ANATOMY&PHYSIOLOGY FOR NURSES

Columnar Epithelium    forms a single layer of cells which line the ducts of most glands, the gall bladder, nerly the whole of the digestive tract, in which goblet cells are interspersed,and parts of the genito- urinary tract. The illustration columnar cells from the interstine; these have a slightly striated border. In some situations, as when lining the alveoli of secreting glands, the cells of columnar epithelium are short and have a cubical appearance they are then described as cubical cells. Ciliated Epithelium, is found lining the air-passages and their ramifications such as the frontal and maxillary sinuses. It also lines the uterine tubes or oviducts and part of the uterus and the ventricles of the brain. Ciliated cells are like columnar cells in shape,but they have in addition fine hair like processes attached to their free edge.  These processes are called cilia.  The ciliary processes keep up a continual movement directed towards the external opening.  This movement has been likened to the movement seen in a field of corn, blown in one direction by the wind. In the respiratory passages the constant movement prevents dust, mucus, etc., entering the lungs, and in the uterine tubes the movement conveys the ovum into the uterus. Goblet Cells are mucus - secreting cells which lie in the walls of glands and ducts lined by columnar cells, either plain or ciliated. Goblet cells secrete mucus or mucin and express it on to the surface; they act as mucus-secreting glands and are most numerous where a considerable amount of mucus covers the surface as in the stomach, colon, and trachea.