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CP2.10_O2 and CO2 Transport > O2 and CO2 Transport > Flashcards

O2 and CO2 Transport Flashcards

1
Q

Diffusion of gas into a tissue is directly proportional to (3):

A

ADP

  • surface area (A)
  • Diffusion coefficient (D)
  • Partial pressure difference (P1-P2)
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2
Q

Diffusion of gas into a tissue is inversely proportional (1):

A

to the thickness of the diffusion barrier (T).

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3
Q

RBCs spend about ___ seconds in pulmonary capillaries next to alveoli.

A

0.75 seconds

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4
Q

At rest, RBCs/Hb become fully saturated about after about how much time in the pulmonary capillary next to the alveolous?

A
  • 0.25 seconds.
  • 1/3rd way through pulmonary capillary.
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5
Q

During times of increased CO, RBCs/Hb become fully saturated about after about how much time in the pulmonary capillary next to the alveolous?

A
  • 0.25 seconds.
  • 1/2 way through pulmonary capillary.
  • RATE OF BLOOD FLOW FASTER.
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6
Q

Cause of hypoxia on exertion:

A
  • increased CO = increased rate of blood flow.
  • if barrier of diffusion is thickened (fibrosis), there is not enough time for RBCs to reoxygenate when passing through pulmonary capillaries.
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7
Q

Fick’s Law governs the diffusion of gas at the level of the alveoli. What is the equation (to determine what increases and decreases diffusivity)?

A

V = AD(P1-P2)/T

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8
Q

Perfusion limited:

A
  • Equilibrium (PA-Pa equalize) is reached within the amount of time the blood is in the pulmonary capillary.
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9
Q

Diffusion limited:

A
  • Equilibrium (PA-Pa equalize) DOES NOT OCCUR within the time the blood is in the pulmonary capillary.
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10
Q

Hemoglobin general structure:

A
  • heme component (iron): binds O2.
  • Two alpha chains, two beta chains.
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11
Q

Each gram of hemoglobin is capable of combining with about 1.39mL of oxygen under optimal conditions, but only 1.34 mL in blood. Why?

A
  • Hemoglobin in blood exists in different forms; such as methemoglobin.
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12
Q

At a PO2 of 100mm Hg (arterial blood), hemoglobin is what percent saturated?

A
  • about 97.4% (not 100% due to methemoglobin, etc.)
  • All 4 heme groups bound to O2.
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13
Q

At a PO2 of 40mm Hg (venous blood), hemoglobin is what percent saturated?

A
  • 75%
  • 3/4 heme groups bound to O2.
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14
Q

What does a shift in the Hb binding curve to the right indicate?

A
  • decreased Hb affinity for O2
  • more O2 unloading
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15
Q

What shifts the Hb binding curve to the right (decreased Hb affinity for O2/more unloading)?

A
  • increased PCO2 (decreased pH)
  • increased 2,3-BPG
  • increased temperature
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16
Q

What does a shift in the Hb binding curve to the left indicate?

A
  • increased Hb affinity for O2
  • less O2 unloading
17
Q

What shifts the Hb binding curve to the left (increased Hb affinity for O2/less unloading)?

A
  • decreased PCO2 (increased pH)
  • decreased 2,3-BPG
  • decreased temperature
18
Q

PCO2, pH, and temperature levels in metabolically active tissues:

A
  • higher PCO2
  • lower pH
  • higher temperature

FACILITATES O2 UNLOADING FROM Hb

19
Q

Anemia effect on oxygen in blood:

A
  • lack of RBCs.
  • Less RBCs = less Hb.
  • CaO2 decreases.
20
Q

Carbon monoxide effect on oxygen in blood:

A
  • less O2 bound to Hb.
  • decreased SaO2 and CaO2.
21
Q

CO2 is produced in the tissues and then carried to the lungs in the venous blood in three forms:

A
  • dissolved CO2 (5-10%)
  • carbaminohemoglobin (5-10%; CO2 bound to Hb)
  • HCO3- (90%)
22
Q

Steps in the process of CO2 transport as HCO3- in blood (formation to expiration):

A
  1. CO2 produced in tissue; diffuses into RBC.
  2. CO2 + H2O → H2CO3 → H+ + HCO3- (CA catalyzed)
  3. HCO3- leaves RBCs for Cl- (chloride shift)
  4. H+ in RBCs binds to deoxyHb.
  5. In lungs, all above reactions occur in reverse.
23
Q

Steps in the process of HCO3- to CO2 at lungs:

A
  1. HCO3- enters RBCs in exchange for Cl-.
  2. HCO3- + H+ → H2CO3 → CO2 + H2O.
  3. CO2 expired.
24
Q

Haldane effect:

A
  • deoxygenated blood increases Hb ability to carry CO2.
    • CO2 loading in tissue.
  • oxygenated blood decreases Hb ability to carry CO2.
    • CO2 unloading in lungs.
25
Q

Bohr effect:

A
  • H+ formed by the dissociation of carbonic acid into H+ and bicarbonate binds to amino acid residues on the globin chains of Hb.
  • Hb conformation change; oxygen released into tissues.

increased H+ levels in the tissue (decreased pH) leads to increased oxygen unloading.

26
Q

What form of hemoglobin buffers hydrogen ions formed by the dissociation of carbonic acid?

A

deoxyhemoglobin

CP2.10_O2 and CO2 Transport (1 decks)

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