Which of the following statements about pulmonary ventilation is false?

a. Normal expiration requires the use of the expiratory muscles to decrease lung volume.

b. The inspiratory muscles increase lung volume, which decreases intrapulmonary pressure.

c. For inspiration to occur, intrapulmonary pressure must decrease below atmospheric pressure.

d. The intrapleural pressure is less than the intrapulmonary pressure; this prevents the lungs from collapsing during expiration.

Video transcript

Hi, everyone. Let's take a look at this practice problem together. What happens to intrapulmonary and atmospheric pressures between breaths? The answer options are a intrapulmonary pressure is higher than atmospheric pressure. B, intrapulmonary pressure is lower than atmospheric pressure. C intrapulmonary and atmospheric pressures are equal and d intrapulmonary pressure fluctuates during this period. So what are intrapulmonary and atmospheric pressures recall that atmospheric pressure is the pressure of the air outside of our bodies? And intrapulmonary pressure is the pressure of the gasses within the alveoli. Now, how do these pressures play a role in respiration? Recall that air movement into and out of the lungs is due to pressure gradients where air moves from areas of high pressure to areas of low pressure. So that concept right there, that air moves from high pressure to low pressure is an important concept to re to remember. Now, keeping that in mind what happens to intrapulmonary and atmospheric pressures between breaths? Let's take a look at the answer options option. A if the intrapulmonary pressure is higher than the atmospheric pressure, air will flow from the alveoli where the pressure is high out of the lungs to the atmosphere where the pressure is lower. And this is called expiration option B, if the intrapulmonary pressure is lower than atmospheric pressure, air will flow from the atmosphere into the lungs and alveoli. And this is called inspiration. Now note that our question was what happens to pressures between breaths, well, between breaths, there is no air movement. So that means that both options A and B are incorrect. If there is no air movement, that means that the pressures are equal. Now, option D is incorrect because the intrapulmonary pressure is not fluctuating, it remains constant. The correct answer is option C inter pulmonary and atmospheric pressures are equal. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.