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Physiology Part 2 > Lec 36 Ox Transport and Delivery > Flashcards

Lec 36 Ox Transport and Delivery Flashcards

1
Q

What percent of O2 in blood is dissolved free in solution?

A

2% of total O2

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2
Q

What is henry’s law?

A

Cx = Px * Solubility

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3
Q

What is solubility of O2?

A

0.0003 mL O2/100 mL blood / mmHg

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4
Q

What is conc of dissolved O2 when arterial PO2 is 100 mmHg?

A

0.3 mL O2/ 100 mL blood

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5
Q

What is O2 consumption of a person at rest?

A

250 mL O2/min

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6
Q

True or false: O2 deliver base on dissolved O2 alone is sufficient to meet tissue demands

A

false: dissolved O2 alone is too low/insufficient

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7
Q

What are the forms of O2 in blood?

A

2% free dissolved

98% bound to HbA

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8
Q

How much of O2 in blood is bound to HbA?

A

98%

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9
Q

How many O2 bind each HbA?

A
  • each molec HbA has 4 subunits [2 a and 2 B]
  • each subunit binds one molec O2
  • each Hb binds 4 molec O2
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10
Q

How many mL O2 can 1 gm of HbA bind when 100% saturated?

A

1.34 mL O2

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11
Q

What is normal Hb concentration of blood?

A

15 gm/dL

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12
Q

What is normal O2 binding capacity of blood?

A

15 gm/dL * 1.34 mL = 20.1 mL O2/100 mL blood

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13
Q

What is O2 content of blood?

A

O2 content = actual amt O2 in mL/100 mL bood

= O2 bound to HbA + dissolved O2

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14
Q

What is equation for O2 bound to HbA?

A

O2 bound to HbA = O2 binding capacity * percent saturation

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15
Q

What is equation for O2 binding capacity?

A

O2 binding capacity = Hb conc * 1.34 mL O2/gm Hb at 100% saturation

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16
Q

What is the equation for O2 delivery to tissues?

A

O2 delivery = blood flow * O2 content of blood

in more detail:
O2 delivery = CO [Q] * (Oxygenated Hb + dissolved O2)

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17
Q

Is O2 binding Hb reversible or irreversible?

A

reversible

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18
Q

Is relationship of % saturation Hb and PO2 in arteries linear?

A

no - its nonlinear

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19
Q

What is P50?

A

PO2 at which Hb is 50% saturated

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20
Q

What is positive cooperativity?

A

change in affinity of heme groups for O2 as each successive O2 molecule binds = steep part of Hb-O2 dissociation curve

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21
Q

Where is Hb loading of O2?

A

into pulmonary capillaries from alveolar gas

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22
Q

Where is Hb unloading of O2?

A

from systemic capillaries into tissues

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23
Q

How saturated is Hb in systemic venous capillaries?

A

75% saturated

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24
Q

How saturated is Hb in alveolar arterial capillaries?

A

97.5% saturated = basically 100%

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25
What is PO2/PCO2 right before and right after alveoli?
``` before PO2 = 40 PCO2 = 45 after PO2 = 100 PCO2 = 40 ```
26
What is PO2/PCO2 right before and right after peripheral tissue?
``` before PO2 = 100 PCO2 = 40 after PO2 = 40 PCO2 = 45 ```
27
What 3 things cause shift to right in O2-Hb dissociation curve?
- increased temp - increased 2-3 DPG - increased H+ or PCO2
28
What does decreased affinity of Hb for O2 do to dissociation curve?
shift to the right
29
What does decreased affinity of Hb for O2 do to P50?
increase in P50
30
What does shift right in Hb curve mean for O2 unloading?
easier to unload O2
31
What is effect of acidic pH on Hb dissociation curve?
shift right, decreased affinity
32
What is effect of high CO2 on Hb dissociation curve?
shift right, decreased affinity via BOHR effect
33
What is effect of 2,3 DPG on Hb dissociation curve?
shift right | binds B chain and reduces affinity for O2
34
What 5 things cause shift to left on O2-Hb dissociation curve?
- decreased temp - decreased 2-3 DPG - decreased H+ - fetal HbF - CO
35
What does increased affinity of Hb for O2 do to Hb dissociation curve?
shift left
36
What does increased affinity of Hb for O2 do to P50?
decrease in P50
37
What does shift to left in Hb dissociation curve do to unloading of O2 in tissues?
decrease in unloading of O2 to tissues
38
What is HbF? What does it do to Hb dissociation curve?
- fetal hemoglobin, contains gamma chain instead of B chain - 2,3 DPG doesn't bind to gamma chain - has higher affinity for O2 - shift left dissociation curve
39
What is affinity of CO for Hb compared to O2?
CO has 250x higher affinity than O2
40
What forms in blood due to presence of CO?
carboxyhemoglobin
41
What is shape of curve of CO-Hb binding?
asymptotic [rather than sigmoid like the O2 one]
42
What are 3 forms CO2 transported in blood?
- free in solution [7% dissolved] - bound to proteins [3% bound to Hb] - chemically modified [90% to HCO3-]
43
What is solubility of CO2?
0.07 mL CO2/100 mL blood / mmHg
44
What is conc of CO2 following Henry's law?
conc = PCO2 * solubility = 40 mmHg * 0.07 = 2.8 mL CO2/100 mL blood
45
Does CO2 bind to same or different site than O2 on Hb?
CO2 binds to different site than O2
46
What is haldane effect?
- less O2 bound to Hb [less saturation ] --> higher Hb affinity for CO2 - get left shift on CO2 dissociation curve when you have less O2 bound
47
Path of CO2 transport in blood starting with tissue
at tissue site: - tissue produces CO2 from metabolism - CO2 diffuses across cell membranes into RBC - carbonic anhydrase in RBC catalyzes hydration of CO2 into H2CO3 - H2CO3 dissociates into H+ and HCO3 - H+ buffered by deoxyHb within RBC - HCO3 diffuses out to plasma and exchanged with Cl- in lung: - H+ released from buffering site on deoxyHb - HCO3 enters RBC in exchange for Cl- - H and HCO3 form H2CO3 - H2CO3 dissociates to CO2 and H2O - CO2 expired from lungs
48
What is normal blood pH?
7.38-7.42
49
What is normal arterial PCO2/PO2?
PCO2: 40 mmHg PO2: 100 mmHg
50
What is equation for minute ventilation [MV]?
MV = Vt [tidal vol] * RR [resp rate]
51
What are two equations for alveolar ventilation [V[A]]?
V[A] = (Vt [tidal vol] - Vd [dead space vol])*RR V[A] = VCO2 * K / PACO2
52
What is equation for Vd?
Vd = Vt * [PaCO2 [arterial] - PECO2 [expired]] / PaCO2
53
What is equation for alveolar PO2?
alveolar PO2 = PIO2 [inspired] - (PACO2 [alveolar] / R [respiratory exchange ratio])
54
What is equation for PIO2?
PIO2 = (Pb [barometric] - Ph2o) * FIO2 [fraction inspired O2]
55
What is definition of hypoxemia?
decrease in arterial PaO2
56
What is the A - a gradient?
alveolar PAO2 - arterial PaO2 = (PIO2 - PACO2/R) - PaCO2 a = arterial, A = alveolar, I = inspired
57
What is normal Aa gradient?
< 12 mmHg
58
What can causes normal Aa gradientt? big gradient?
normal: small amount of blood goes through physiologic shunt big: age [due to loss elastic recoil of lungs], alveolar disease [abnormal gas exchange], shunt [such as R-L]
59
Can you derive the Aa gradient from oximetry or %SaO2?
No
60
Can you derive the Aa gradient from ABG info?
yes
61
What is the respiratory exchange ratio?
rate of CO2 production compared to rate of O2 production
62
What is value of R in steady state?
0.8
63
What are 5 causes of hypoxemia?
- high altitude - hypoventilation - diffusion defect - V/Q defect - R-->L shunt
64
In high altitude what happens to PaO2, A-a gradient, effect of supplemental O2?
- decreased PaO2 - normal A-a gradient - supplemental O2 improves
65
In hypoventilation what happens to PaO2, A-a gradient, effect of supplemental O2?
- decreased PaO2 - normal A-a gradient - supplemental O2 improves
66
In diffusion defect what happens to PaO2, A-a gradient, effect of supplemental O2?
- decreased PaO2 - increased A-a gradient - supplemental O2 improves
67
In V/Q defect what happens to PaO2, A-a gradient, effect of supplemental O2?
- decreased PaO2 - increased A-a gradient - supplemental O2 improves
68
In R-->L shunt what happens to PaO2, A-a gradient, effect of supplemental O2?
- decreased PaO2 - increased A-a gradient - supplemental O2 does not help
69
What is mech of high altitude changing PaO2?
- low Pb [barometric] causes low PIO2 and thus PAO2 [alveolar[ - normal diffusion across capillaries to PaO2 is same as PAO2 [both low] - normal A-a gradient [since diffusion works] - supplemental helps by increasing inspired PIO2 and thus PAO2/PaO2
70
What is mech of hypoventilation changing PaO2?
- decreased alveolar PAO2 in hypoventilation - normal diffusion so normal A-a gradient - since low PAO2 get low PaO2 [arterial] - supplemental O2 helps by increasing PAO2 alveolar
71
What is mech of diffusion defects changing PaO2?
- pulm fibrosis or edema or other causes increased diffusion distance or decreased surface area - get increased A-a gradient - thus PaO2 [arterial ] < PAO2 - supplemental O2 helps by increasing alveolar PAO2 and increasing driving force for diffusion
72
What is mech of V/Q defects changing PaO2?
- have increased dead space - high V/Q --> pulm clot - low V/Q --> area of alveolar flooding with pus [pneumonia or obstruction] - get increased A-a gradient - have low PaO2 since not as much diffusion - supplemental O2 helps
73
What is mech of right to left shunt changing PaO2?
- blood is completely bypassing the alveoli - deox blood mixed with normal ox non-shunted blood and dilutes it - A-a gradient is increased - supplemental O2 does not help because shunted blood just keeps diluting the oxygenated blood
74
What is hypoxia?
- decreased O2 delivery to tissue
75
true or false: hypoxemia leads to hypoxia?
true: if you aren't getting any air in it certainly can't go to the tissues
76
What is eq. for O2 delivery?
O2 delivery = CO * O2 content of blood
77
What is biggest contributor to O2 content of blood?
Oxy-Hb
78
What 4 things can cause hypoxia [other than causes of hypoxemia]?
1. low CO: due to low blood flow 2. anemia 3. CO poisoning 4. CN poisoning
79
What are two mech that anemia does?
- lowers Hb conc | - low O2 content of blood
80
What are two mech that CO does?
- lowers O2 content of b lood | - shifts left the Oxy-Hb curve
81
What does CN poisoning do?
decreases O2 utilization by tissues

Physiology Part 2 (19 decks)

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