The respiratory system is divided into four components: the upper respiratory system, lower respiratory system, chest wall and diaphragm. Upper respiratory system: The upper respiratory system comprises all structures and passages involved in the conduction of air from outside the body to the larynx. This system includes the nose, mouth and structures within the hypopharynx.
There are two fundamentally different types of laser eye surgery: PRK and LASIK. Under these two categories, there are several different flavors or modifications of each type.For example, LASEK (with an E) is a newer type of PRK.here are two fundamentally different types of laser eye surgery: PRK and LASIK. Under these two categories, there are several different flavors or modifications of each type.
PRK Eye Surgery Procedure â What is Photorefractive Keratectomy. PRK laser eye surgery, or PhoÂ­toreÂ­fracÂ­tive KerÂ­aÂ­teÂ­cÂ­toÂ­my is part of a famÂ­iÂ­ly of proÂ­ceÂ­dures called âsurÂ­face ablaÂ­tionsâ because the laser is applied directÂ­ly on the surÂ­face of the cornea rather than under a flap, as with LASIK. The PRK surgery is done under topÂ­iÂ­cal anesÂ­theÂ­sia and takes about 5 minÂ­utes per eye.