NBRC Cardiopulmonary Anatomy and Physiology 3

Question 1

Which equation is used to estimate alveolar oxygen partial pressure (PAO2)?

Accepted Answer

Alveolar gas equation

Answer

The alveolar gas equation (PAO2 = FiO2 × [Pb – PH2O] – PaCO2/R) estimates the partial pressure of oxygen in the alveoli.

Question 2

Oxygen is primarily transported in the blood by:

Accepted Answer

Bound to hemoglobin

Answer

Approximately 97–98% of oxygen is transported bound to hemoglobin as oxyhemoglobin; only a small fraction dissolves in plasma.

Question 3

An increase in 2,3-DPG causes which shift of the oxyhemoglobin dissociation curve?

Accepted Answer

Right shift, decreasing oxygen affinity

Answer

Elevated 2,3-DPG reduces hemoglobin's affinity for oxygen, shifting the curve rightward and facilitating oxygen release to tissues.

Question 4

The normal mixed venous oxygen saturation (SvO2) is approximately:

Accepted Answer

60–75%

Answer

Normal SvO2 is 60–75%, reflecting the balance between oxygen delivery and consumption in systemic tissues.

Question 5

Which chemoreceptors respond most rapidly to changes in PaCO2?

Accepted Answer

Central chemoreceptors in the medulla

Answer

Central chemoreceptors in the medulla oblongata are highly sensitive to changes in cerebrospinal fluid pH caused by CO2 diffusion, driving the primary ventilatory response.

NBRC - National Board for Respiratory Care Practice Test

NBRC - National Board for Respiratory Care Practice Test

NBRC Cardiopulmonary Anatomy and Physiology 3