Raylan was riding his horse across in the back woods of kentucky. his horse was startled by a harmless garter snake on the path and raylan was thrown off his horse. he hit his thoracic cage hard on a fallen limb. his ribs hurt but he thought he could make it home. as he continued his ride, breathing became more and more difficult. once home, he experienced sharp chest pains, with great difficulty breathing. he was rushed to the hospital and the doctors suspected a pneumothorax. what is a pneumothorax? why is the fluid bond between the parietal pleura and visceral pleura so important in ventilation? explain what pressures are involved.

Basically, pneumothorax is the presence of free air inside the pleural cavity. Under normal health conditions the parietal pleura and visceral pleura are connected by this space called pleural cavity, which is filled with a fluid called pleural fluid. This fluid is important for preventing friction between the lungs and ribcage and also to link the pleural tissues by a negative pressure (intrapleural pressure) about 5mmHg lower than the alveolar pressure. This pressure difference allows constant opening of the lungs, favoring a satisfactory ventilation.

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.