Trachea annular ligaments of trachea. The epiglottis closes the opening to the larynx during swallowing. The trachea develops in the second month of development. It is lined with an epithelium that has goblet cells which produce protective mucins (see "Respiratory epithelium"). An inflammatory condition, also involving the larynx and bronchi, called croup can result in a barking cough. A tracheotomy is often performed for ventilation in surgical operations where needed. Intubation is also carried out for the same reason by the inserting of a tube into the trachea. From 2008, operations have experimentally transplanted a windpipe grown by stem cells, and
Human-body model Human-body model The human-body model (HBM) is the most commonly used model for characterizing the susceptibility of an electronic device to damage from electrostatic discharge (ESD). The model is a simulation of the discharge which might occur when a human touches an electronic device. The HBM definition most widely used is the test model defined in the United States military standard, MIL-STD-883, Method 3015.9, Electrostatic Discharge Sensitivity Classification. This method establishes a simplified equivalent electrical circuit and the necessary test procedures required to model an HBM ESD event. An internationally widely used standard is JEDEC standard JS-001. HBM is used