Final answer:
Opening the valve would likely cause a lung collapse due to pneumothorax, as it disrupts the negative pressure necessary to keep the lungs inflated by allowing air into the intrapleural space
Step-by-step explanation:
The effect of opening the valve on the left lung would most likely cause lung collapse due to pneumothorax. This occurs because the intrapleural space is exposed to atmospheric pressure, disrupting the negative pressure that is necessary to keep the lungs inflated. When the valve is opened, air rushes into the intrapleural space, equalizing the pressure between the intrapleural space and the atmosphere, leading to the collapse of the lung. It is the disruption of the intrapleural pressure that directly causes the pneumothorax.
A pneumothorax affects lung compliance by making it more difficult for the lungs to expand, as the presence of air in the pleural space creates resistance to lung inflation. Therefore, compliance is actually decreased. Concerning intrapleural pressure, during normal breathing, this pressure is negative relative to atmospheric pressure, which is essential in allowing the lungs to inflate. However, when the pneumothorax occurs, this pressure becomes less negative or even positive, relative to atmospheric pressure, making it difficult or impossible to inhale normally.