Trachea the trachea. The trachea is no more than 4mm diameter during the first year of life, expanding to its adult diameter by late childhood. The trachea is more mobile and of more variable length, deeper, and smaller in children. The trachea is lined with a layer of pseudostratified ciliated columnar epithelium. The epithelium contains goblet cells, which are glandular, modified simple columnar epithelial cells that produce mucins, the main component of mucus. Mucus helps to moisten and protect the airways. Mucus lines the ciliated cells of the trachea to trap inhaled foreign particles that the cilia then waft upward toward
Human body temperature Human body temperature Normal human body temperature, also known as normothermia or euthermia, is the typical temperature range found in humans. The normal human body temperature range is typically stated as . Individual body temperature depends upon the age, exertion, infection, sex, and reproductive status of the subject, the time of day, the place in the body at which the measurement is made, and the subject's state of consciousness (waking, sleeping or sedated), activity level, and emotional state. It is typically maintained within this range by thermoregulation. Taking a person's temperature is an initial part of a full clinical examination.