The trachea, also called the windpipe, is a tube that carries air from the mouth and nose to the lungs. The trachea is about four inches long and consists of cartilage, muscles, and membranes.

The cartilage forms a flexible skeleton that keeps the trachea open so air can pass through. The muscles contract and relax to help move air through the trachea.

The membranes line the inside of the trachea and secrete mucus, which traps dust and other particles so they do not enter the lungs.

The trachea divides into the left and right bronchi at the level of the fifth thoracic vertebra. The bronchi are tubes that carry air to the left and right lungs, respectively.

The bronchi divide into smaller tubes called bronchioles, which end in tiny air sacs called alveoli. The alveoli are where gas exchange occurs between the air and the blood. Oxygen from the air diffuses into the blood, and carbon dioxide diffuses from the blood into the air.

The trachea is a vital part of the respiratory system and without it, the gas exchange would not be possible. The trachea is constantly exposed to potential harm from inhaled irritants, such as smoke and bacteria.

To protect the trachea, there are several mechanisms in place. The mucus that is produced by the membranes traps particles and prevents them from entering the lungs. The cilia, tiny hairlike structures, beat rhythmically to move the mucus and trapped particles up and out of the trachea.

The epiglottis, a flap of tissue that covers the trachea when we swallow, prevents food and liquids from entering the lungs.

Despite these mechanisms, the trachea can still become damaged. Infections, such as influenza and pneumonia, can cause inflammation and swelling of the trachea.

In severe cases, the trachea can become blocked, making it difficult to breathe. Chronic inflammation from smoking can also damage the trachea and lead to difficulties breathing.