In our body there are many types of cells with different shapes and functions. Cells are organized into groups, which “working” in an integrated manner perform a particular function together. These cell groups are the tissues.
Human body tissues can be classified into four main groups: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
The cells of epithelial tissue are very close together and there are almost no substances filling space between them. This type of fabric has the main function to cover and protect the body. It forms the epidermis, the outermost layer of the skin, and internally coats organs such as the mouth and stomach.
Epithelial tissue also forms the glands - structures composed of one or more cells that make certain types of substances in our body such as hormones, digestive juices, tears and sweat.