What do epithelia cover?,

The surface of the body (the epithelium of the skin is called epidermis) and its natural internal cavities (---open cavities that extend the inside of the body with the outside (airways, digestive tract,, urinary tract, genital tract) covered by mucosal epithelium ---closed cavities (cardiovascular cavities (vessels are covered by endothelium) and serous cavities (pleural (lungs), peritoneal (abdomen) and pericardial (heart) are covered by mesothelium)