The trachea, also known as the windpipe, is a long, U-shaped tube that connects the larynx (voice box) to the bronchi and is a key part of the respiratory system. Its main function is to transport air to and from the lungs when a person breathes. When a person inhales, air travels through the nose or mouth, down the trachea, and into the lungs. When the lungs expel the air, it travels back up the trachea and out through the mouth or nose. The trachea is lined with cells that produce mucus, which helps capture microorganisms such as viruses and harmful bacteria before they enter the lungs. The trachea is also lined with tiny hair-like structures called cilia, which help push mucus that contains debris or pathogens out of the trachea. The trachea is made of rings of cartilage, which provide support and keep the airway open. The trachea also helps regulate the temperature of the air coming in and out of the lungs. Problems with the trachea include narrowing, inflammation, and some inherited conditions. In some cases, a procedure called a tracheostomy may be needed to help a person breathe if they have swallowing problems or conditions that affect coughing or block their airways.