Transport of O2 and CO2 and the Regulation of Ventilation

Question 1

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

Answer 1

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

Question 2

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?

Answer 2

Carrying capacity (HbO2 content vol%)

Question 3

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

Answer 3

• 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.

Question 4

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

Answer 4

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

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

Question 5

Effects of carbon monoxide on oxygen transport

Answer 5

• 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

Question 6

What is the haldane effect

Answer 6

Remove O2 from Hb facilitates formation of HCO3 in RBC

*because deoxygenated Hb is better buffer

Question 7

What is the function of the chloride shift at the RBC

Answer 7

Maintain neutrality of RBC when HCO3 moves to plasma

*change Cl by HCO3

Question 8

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

Answer 8

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)

Question 9

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

Answer 9

CO2

Question 10

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

Answer 10

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

*indirect stimulation

Question 11

Uses of the hyperbaric oxygen

Answer 11

• carbon monoxide poisoning
• compromised tissue graphs
• gas gangrene

Question 12

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

Answer 12

HCO3-

Question 13

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

Answer 13

Alkalosis

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

Question 14

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

Answer 14

H+

Question 15

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

Answer 15

More than 5 to 6 liters over 24 hours

Citrate (store blood contain as anticoagulant)