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
2
Q
Calculate how much O₂ is dissolved per deciliter of arterial blood.
A
0.3 mL O₂ / dL of blood
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
4
Q
How much O₂ is dropped off at the tissues per deciliter every minute?
A
Δ = 5mLO₂ /dL blood
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
6
Q
How many O₂ does one Hb molecule carry?
A
4 O₂ molecules.
I assume this means 8 total oxygen atoms?
7
Q
How many mL of O₂ can Hb (hemoglobin) carry?
A
1.34 mL O₂ /gram Hb
8
Q
How many grams/dL of Hb do we have?
A
15 g/dL
9
Q
Differentiate Deoxyhemoglobin and Oxyhemoglobin.
A
- Deoxyhemoglobin = Hb + O₂
- Oxyhemoglobin = HbO₂
10
Q
What factors/conditions would accelerate the formation of deoxyhemoglobin?
A
- ↓ pH
- ↑ H⁺
- ↑ CO₂
- ↑ Temp
11
Q
What factors/conditions would accelerate the formation of oxyhemoglobin?
A
- ↑ pH
- ↓ H⁺
- ↓ CO₂
- ↓ Temp
12
Q
What is the formula for determining max carrying capacity?
A
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
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.
15
Q
At what partial pressure should our Hb molecules be completely saturated?
A
100 mmHg O₂
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
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.
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)
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.
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.
21
Q
What is CaO₂ ?
A
Content of oxygen in the arterial system in mL.
Hb-bound O₂ and PaO₂
22
Q
What is CvO₂ ?
A
Content of oxygen in the venous system in mL.
Hb-bound O₂ and PvO₂
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)
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
25
*needs work*
*needs work*
26
How does the affinity of HbF (fetal hemoglobin) compare to that of HbA (adult hemoglobin) ?
HbF exhibits much greater affinity for O₂ than HbA
27
Why does HbF have a greater affinity for O₂ than HbA?
Mechanism to ensure adequate oxygen delivery to the baby.
28
PaO₂ can vary from ___ to ___ without much change in Hb saturation.
70 to 100
29
What is 2,3 DPG?
What are the various names for it?
*Also known as 2,3 BPG*
Product of metabolism (produced by RBC during glycolysis)
- 2,3 Biphosphoglycerate
- 2,3 Diphosphoglycerate
- Biphosphoglyceric acid
30
What cells produce a lot of 2,3 DPG?
RBCs
31
Blood products will have ________ 2,3 DPG levels from storage.
decreased
32
What factors/conditions will cause a rightward shift in the oxyhemoglobin dissociation curve?
- ↓ pH
- ↑ H⁺
- ↑ CO₂
- ↑ 2,3 DPG
- ↑ Temp
33
The Bohr effect is related to what concept?
Oxyhemoglobin dissociation curve (O₂ affinity)
34
What molecule besides Hb has reversible O₂ carrying capabilities?
Myoglobin
35
Where is myoglobin found?
skeletal muscles
*particularly ones that see a lot of use like the calf muscles*
36
What element is pertinent in myoglobin and hemoglobin capabilities to carry O₂ ?
Fe⁺⁺
37
What sort of affinity for O₂ would myoglobin exhibit compared to Hb?
Myoglobin = ↑O₂ affinity
38
What things will decrease measured SvO₂ ?
- ↑O₂ consumption
- Diet pills
- ↓O₂ delivery (↓CO)
39
What things will increase measured SvO₂ ?
- Poor O₂ extraction
- ↓ metabolic activity
40
If someone is young and healthy, SvO₂ should be ___% or greater.
70
41
What does P50 mean?
PO₂ that correlates with 50% O₂ saturation.
42
What concept does the graph below convey?
Differing affinities for O₂ between venous and arterial blood based on the P50 metric.
43
Which of the lines on the graph below are venous and arterial?
44
What is the P50 of arterial blood?
Pa50 = 26.5mmHg
45
What is the P50 of venous blood?
Pa50 = 32mmHg
46
Is venous blood or arterial blood generally warmer?
Venous
47
Is venous blood generally more or less "acidotic" than arterial blood?
more acidic (↓pH)
48
Where is carbon dioxide stored in the blood?
*Give percentages as well.*
- 90% as HCO₃⁻
- 5% as Carbamino groups
- 5% dissolved as PCO₂
49
What is the solubility coefficient of CO₂ ?
0.06 mLCO₂ / mmHg PCO₂ / dL of blood
50
How much CO₂ is dissolved in arterial blood?
0.06 mLCO₂ x 40 mmHg (PCO₂) = **2.4 mLCO₂ per dL of blood**
51
How much CO₂ is dissolved in venous blood?
0.06 mLCO₂ x 45 mmHg (PCO₂) = **2.7 mLCO₂ per dL of blood**
52
What is CaCO₂ ?
Measurement of the content (mL) of CO₂ gas in arterial blood.
53
What is CvCO₂ ?
Measurement of the content (mL) of CO₂ gas in venous blood.
54
What graph is depicted below?
CO₂ Dissociation Curve
55
What is the CaCO₂ based on the graph below?
CaCO₂ = 48 mLCO₂/dL
56
What is the CvCO₂ based on the graph below?
CaCO₂ = 52.5 mLCO₂/dL
57
Why can venous blood carry more CO₂ than arterial blood?
Venous blood has less O₂ and thus has room to carry CO₂.
(Haldane effect)
58
What is the Δ of CO₂ in mL/dL in from venous to arterial?
CO₂ Δ = 4.5 mL/dL
59
T/F... O₂ content will not affect CO₂ affinity for Hb.
False. O₂ content influences CO₂ affinity for Hb.
↓O₂ = ↑CO₂ affinity
60
What enzyme hydrolyzes H₂CO₃ ?
What are the products?
- *Carbonic anhydrase*
- H₂O and CO₂
61
What products can form from H₂CO₃ ?
HCO₃⁻ and H⁺
62
What enzyme hydrolyzes H₂CO₃ ?
63
HCO₃⁻ moves from _____ to the _____ at the tissue level.
RBCs to the plasma
64
What moves HCO₃⁻ to the plasma at the capillaries?
HCO₃⁻ / Cl⁻ antiporter
65
What occurs with the H⁺ that is a product of H₂CO₃ splitting?
The H⁺ binds to HbO₂ (oxyhemoglobin) to produce → O₂ and HHb (deoxyhemoglobin)
66
What occurs with the H⁺ that is a product of H₂CO₃ splitting?
The H⁺ binds to HbO₂ (oxyhemoglobin) to produce → O₂ and HHb (deoxyhemoglobin)
67
Between Hb and HbO₂ , which molecule is more basic?
What is the consequence of this?
Hb is more basic and therefore accepts a H⁺ easier.
68
Between HHb and HbO₂ , which molecule is more acidic?
What is the consequence of this?
HbO₂ is more acidic and therefore donates a H⁺ easier.
69
What occurs with HHb (deoxyhemoglobin) after is splits from its O₂ molecule?
HHb binds with CO₂ forming a **carbamino** compound.
70
What occurs with CO₂ and O₂ transport at the alveoli?
**Everything switches**
71
At what time does O₂ reach alveolar equilibration?
0.25s to reach 104 mmHg
72
At what time does O₂ reach alveolar equilibration?
0.25s
73
What is the PO₂ at the beginning of this graph?
The end?
Entering capillary = 40mmHg
Leaving capillary = 104 mmHg
74
Which of the lines below would be representative of perfusion-limited gas exchange?
What is a perfusion-limited gas?
- N₂O and O₂ (blue and black)
- ↑CO = ↑ absorption of the gas
75
Which of the lines below would be representative of diffusion-limited gas exchange?
What is a diffusion-limited gas?
- Red
- Equilibration of gas is limited by a diffusion barrier (i.e. ↑CO won't help)
76
CO exhibits _______ ______ gas exchange.
Diffusion-limited
77
What effect would pulmonary edema have on gas diffusion?
Pulmonary edema would increase the H₂O barrier in the alveolus and increase time to O₂ equilibration.
78
What carrier protein carries N₂O ?
Trick question. N₂O just hangs out in the plasma.
79
What gas (other than O₂ ) takes 0.25s to equilibrate as well?
CO₂
80
How quickly does N₂O equilibrate?
10% of the way through the capillary. (≈ .08s)
81
Why does N₂O move to air filled spaces?
Because it is **moving down its concentration gradient**.
82
When does O₂ become a diffusion limited gas?
When movement is 1/8 that of normal.
83
What is Ficks Law?
**V̇gas = [A x D x ( ΔP )] ÷ T**
- A = Surface area
- D = Diffusivity
- T = Barrier Thickness
84
What factors, if increased, will increase gas diffusion?
A (surface area)
D (Diffusivity)
Δ P
85
What factor(s), if increased, will decrease gas diffusion?
T (thickness of alveolar barrier)
86
What is the formula for Diffusivity?
D = Solubility ÷ √MW
87
Increased H₂O solubility makes a gas ____ diffusible.
more
88
A larger molecular weight makes a gas ____ diffusible.
less
89
What is the molecular weight of O₂ ?
32
90
What is the molecular weight of CO₂ ?
44
91
What is HbA1c ?
What does it measure?
What occurs with it in regards to O₂ delivery?
- 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
Which form of iron attached to hemoglobin can bind reversibly to O₂ and CO₂ ?
Fe⁺⁺ (Ferrous iron)
93
Which form of iron attached to hemoglobin is dysfunctional in its ability to carry O₂ and CO₂ ?
Fe⁺⁺⁺ (Ferritic iron)
94
What stimulates the transition of ferrous iron to ferritic iron?
Free radical formation and oxidative stress
(*sepsis, MODS, etc*)
95
What enzyme reduces ferritic iron to ferrous iron?
Fe⁺⁺⁺ → *Methemoglobin Reductase* → Fe⁺⁺
96
What things potentiate methemoglobin reductase?
- NO donors
- Sulfonamides
*this needs verification*
97
Fe⁺⁺ has become Fe⁺⁺⁺. Was Fe⁺⁺ oxidized or reduced?
Oxidized (+ charge added)
98
What chains compose HbA?
2 α-chains and 2 β-chains
99
What chains compose HbF?
2 α-chains and 2 γ-chains
100
What part of the Hb molecule is dysfunctional in sickle cell disease?
β-chains are "sickled"
101
What chains compose HbS (sickled Hb) ?
2 α-chains and 2 βS-chains
*βS-chains are sickled and dysfunctional*
102
Differentiate sickle cell disease and sickle cell trait.
- Sickle-cell disease: 2 parents, 2 βS-chains, severe s/s.
- Sickle-cell trait: 1 parent, 1 βS-chains, milder s/s.
103
What shape does the HbS take **after** dropping off O₂ ?
Sickle shape
104
Sickled Hb RBCs get stuck in __________ due to an inability to ________.
Capillaries; deform
105
What possible evolutionary benefit developed from sickle cell trait?
Resistance to malaria
106
What are the signs and symptoms of sickle cell disease?
- Vasculature remodels (to accommodate sickled RBCs)
- Pain (from local tissue ischemia)
- Hemolytic anemia (RBCs are constantly lysing)
107
What is a normal RBC lifetime?
What about a sickled RBC?
- Normal: 120 days
- Sickled: 20 days
108
How can Sickle-Cell Disease/Trait be treated?
- Transfusions (replace w/ "better" blood)
- **Hydroxyurea**: Induce production of HbF to replace HbS
109
What is the partial pressure of CO₂ in Ē (mixed expired air) ?
*Find PCO₂ of Ē*
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
What is the PO₂ of Ē ?
120 mmHg
*PO₂ of Ē is higher than PAO₂ due to addition of VD air*.
111
What is the Haldane effect related to?
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
What is the Bohr effect related to?
O₂ carrying capacity
*needs verification*
113
What is Henry's law related to?
Solubility and dissolved gasses
*needs verification*
114
Low CO will result in ____________ O₂ extraction from the tissues.
Increased
↓CO = ↓SvO₂
