Jennifer was running an 8K cross-country race. This race was the last of her high school career. She was on pace to set a new record. She started climbing the last hill, knowing just over the hill was the finish line. As she came over the hill three deer suddenly plowed through the runners, Jennifer was hit. She was thrown into the air upon impact by one of the deer. Jennifer was sitting on the ground, dazed and slumped to one side. Emergency Medical Technicians (EMTS) and an athletic trainer surrounded Jennifer. Jennifer's breathing was labored. EMT's noted Jennifer's wet gasping sounds with grunts of pain. A cervical collar was quickly placed on Jennifer and she was strapped to a backboard and transported to the nearest hospital.

Upon arriving at the hospital Jennifer's vital signs were BP 100/80, Pulse 108 and Respirations 23 breaths per minute. The doctors ordered x-rays of the chest. While waiting for X-rays, the Dr. Smith could see Jennifer was in pain. As Dr. Smith examined Jennifer he noticed bruising was forming on the lateral chest wall, just below the inferior tip of her scapula. There was a 2 inch laceration the extended deeply into her skin. The EMT's placed an adhesive seal over the wound before transporting her to the hospital. As Dr. Smith removed the adhesive seal, there was a gurgling, sucking sound each time Jennifer inhaled, and a small amount of blood foamed at the edges of the wound. Dr. Smith probed the wound and Jennifer screamed.

When the adhesive seal was removed, why did Dr. Smith hear a sucking sound each time Jennifer inhaled? What can you conclude about the pressure gradient between the atmosphere and the pleural cavity?