Questions: 1 Pulmonary ventilation is best defined as a. the movement of gases across the respiratory membrane. b. the exchange of gases between the blood in the systemic capillaries and the tissues. c. the physical movement of air into and out of the lungs. d. the movement of gases through the blood. 2 How are pressure and volume related, according to Boyle's law? 3 Air moves out of the lungs when a. intrapulmonary pressure is less than atmospheric pressure. b. intrapulmonary pressure is greater than atmospheric pressure. c. blood pressure is greater than intrapulmonary pressure. d. blood pressure is less than intrapulmonary pressure.

1. The answer is the third one (C): the physical movement of air into and out of the lungs.

   • A: the movement of gases across the respiratory membrane. This describes gas exchange, not ventilation.
   • B: the exchange of gases between the blood in the systemic capillaries and the tissues. This describes internal respiration, not ventilation.
   • C: the physical movement of air into and out of the lungs. This accurately defines pulmonary ventilation.
   • D: the movement of gases through the blood. This describes gas transport, not ventilation.

2. Boyle's Law states that pressure and volume are inversely related when temperature is held constant. This means that as the volume of a gas increases, the pressure decreases, and vice versa. Mathematically, this is represented as \(P_1V_1 = P_2V_2\), where \(P\) is pressure and \(V\) is volume.

3. The answer is the second one (B): intrapulmonary pressure is greater than atmospheric pressure.

   • A: intrapulmonary pressure is less than atmospheric pressure. This condition causes air to move _into_ the lungs (inhalation).
   • B: intrapulmonary pressure is greater than atmospheric pressure. When the pressure inside the lungs (intrapulmonary) exceeds the pressure outside the body (atmospheric), air flows out of the lungs (exhalation).
   • C: blood pressure is greater than intrapulmonary pressure. Blood pressure does not directly control air movement in or out of the lungs.
   • D: blood pressure is less than intrapulmonary pressure. Blood pressure does not directly control air movement in or out of the lungs.

Summary:

1. Pulmonary ventilation is the physical movement of air into and out of the lungs.
2. According to Boyle's Law, pressure and volume are inversely related.
3. Air moves out of the lungs when intrapulmonary pressure is greater than atmospheric pressure.