Diagram of a plica circulares. This is a diagram which shows the villi of the small intestine, as indicated by the arrows in the diagram above, at higher magnification. The main functions of the small intestine are digestion, absorption of food and production of gastrointestinal hormones.
Navy Divers perform underwater salvage, repair and maintenance, submarine rescue and support Special Warfare and Explosive Ordnance Disposal while using a variety of diving equipment. They also maintain and repair diving systems. Navy Diver class A school is 15 weeks in duration, and it is located in Panama City, Florida. Before attending the class A school, a seven week preparatory school will be completed at Naval Training Center, Great Lakes, Illinois. The Navy Diver rating requires a minimum of a six year enlistment obligation. Navy Diver (NOS E100) Enlistees are taught the fundamentals of diving through formal Navy schooling and on the job training.
This system was invented in 1943 and is what is in use today. It was also referred to back then as an aqualung. This invention really brought about the popularity of diving and allowed just about anyone to become a diver. Getting ready to go for a boat dive. To become a certified diver today, you need to take and pass a scuba diving certification class. There are national agencies that administer the class worldwide. The class begins with some book work and tests so you are familiar with the procedures and safety rules of diving.