The respiratory tract and its infections

This is the time of year when respiratory tract infections act up, so we've created a brief guided tour to the common cold and four of its fellow misery makers. Please refer to the illustration as you read along. Flu is not included because the focus is on anatomical locations in the respiratory tract, and flu's effects are widespread. A couple of themes emerged as we put this article together. First, it's true: washing your hands may be your best defense against respiratory infection. Second, antibiotics are important arrows in the treatment quiver, but they've been overused, especially for sinusitis and bronchitis.

1. Common cold

What is it? Inflammation of the mucous membranes that line the nose.