Final answer:
Intrapulmonary pressure (Ppul) equalizes with atmospheric pressure (Patm) during breathing, so when Ppul is at equilibrium with Patm, the intrapleural pressure (Pip) should also be approximately 760 mm Hg.
Step-by-step explanation:
Intrapulmonary pressure (Ppul), also known as intra-alveolar pressure, is the pressure of the air within the alveoli in the lungs. It equalizes with the atmospheric pressure (Patm) during breathing. Atmospheric pressure at sea level is 760 mm Hg, and intrapulmonary pressure equalizes with this value. Therefore, the intrapleural pressure (Pip) when the Ppul is at equilibrium with atmospheric pressure should also be approximately 760 mm Hg.