conditions would accelerate the formation of deoxyhemoglobin?

A
  • ↓ pH
  • ↑ H⁺
  • ↑ CO₂
  • ↑ Temp
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11
Q

What factors/conditions would accelerate the formation of oxyhemoglobin?

A
  • ↑ pH
  • ↓ H⁺
  • ↓ CO₂
  • ↓ Temp
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12
Q

What is the formula for determining max carrying capacity?

A
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13
Q

What would be the carrying capacity of someone who had a hemoglobin of 10 g/dL and Hb carrying capacity of 1.2 mLO₂ /gHb ?

A

12 mLO₂ / dL of blood

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14
Q

Will decreased Hb (hemoglobin) result in an increase or decrease to cardiac workload?

A

↑Hb = ↑ cardiac workload

More Hb = increased viscosity = harder for the heart to pump.

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15
Q

At what partial pressure should our Hb molecules be completely saturated?

A

100 mmHg O₂

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16
Q

According to graph below, for normal blood, when would one see a carrying capacity of 15mLo2/dL ?

A

PO₂ = 40mmHg = 15 mLO₂/dL

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17
Q

What effect(s) does CO have on Hb molecules?

A
  • CO becomes bound and “sticks” (has a high affinity and won’t unbind from Hb molecule).
  • CO makes O₂ molecules have a higher affinity so they won’t be unbound as easily as normal.
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18
Q

Based on the graph below, when would we expect an SaO₂ of 75% ?

A

At 15 mLO₂/dL (100% of SaO₂ occurs at 20 mLO₂/dL)

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19
Q

What is normal SaO₂ at a PO₂ of 100mmHg?
Why?

A

SaO₂ = 97.4%

Lower than 100% due to presence of methemoglobin and venous bronchiolar drainage into arterial supply.

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20
Q

What occurs with Hb as as PO₂ decreases?

A

Decreasing PO₂ allow for easier unloading of O₂ from Hb due to decreased affinity.

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21
Q

What is CaO₂ ?

A

Content of oxygen in the arterial system in mL.

Hb-bound O₂ and PaO₂

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22
Q

What is CvO₂ ?

A

Content of oxygen in the venous system in mL.

Hb-bound O₂ and PvO₂

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23
Q

What is the CaO₂ assuming an SaO₂ of 97.4%, and PO₂ of 100mmHg?

A

19.88mL O₂ /dL blood

(dissolved: 0.3 mLO₂) + (Hb-bound 19.58 mLO₂)

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24
Q

What is the CvO₂ assuming an SvO₂ of 75%, and PvO₂ of 40mmHg?

A

15.195 mLCO₂ / dL blood

Dissolved: 0.12 mLCO₂
Bound: 15.075 mLCO₂

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25
Q

needs work

A

needs work

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26
Q

How does the affinity of HbF (fetal hemoglobin) compare to that of HbA (adult hemoglobin) ?

A

HbF exhibits much greater affinity for O₂ than HbA

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27
Q

Why does HbF have a greater affinity for O₂ than HbA?

A

Mechanism to ensure adequate oxygen delivery to the baby.

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28
Q

PaO₂ can vary from ___ to ___ without much change in Hb saturation.

A

70 to 100

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29
Q

What is 2,3 DPG?
What are the various names for it?

Also known as 2,3 BPG

A

Product of metabolism (produced by RBC during glycolysis)

  • 2,3 Biphosphoglycerate
  • 2,3 Diphosphoglycerate
  • Biphosphoglyceric acid
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30
Q

What cells produce a lot of 2,3 DPG?

A

RBCs

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31
Q

Blood products will have ________ 2,3 DPG levels from storage.

A

decreased

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32
Q

What factors/conditions will cause a rightward shift in the oxyhemoglobin dissociation curve?

A
  • ↓ pH
  • ↑ H⁺
  • ↑ CO₂
  • ↑ 2,3 DPG
  • ↑ Temp
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33
Q

The Bohr effect is related to what concept?

A

Oxyhemoglobin dissociation curve (O₂ affinity)

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34
Q

What molecule besides Hb has reversible O₂ carrying capabilities?

A

Myoglobin

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35
Q

Where is myoglobin found?

A

skeletal muscles

particularly ones that see a lot of use like the calf muscles

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36
Q

What element is pertinent in myoglobin and hemoglobin capabilities to carry O₂ ?

A

Fe⁺⁺

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37
Q

What sort of affinity for O₂ would myoglobin exhibit compared to Hb?

A

Myoglobin = ↑O₂ affinity

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38
Q

What things will decrease measured SvO₂ ?

A
  • ↑O₂ consumption
  • Diet pills
  • ↓O₂ delivery (↓CO)
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39
Q

What things will increase measured SvO₂ ?

A
  • Poor O₂ extraction
  • ↓ metabolic activity
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40
Q

If someone is young and healthy, SvO₂ should be ___% or greater.

A

70

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41
Q

What does P50 mean?

A

PO₂ that correlates with 50% O₂ saturation.

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42
Q

What concept does the graph below convey?

A

Differing affinities for O₂ between venous and arterial blood based on the P50 metric.

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43
Q

Which of the lines on the graph below are venous and arterial?

A
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44
Q

What is the P50 of arterial blood?

A

Pa50 = 26.5mmHg

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45
Q

What is the P50 of venous blood?

A

Pa50 = 32mmHg

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46
Q

Is venous blood or arterial blood generally warmer?

A

Venous

47
Q

Is venous blood generally more or less “acidotic” than arterial blood?

A

more acidic (↓pH)

48
Q

Where is carbon dioxide stored in the blood?

Give percentages as well.

A
  • 90% as HCO₃⁻
  • 5% as Carbamino groups
  • 5% dissolved as PCO₂
49
Q

What is the solubility coefficient of CO₂ ?

A

0.06 mLCO₂ / mmHg PCO₂ / dL of blood

50
Q

How much CO₂ is dissolved in arterial blood?

A

0.06 mLCO₂ x 40 mmHg (PCO₂) = 2.4 mLCO₂ per dL of blood

51
Q

How much CO₂ is dissolved in venous blood?

A

0.06 mLCO₂ x 45 mmHg (PCO₂) = 2.7 mLCO₂ per dL of blood

52
Q

What is CaCO₂ ?

A

Measurement of the content (mL) of CO₂ gas in arterial blood.

53
Q

What is CvCO₂ ?

A

Measurement of the content (mL) of CO₂ gas in venous blood.

54
Q

What graph is depicted below?

A

CO₂ Dissociation Curve

55
Q

What is the CaCO₂ based on the graph below?

A

CaCO₂ = 48 mLCO₂/dL

56
Q

What is the CvCO₂ based on the graph below?

A

CaCO₂ = 52.5 mLCO₂/dL

57
Q

Why can venous blood carry more CO₂ than arterial blood?

A

Venous blood has less O₂ and thus has room to carry CO₂.
(Haldane effect)

58
Q

What is the Δ of CO₂ in mL/dL in from venous to arterial?

A

CO₂ Δ = 4.5 mL/dL

59
Q

T/F… O₂ content will not affect CO₂ affinity for Hb.

A

False. O₂ content influences CO₂ affinity for Hb.

↓O₂ = ↑CO₂ affinity

60
Q

What enzyme hydrolyzes H₂CO₃ ?

What are the products?

A
  • Carbonic anhydrase
  • H₂O and CO₂
61
Q

What products can form from H₂CO₃ ?

A

HCO₃⁻ and H⁺

62
Q

What enzyme hydrolyzes H₂CO₃ ?

A
63
Q

HCO₃⁻ moves from _____ to the _____ at the tissue level.

A

RBCs to the plasma

64
Q

What moves HCO₃⁻ to the plasma at the capillaries?

A

HCO₃⁻ / Cl⁻ antiporter

65
Q

What occurs with the H⁺ that is a product of H₂CO₃ splitting?

A

The H⁺ binds to HbO₂ (oxyhemoglobin) to produce → O₂ and HHb (deoxyhemoglobin)

66
Q

What occurs with the H⁺ that is a product of H₂CO₃ splitting?

A

The H⁺ binds to HbO₂ (oxyhemoglobin) to produce → O₂ and HHb (deoxyhemoglobin)

67
Q

Between Hb and HbO₂ , which molecule is more basic?
What is the consequence of this?

A

Hb is more basic and therefore accepts a H⁺ easier.

68
Q

Between HHb and HbO₂ , which molecule is more acidic?
What is the consequence of this?

A

HbO₂ is more acidic and therefore donates a H⁺ easier.

69
Q

What occurs with HHb (deoxyhemoglobin) after is splits from its O₂ molecule?

A

HHb binds with CO₂ forming a carbamino compound.

70
Q

What occurs with CO₂ and O₂ transport at the alveoli?

A

Everything switches

71
Q

At what time does O₂ reach alveolar equilibration?

A

0.25s to reach 104 mmHg

72
Q

At what time does O₂ reach alveolar equilibration?

A

0.25s

73
Q

What is the PO₂ at the beginning of this graph?
The end?

A

Entering capillary = 40mmHg
Leaving capillary = 104 mmHg

74
Q

Which of the lines below would be representative of perfusion-limited gas exchange?
What is a perfusion-limited gas?

A
  • N₂O and O₂ (blue and black)
  • ↑CO = ↑ absorption of the gas
75
Q

Which of the lines below would be representative of diffusion-limited gas exchange?
What is a diffusion-limited gas?

A
  • Red
  • Equilibration of gas is limited by a diffusion barrier (i.e. ↑CO won’t help)
76
Q

CO exhibits _______ ______ gas exchange.

A

Diffusion-limited

77
Q

What effect would pulmonary edema have on gas diffusion?

A

Pulmonary edema would increase the H₂O barrier in the alveolus and increase time to O₂ equilibration.

78
Q

What carrier protein carries N₂O ?

A

Trick question. N₂O just hangs out in the plasma.

79
Q

What gas (other than O₂ ) takes 0.25s to equilibrate as well?

A

CO₂

80
Q

How quickly does N₂O equilibrate?

A

10% of the way through the capillary. (≈ .08s)

81
Q

Why does N₂O move to air filled spaces?

A

Because it is moving down its concentration gradient.

82
Q

When does O₂ become a diffusion limited gas?

A

When movement is 1/8 that of normal.

83
Q

What is Ficks Law?

A

gas = [A x D x ( ΔP )] ÷ T

  • A = Surface area
  • D = Diffusivity
  • T = Barrier Thickness
84
Q

What factors, if increased, will increase gas diffusion?

A

A (surface area)
D (Diffusivity)
Δ P

85
Q

What factor(s), if increased, will decrease gas diffusion?

A

T (thickness of alveolar barrier)

86
Q

What is the formula for Diffusivity?

A

D = Solubility ÷ √MW

87
Q

Increased H₂O solubility makes a gas ____ diffusible.

A

more

88
Q

A larger molecular weight makes a gas ____ diffusible.

A

less

89
Q

What is the molecular weight of O₂ ?

A

32

90
Q

What is the molecular weight of CO₂ ?

A

44

91
Q

What is HbA1c ?
What does it measure?
What occurs with it in regards to O₂ delivery?

A
  • Hgb w/ glucose stuck to the 1c position.
  • Measurement of chronic glucose levels.
  • Hb becomes less capable of O₂ delivery (irreversible and requires death of RBC)
92
Q

Which form of iron attached to hemoglobin can bind reversibly to O₂ and CO₂ ?

A

Fe⁺⁺ (Ferrous iron)

93
Q

Which form of iron attached to hemoglobin is dysfunctional in its ability to carry O₂ and CO₂ ?

A

Fe⁺⁺⁺ (Ferritic iron)

94
Q

What stimulates the transition of ferrous iron to ferritic iron?

A

Free radical formation and oxidative stress

(sepsis, MODS, etc)

95
Q

What enzyme reduces ferritic iron to ferrous iron?

A

Fe⁺⁺⁺ → Methemoglobin Reductase → Fe⁺⁺

96
Q

What things potentiate methemoglobin reductase?

A
  • NO donors
  • Sulfonamides

this needs verification

97
Q

Fe⁺⁺ has become Fe⁺⁺⁺. Was Fe⁺⁺ oxidized or reduced?

A

Oxidized (+ charge added)

98
Q

What chains compose HbA?

A

2 α-chains and 2 β-chains

99
Q

What chains compose HbF?

A

2 α-chains and 2 γ-chains

100
Q

What part of the Hb molecule is dysfunctional in sickle cell disease?

A

β-chains are “sickled”

101
Q

What chains compose HbS (sickled Hb) ?

A

2 α-chains and 2 βS-chains

βS-chains are sickled and dysfunctional

102
Q

Differentiate sickle cell disease and sickle cell trait.

A
  • Sickle-cell disease: 2 parents, 2 βS-chains, severe s/s.
  • Sickle-cell trait: 1 parent, 1 βS-chains, milder s/s.
103
Q

What shape does the HbS take after dropping off O₂ ?

A

Sickle shape

104
Q

Sickled Hb RBCs get stuck in __________ due to an inability to ________.

A

Capillaries; deform

105
Q

What possible evolutionary benefit developed from sickle cell trait?

A

Resistance to malaria

106
Q

What are the signs and symptoms of sickle cell disease?

A
  • Vasculature remodels (to accommodate sickled RBCs)
  • Pain (from local tissue ischemia)
  • Hemolytic anemia (RBCs are constantly lysing)
107
Q

What is a normal RBC lifetime?
What about a sickled RBC?

A
  • Normal: 120 days
  • Sickled: 20 days
108
Q

How can Sickle-Cell Disease/Trait be treated?

A
  • Transfusions (replace w/ “better” blood)
  • Hydroxyurea: Induce production of HbF to replace HbS
109
Q

What is the partial pressure of CO₂ in Ē (mixed expired air) ?

Find PCO₂ of Ē

A

PCO₂ of VD = 0
PCO₂ of VA = ?

40mmHg ÷ 760mmHg → [CO₂] of 0.05263 → 350mls (VA) x 0.05263 = 18.42 mLs CO₂ per breath.

18.42 mLs CO₂ ÷ 500mLs = 0.03684 → 760mmHg x 0.03684 = 27.998mmHg

PCO₂ of Ē = 27.998mmHg

110
Q

What is the PO₂ of Ē ?

A

120 mmHg

PO₂ of Ē is higher than PAO₂ due to addition of VD air.

111
Q

What is the Haldane effect related to?

A

CO₂ quantities and transport.
Allows blood to load more CO2 at the tissues (where there’s more deoxyhemoglobin) and unload CO2 in lung (where there’s more oxyhemoglobin) p315 Lange

needs verification

112
Q

What is the Bohr effect related to?

A

O₂ carrying capacity

needs verification

113
Q

What is Henry’s law related to?

A

Solubility and dissolved gasses

needs verification

114
Q

Low CO will result in ____________ O₂ extraction from the tissues.

A

Increased

↓CO = ↓SvO₂