Transport of O2 and CO2

Question 1

An increase in PaO2 causes an increase in dissolved O2. What is the normal dissolved O2 level at PaO2 of 100 mmHg?

Answer 1

1. 0.3 ml O2/100ml

Question 2

What is the dissolved O2 level during maximal hyperventilation at PaO2 of 130 mmHg?

Answer 2

1. 0.4 ml O2/100 ml

Question 3

Amount of O2 that a Gram of Hb can carry?

Answer 3

1.34 ml of O2

Question 4

Factors that ⬇️affinity or shift Oxygen-Hb curve to the right ?

Answer 4

1. ⬆️ CO2
2. ⬆️ H+ (⬇️PH) (acidity)
3. ⬆️ Temperature
4. ⬆️ 2,3 - BPG

Question 5

Factors that ⬆️ O2 affinity or shift Oxygen-Hb curve to the left?

Answer 5

1. ⬇️CO2
2. ⬇️H+ (⬆️PH or alkalinity)
3. ⬇️Temperature
4. ⬇️ 2,3- BPG

Question 6

What is P50?

Answer 6

1. The PO2 necessary to maintain SO of 50%

Question 7

What happens to P50 when you shift the curve to the right?

Answer 7

P50 ⬆️ (needs higher PO2 to maintain P50)

Question 8

What happens to P50 when curve shifts to the left?

Answer 8

2. P50 is ⬇️. (Need lower PO2 to maintain P50)

Question 9

Normal HbO2 content per volume of blood?

Answer 9

15g Hb x 1.34 ml of O2= 20 % volume or 20ml O2/100ml of blood at 100% SO2

Question 10

What happens to the total O2 content with anemia?

Answer 10

1. ⬇️

Question 11

What happens to the total O2 content with polycythemia ?

Answer 11

1. ⬆️

Question 12

What happens to the total O2 content with CO poisoning?

Answer 12

1. ⬇️

Question 13

What happens to the Hb SAT of O2 with CO poisoning?

Answer 13

1. ⬇️

Question 14

Forms of transport for CO2?

Answer 14

1. Bicarbonate (70%)
2. Carbaminohemoglobin (HbCO2) (25%)
3. Dissolved CO2 (5%)

Question 15

Where is the carbonic anhydrase found?

Answer 15

RBC

Question 16

Conversion of CO2 to HCO3?

Answer 16

CO2 + H2O H2CO3 H+
Carbonic Anhydrase

and HCO3-

Question 17

In general, what is the Haldane affect?

Answer 17

Oxygenated HB facilitates the elimination of CO2

Question 18

What are the 2 types of Chemorecptors?

Answer 18

1. Central chemoreceptors

2. Peripheral chemoreceptors

Question 19

Where are central chemoreceptors found?

Answer 19

1. Medulla

Question 20

What do central Chemoreceptors respond to?

Answer 20

1. CO2

Question 21

Why do central chemoreceptors respond better to CO2?

Answer 21

1. CO2 crosses BBB

Question 22

Difference between central and peripheral chemoreceptors in terms of adaptation?

Answer 22

1. Central = adapt

2. Peripheral = don’t adapt

Question 23

Where are the peripheral chemoreceptors located ?

Answer 23

1. Carotid bodies

2. Aortic bodies

Question 24

What are the different kinds of peripheral chemoreceptors?

Answer 24

1. H+/CO2 receptor

2. PO2 receptors

Question 25

What chemoreceptors are more sensitive?

Central Chemoreceptors
Peripheral H+/CO2 chemoreceptors

Answer 25

2. Central Chemoreceptors

Question 26

Mechanism of peripheral PO2 receptors ?

Answer 26

1. Only ⬇️ in PO2 causes activation of receptors.

2. Sensitivity is ⬆️⬆️ with ⬆️ in CO2.

Question 27

Why does anemia cause an activation of chemoreceptors if PaO2 is normal?

Answer 27

1. ⬇️O2 content —>
2. ⬆️Lactic Acid —>
   ⬆️H+

Question 28

At high altitudes, hyperventilation is a result of what chemoreceptor response?

Answer 28

1. Peripheral PO2 chemoreceptors

⬇️O2atm—> ⬇️PO2 —> ⬆️Ventilation

Question 29

Why does hypoxia cause a shift of the Oxygen-Hb curve to the right?

Answer 29

1. ⬆️EPO —> ⬆️RBC —>⬆️2,3- BPG

Question 30

Uses of hyperbaric O2?

Answer 30

1. CO poisoning
2. Gangrene (C. difficile and Staphylococcus aureus)
3. Decompression sickness