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.
Laser Eye Surgery. Excimer laser techniques to correct myopia and astigmatism. Unlike LASEK or LASIK technique for correction of refractive errors, PTK treatments will vary with different corneal disorders and the clinical goals of the procedure may likewise vary depending upon the patient's symptoms.