RT Cardiopulmonary A&P Ch. 9

What is the average amount of CO2 produced by the body at rest?

200 mL/min

What is the average tissue-blood CO2 gradient?

6 mm Hg

What is the approximate percentage of dissolved CO2?

8%

What is the approximate percentage of CO2 transported as HCO3-?

80%

The majority of CO2 is transported in which of the following forms?

Plasma HCO3-

During cardiac resuscitation a 63-year-old man receives sodium bicarbonate for a profound metabolic acidosis. Why should the respiratory therapist increase ventilation at this point?

To eliminate the additional CO2 generated by lactic acid buffering.

Which of the following mechanisms is responsible for maintaining a normal PaCO2 near 40 mm Hg during heavy exercise?

VA normally increases such that it eliminates CO2 at a rate proportional to its production.

Which of the following is the best explanation for the chloride shift?

HCO3- diffuses out of the RBC and leaves the cell electropositive.

The affinity of hemoglobin for CO2 is greater when it is not combined with oxygen. What is the name of this phenomenon?

Haldane effect

Which of the following statements are true of CO2? I. Most CO2 diffusing into the blood from tissue cells enters the erythrocyte. II. The rate of reaction between CO2 and H2O in the RBC is quite slow. III. The amount of CO2 carried as H2CO3 in the RBC is quite small. IV. The rate of reaction between CO2 and H2O in the RBC is quite fast.

I, II, and III

Which of the following statements are true of dissolved CO2? I. The rate of reaction between CO2 and H2O in the plasma is quite slow. II. The amount of CO2 carried as H2CO3 in the plasma is quite small. III. The amount of H2CO3 in the plasma is a major determinant of the blood's H+ concentration (pH). IV. The amount of H2CO3 in the plasma is not an important determinant of the blood's H+ concentration (pH).

I, II, and III

Which of the following statements explain the alkalemia that develops at high altitudes? I. Lack of oxygen at high altitudes creates a chemical stimulus for ventilation. II. Increased ventilation drives the PACO2 and PaCO2 below 40 mm Hg. III. Low PaCO2 lowers the blood H2CO3 concentration. IV. Low PaCO2 lowers PaO2 and promotes buffer release.

I, II, and III

What is the significance of the straight CO2 equilibrium curve versus the sigmoid-shaped HbO2 curve?

A change in alveolar ventilation is much more effective in changing arterial CO2 content than O2 content.

Which of the following are major forms of carbon dioxide transport? I. Internal metabolism II. Dissolved CO2 in plasma III. Plasma HCO3- IV. Protein carbamino compounds

II, III, IV

Although CO2 is technically not an acid, what is the reason for CO2 being conceptualized as though it were an acid?

Its immediate formation of H2CO3- in physiological fluids