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.
Cataract surgery involves removing the natural lens of the eye and replacing it with an artificial lens (intraocular lens implant or IOL). The plastic artificial lens is permanent, requires no care, and can significantly improve vision.ataract surgery is a procedure used to remove the natural lens in the eye when it becomes clouded, and replace it with an artificial lens in order to restore clear vision.