When diving doubles you will need to use your wing/BCD to compensation. Typically you can't control your buoyancy only with a drysuit with steel doubles and stage bottles so you will need to use your wing to offset buoyancy.
The structure of the throat is designed to prevent food from entering the lungs. Photo Credit matthewennisphotography/iStock/Getty Images. When food enters the lungs instead of the esophagus, it affects breathing and can cause choking and other problems.
During breathing the valves open to allow air to enter the nose, larynx, and trachea and close to prevent air from entering the esophagus and lower digestive tract. During swallowing the valves open to allow food to enter the digestive tract and prevent food from penetrating the nose and larynx and entering the airway. During swallowing the goal of the system is to move food into the digestive system and keep it out of the respiratory system.