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.
How effective is it? DMPA is one of the most effective methods of hormonal birth control available. When injections are received every 12-13 weeks, with perfect use, the effectiveness rate is over 99%. With typical use, effectiveness is three pregnancies per 100 women.