Transport of O2 and CO2 and the Regulation of Ventilation Flashcards

1
Q

Factors that shift to the right the O2-Hb dissociation curve

A
  • ⬆️ CO2 (Bohr effect)
  • ⬆️ H (⬇️ pH)
  • ⬆️ Temperature
  • ⬆️ 2,3-BPG
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2
Q

What happen when the shift of the O2-Hb dissociation curve doesn’t change the affinity of Hb to O2 (P50 remains normal) and at PO2=100 mm Hg saturation is still close to 100%? What is the the most probably change?

A

Carrying capacity (HbO2 content vol%)

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3
Q

What is the effect of shift (right or left) the O2-Hb dissociation curve on the transport of oxygen?

A
  • shift left: ⬇️ P50 ▶️ ⬆️ affinity Hb to O2 ▶️ load O2
  • shift right: ⬆️ P50 ▶️ ⬇️ affinity Hb to O2 ▶️ unload O2

*at PO2=100 mmHg there is close 20% vol HbO2 content, it wouldn’t affect saturation nor carrying capacity, just affinity.

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4
Q

In what cases is the carrying capacity of the blood for O2 changed?

A
  • Anemia: ⬇️ [Hb] ▶️ ⬇️ carrying capacity (⬇️ O2 content)
  • Polycythemia: ⬆️ than normal [Hb] ▶️ ⬆️ carrying capacity (⬆️ O2 content)

*P50 (affinity), saturation (O2 per g Hb) doesn’t changed

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5
Q

Effects of carbon monoxide on oxygen transport

A
  • shift left Hb-O2 dissociation curve (⬆️ affinity Hb for O2)
  • ⬇️ P50
  • ⬇️ % saturation (O2 per g Hb)
  • ⬇️ O2 content (vol%)

*affects both; carrying capacity and affinity

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6
Q

What is the haldane effect

A

Remove O2 from Hb facilitates formation of HCO3 in RBC

*because deoxygenated Hb is better buffer

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7
Q

What is the function of the chloride shift at the RBC

A

Maintain neutrality of RBC when HCO3 moves to plasma

*change Cl by HCO3

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8
Q

What happen with ventilation in case of acute rise of arterial H+ (⬇️ pH)?

A

No change in ventilation - BBB is not permeable to H+

*there isn’t stimulation of central chemoreceptors. They sense H+ in CSF through CO2 (cross BBB)

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9
Q

Main or total drive for ventilation under resting conditions at sea level is accomplished by

A

CO2

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10
Q

How does the anemia stimulate ventilation if there’s normal PO2 and saturation%?

A

⬇️ HbO2 content ▶️ ⬇️ O2 delivery ▶️ ⬆️ lactic acid (H+) ▶️ stimulate chemoreceptors

*indirect stimulation

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11
Q

Uses of the hyperbaric oxygen

A
  • carbon monoxide poisoning
  • compromised tissue graphs
  • gas gangrene
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12
Q

The largest quantity of carbon dioxide in venous blood is transported as

A

HCO3-

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13
Q

Which factor would tend to reduce the increase in ventilation at high altitude?

A

Alkalosis

*At high altitude, hypoxia stimulates ventilation through the arterial chemoreceptors. This decreases arterial PCO2 (hypocapnia) and causes alkalosis. Alkalosis inhibits ventilation.

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14
Q

Central chemoreceptors of the medulla respond most directly to which substance in the cerebrospinal fluids and extracellular fluid?

A

H+

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15
Q

What quantity of transfused blood is required to cause hypocalcemia and why does it happen?

A

More than 5 to 6 liters over 24 hours

Citrate (store blood contain as anticoagulant)

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