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_Physiology Exam 4 > 4/1: Respiratory - Transport of O2 and CO2 IV > Flashcards

4/1: Respiratory - Transport of O2 and CO2 IV Flashcards

1
Q

What do we want to be achieved?

A

Diffusion equilibrium

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2
Q

What is the PaO2 and PvO2?

A

The amount dissolved in plasma and will regulate how much is bound to hemoglobin (main way to transport oxygen)

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3
Q

Describe the alveolar values of PAO2 and the PACO2

A

PAO2 = 100
PACO2 = 40

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4
Q

Describe the oxygen levels in the arterial side of systemic arteries

A

Higher in oxygen
Blood received from pulmonary capillaries

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5
Q

Describe the arterial values of PaO2 and the PaCO2

A

PaO2 = 95 (partial pressure of oxygen in arterial blood)
PaCO2= 40 (higher because CO2 is being picked up by blood as it goes
through systemic capillaries)

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6
Q

Describe the oxygen in the venous side of systemic veins

A

Lower in oxygen because we have dropped off oxygen to tissues in systemic capillaries

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7
Q

Describe the venous values of PVO2 and the PVCO2

A

PVO2 = 40
PVCO2 = 46

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8
Q

What is hemoglobin saturation?

A

Amount of oxygen bound to oxygen

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9
Q

What is the hemoglobin saturation in systemic arteries and veins?

A

Around 97% when in systemic arteries (SaO2)
Around 75% when in systemic veins (SvO2)

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10
Q

Describe the partial pressure gradient if the cells utilize more oxygen

A

If the cells utilize more oxygen than normal, the gradient increases which
increases flow of oxygen from the blood to the tissues

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11
Q

What is tissue PO2 a function of?

A

Increased blood flow and/or metabolism result in more O2 delivery to the tissues (same thing works for CO2)
1. Rate of O2 transport to the tissues in blood (Blood flow)
2. Rate at which tissues use O2 (metabolism)

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12
Q

How can oxygen travel in the blood?

A
  1. Dissolved in plasma
  2. Bound to hemoglobin
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13
Q

Describe how oxygen travels dissolved in plasma

A

only 2% of total oxygen content is dissolved in plasma (PaO2 = 100 mmHg)

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14
Q

Describe how oxygen travels bound to hemoglobin

A

98% of total oxygen content is bound to hemoglobin via reversible binding to
the red blood cell (does not contribute to partial pressure)
- If we did not have hemoglobin, cardiac output at rest would have to be 83.3
L/min to transport sufficient oxygen to tissues (normal is 5)

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15
Q

What does the amount of oxygen bound depend on?

A
  • Dissolved plasma PO2
  • Number of binding sites in TBC depends on the Hb available
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16
Q

What does a heme group contain?

A

Iron

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17
Q

What state is iron in when it binds to oxygen?

A

In the ferrous state

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18
Q

What can one hemoglobin molecule bind to?

A

4 oxygen molecules

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19
Q

What is concentration of oxygen in arterial blood (CaO2)?

A

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

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20
Q

What does a reduction in the amount of Hb in the blood significantly reduce?

A

the blood oxygen content (because it’s the main transport mechanism)

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21
Q

What is the oxygen hemoglobin dissociation curve?

A

amount of oxygen bound to hemoglobin (y axis) depends on the amount of oxygen dissolved in plasma (x axis)

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22
Q

What does a higher amount of dissolved oxygen to to the amount bound to hemoglobin?

A

Higher amount

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23
Q

Describe an oxygen hemoglobin dissociation curve

A
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24
Q

What is oxyhemoglobin?

A

Has oxygen associated with it

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25
Q

When is hemoglobin’s affinity for O2 the highest in oxyhemoglobin?

A

At high dissolved amount (PO2) hemoglobin’s affinity for O2 is highest (positive cooperativity)

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26
Q

What does oxyhemoglobin contain?

A

Contains Heme group with iron that binds
to oxygen molecules

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27
Q

What is deoxyhemoglobin?

A

Does not have oxygen associated with it

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28
Q

When is hemoglobin’s affinity for O2 the highest in deoxyhemoglobin?

A

At low dissolved amount (PO2) the more likely O2 will dissociate from hemoglobin
(and Hb won’t have oxygen on it)

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29
Q

What does 2,3-BPG have to do with deoxyhemoglobin?

A

binds to beta subunit and
decreases its O2 affinity. Makes Hb more likely unload oxygen to the tissues. Made during metabolism.

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30
Q

Describe the right shift of the bohr effect

A

Right shift (at any given dissolved amount of oxygen, there’s less Hb saturated with
oxygen)

31
Q

Describe the left shift of the bohr effect

A

Left shift (at any given dissolved amount of oxygen, there’s more Hb saturated with oxygen)

32
Q

What does a right shift of the bohr effect indicate?

A

decreases affinity between
hemoglobin and oxygen

33
Q

What does a left shift of the bohr effect indicate?

A

an increased affinity between
oxygen and hemoglobin

34
Q

What occurs in a right shift of the bohr effect with oxygen and dissociating hemoglobin?

A

oxygen is more likely to
dissociate from hemoglobin (drop off more O2 to tissues, sign of metabolism)

35
Q

What occurs in a left shift of the bohr effect with oxygen and dissociating hemoglobin?

A

In this instance, oxygen is less likely to dissociate from hemoglobin

36
Q

What is a sign that tissue is probably not actively working/metabolism?

A

Left shift bohr effect

37
Q

What is a right shift of the bohr effect caused by?

A

(all indicators of increased need for oxygen in tissues. Local control)
-increased PCO2
-increased H+ (decreased pH, 7.2)
-increased temperature
-increased 2,3-BPG

38
Q

What is a left shift of the bohr effect caused by?

A

-decreased PCO2
-decreased H+ (increased pH 7.6)
-decreased temperature
-decreased 2,3-BPG
-carbon monoxide bound to Hb
-when Hb is in ferric state

39
Q

What are variants of hemoglobin?

A

things that can change hemoglobin’s ability to bind to oxygen

40
Q

What is carbon monoxides affinity for hemoglobin?

A

has 250x grater affinity for hemoglobin than oxygen

41
Q

What kind of shift is CO bound to Hb?

A

Left shift because increases Hb’s affinity for O2

42
Q

What are clinical descriptions of carbon monoxide poisoning?

A

Cherry red skin coloring, flu-like symptoms, headache, and neurologic symptoms occur
- Common in smoke and exhaust inhalation

43
Q

What is treatment for carbon monoxide poisoning?

A

Pure oxygen, 5% CO2

44
Q

What is methemoglobin?

A

When heme group is in Fe3+ state (ferric)

45
Q

Describe methemoglobin binding to O2

A

Ferric does not bind to O2 as readily as Fe2+ (ferrous) and causes any heme groups
in the same Hb molecule with ferrous state to have higher affinity for bound O2
(cooperativity)

46
Q

What kind of shift does methemoglobin cause?

A

Left shift Hb which is less likely to drop off O2 to tissues
- net effect is reduced O2 delivery to the tissues

47
Q

When does methemoglobin occur?

A

Due to G6PDH deficiency or upon exposure to some local
anesthetics (prilocaine and benzocaine causes ferrous → ferric, reducing oxygen transportability)

48
Q

What chains does hemoglobin f (fetal) contain?

A

contains 2 alpha and 2 gamma chains. 1 year after birth is
converted to adult Hb

49
Q

What is maternal Hb at any given fetal PO2?

A

At any given fetal PO2 →maternal has lower Hb
saturation with oxygen than fetal

50
Q

What is hemoglobin F (fetal) relationship with oxygen?

A

Has higher affinity for oxygen then HbA (adult), because it does not contain the
beta chain that normally would bind to 2,3-BPG

51
Q

What subunits does hemoglobin S (sickle cell) contain?

A

Normal alpha subunits and abnormal beta subunits due to a single amino acid change

52
Q

What do red blood cells form when hemoglobin S is deoxygenetaed?

A

Sickle cells (sickle cell disease), obstructing small vessels which can result in reduced blood flow to tissues resulting in less oxygen delivery

53
Q

What does O2 have a lower affinity for?

A

HbS than HbA

54
Q

What is hypoxemia?

A

low dissolved oxygen (PaO2), making Hb saturation (SaO2 lower)

55
Q

What are hypoxemia causes that result from an intake issue?

A

Red

56
Q

What are hypoxemia causes that result from a diffusion issue?

A

Yellow

57
Q

What are ways CO2 is transported in the blood?

A
  1. Dissolved CO2
  2. Carbamino-hemoglobin (CO2Hgb)
  3. Bicarbonate (HCO3)
58
Q

What are PCO2 levels in arterial blood and venous blood?

A

PaCO2 is 40 mmHg in arterial blood, PvCO2 46 mmHg in venous blood

59
Q

How does CO2 form a bond with hemoglobin in Carbaminohemoglobin and carbamino compounds?

A

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

60
Q

What kind of reaction is a Carbaminohemoglobin and carbamino compounds?

A

Slow reaction

61
Q

Describe CO2 in Carbaminohemoglobin and carbamino compounds in systemic capillaries

A

CO2 can bind to terminal amine groups

62
Q

Describe CO2 in Carbaminohemoglobin and carbamino compounds in pulmonary capillaries

A

CO2 unbinds and goes into alveolar air

63
Q

How does CO2 transport with bicarbonate in red blood cells?

A

In red blood cells, carbonic anhydrase rapidly forms carbonic acid from H2O
and CO2, which in turn dissociated to H+ and bicarbonate

64
Q

What does an increase in CO2 cause with bicarbonate?

A

Increase in CO2 causes reaction to move to the right
and produce bicarbonate (moves into plasma in
exchange for chloride) and protons (buffered by
binding to Hb in RBC)

65
Q

What does H+ combine with hemoglobin for?

A

buffering and HCO3- moved into plasma in exchange for Cl- (via band 3 protein)

66
Q

What happens to CO2 in tissues in active metabolism?

A

Increased CO2 (lower O2) production

67
Q

Where is CO2 dissolved into in systemic capillaries?

A

CO2 is dissolved into the plasma and into the RBC (bound to Hb making carbamino compounds)

68
Q

What does a carbonic anhydrase reaction create?

A

bicarbonate that goes into plasma via band 3 protein in exchange for Cl (bicarbonate out and Cl in)

69
Q

What happens to CO2 in lower O2 concentrations in systemic capillaries?

A

At lower O2 concentrations, CO2 is more likely to combine with Hb and Hb buffers more H+

70
Q

What is the haldane effect in systemic capillaries?

A

deoxygenated hemoglobin
promotes increased binding of CO2 to hemoglobin

71
Q

What happens to CO2 during breathing in pulmonary capillaries?

A

During breathing, decreased CO2 because it’s needed to remove CO2 from blood and breathe it out

72
Q

What is the direction of bicarbonate and Cl in pulmonary capillaries?

A

Reverse direction of the systemic reaction. Bicarbonate goes in and Cl goes out

73
Q

What happens to CO2 in higher O2 concentrations in pulmonary capillaries?

A

At higher O2 concentrations, CO2 is less likely to combine with Hb and Hb buffers more H+

74
Q

What is the haldane effect in pulmonary capillaries?

A

oxygenated hemoglobin
promotes dissociation of CO2 from Hb

_Physiology Exam 4 (8 decks)

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