Trachea lining. Coloured scanning electron micrograph (SEM) of a section through the wall of a trachea (wind pipe). The trachea links the larynx to the lungs. The lining consists of mucus-secreting goblet cells (one seen at centre, pink) and epithelial cells (vertical) that are covered in cilia (hair-like). Mucus traps debris, such as dust particles or bacteria, in the inhaled air, while the beating of the cilia moves the mucus and particles upwards out of the respiratory tract. This helps to k
