Quick Answer. The function of the cartilaginous rings of the trachea is to stabilize the trachea and keep it rigid while allowing the trachea to expand and lengthen when the person breathes. If the trachea was not supported in this way, it would simply collapse because of the pressure of the chest.
1 The Pill. The pill is the common name for oral contraception. It's one of the safest, most effective, and popular methods of birth control. The pill is made up of synthetic forms of hormones that naturally occur in a female's body - progestin and estrogen.
Birth Control Shot. The birth control shot, known as Depo Provera, is a hormonal injection that protects against pregnancy for three months. For the typical couple, it is more effective than the birth control pill -- only 3% of users get pregnant in a year. Pros: Only injected four times per year, highly effective. Cons: Cost (about $240 per year), may cause spotting and other side effects.