CO2 Transport in the Blood

Question 1

What are the 3 ways to transport CO2 in the blood? How much is transported with each method?

Answer 1

1. Dissolved in plasma: 7%
2. Bound to Hb: 23%
3. Bicarbonate: 70%

Question 2

What enzyme catalyzes the conversion of CO2 to bicarbonate?

Answer 2

Carbonic anhydrase

Question 3

What happens to H+ and HCO3- levels during exercise?

Answer 3

H+ increases and HCO3- drops to restore equilibrium

Question 4

What is the optimum blood pH for humans?

Answer 4

7.4

Question 5

How does the amount of CO2 dissolved in the plasma compare for oxygenated and deoxygenated blood?

Answer 5

The same

Question 6

How does the amount of CO2 bound to hemoglobin compare for oxygenated and deoxygenated blood?

Answer 6

More in deoxygenated blood

Question 7

How does the carrying capacity of CO2 compare for oxygenated and deoxygenated blood?

Answer 7

Higher carrying capacity in deoxygenated blood

Question 8

How is CO2 loaded on hemoglobin at the tissues?

Answer 8

Deoxygenation of hemoglobin at the tissues frees up binding spots, and CO2 is loaded as carbamino-hemoglobin

Question 9

How is CO2 released from hemoglobin in the lungs?

Answer 9

Oxygen loading causes Hb to let go of the CO2

Question 10

Where does the

CO2 + H2O H2CO3 H+ + HCO3- reaction occur?

Answer 10

Inside red blood cells

Question 11

What is the membrane protein that sends bicarbonate across the cell membrane of red blood cells?

Answer 11

BandIII (an antiporter)

Question 12

What is the mechanism of bicarbonate transport across the red blood cell membrane?

Answer 12

Chloride shift

Question 13

What is the chloride shift?

Answer 13

BandIII brings one chloride ion into the red blood cell and send one bicarbonate out

Question 14

What is a metabolon?

Answer 14

A group of enzymes inside a cell that work together to perform a function

Question 15

What is happening with the chloride shift at the tissues?

Answer 15

CO2 diffuses into the blood, where carbonic anhydrase converts it to bicarbonate, and BandIII sends the bicarbonate into the plasma and brings in one chloride

Question 16

What is happening with the chloride shift at the lungs?

Answer 16

BandIII sends one chloride out of the cell and brings in one bicarbonate, carbonic anhydrase converts it back to CO2, which diffuses into the alveoli and gets exhaled

Question 17

What are the curves on a pH-bicarbonate plot called?

Answer 17

Isopleths

Question 18

What does the pH-bicarbonate plot tell physiologists?

Answer 18

Allows them to visualize what will happen to pCO2, pH, and bicarbonate levels if one of them changes

Question 19

What is hyperventilation?

Answer 19

The loss of too much CO2 by increased ventilation that is greater than what is needed to remove metabolism produced CO2

Question 20

What happens to CO2, pH, bicarbonate levels, and proton levels during hyperventilation? Which way does the carbonic anhydrase reaction shift?

Answer 20

CO2 drops, pH increases, proton levels and bicarbonate levels drop. Reaction shifts to the left

Question 21

What happens to CO2, pH, bicarbonate levels, and proton levels during hypoventilation? Which way does the carbonic anhydrase reaction shift?

Answer 21

CO2 increases, pH drops, proton and bicarbonate levels increase

Question 22

What condition is caused by hyperventilation?

Answer 22

Respiratory alkalosis

Question 23

What condition is caused by hypoventilation?

Answer 23

Respiratory acidosis

Question 24

What is hypoventilation?

Answer 24

Too much CO2 is retained by alveolar ventilation that is insufficient to remove the CO2 produced by metabolism

Question 25

What is respiratory acidosis?

Answer 25

When ventilation can’t remove all the CO2 produced by metabolism, so the blood pH decreases

Question 26

What is respiratory alkalosis?

Answer 26

When there is more ventilation than what is needed to remove the CO2 produced by metabolism, causing the blood pH to increase

Question 27

What are metabolic acidosis and metabolic alkalosis?

Answer 27

The pH change is caused by changes in metabolism rather than ventilation

Question 28

What causes metabolic acidosis?

Answer 28

Lactic acid buildup and diarrhea

Question 29

What causes metabolic alkalosis?

Answer 29

Loss of protons from vomiting

Question 30

What do central chemoreceptors detect?

Answer 30

CO2 levels

Question 31

What do peripheral chemoreceptors detect?

Answer 31

O2 levels

Question 32

How does altitude affect blood pH and ventilation?

Answer 32

At risk of hyperventilation since the air has less oxygen, and the breathing rate increases to accommodate for that, so we are losing more CO2 than we have so blood pH increases until the kidneys produce more red blood cells to carry O2