Every organ in the human body is composed of one or more tissues. The study of these tissues is known as histology. It is because of histology that the structure of organs can be researched and understood. Since organs are composed of tissues, it is important to understand each tissue type, their structure, their location, and their functions to better understand how each organ operates within the human body.
Tissues are composed of groups of cells that have similar shapes and functions. There are four main types of tissue found in the human body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Each tissue has unique characteristics that differentiate them from one another. Epithelial tissue covers the surface of the body, connective tissue adds support and structure to the body, muscular tissue contracts to allow movement, and nervous tissue controls the organs (Hoehn & Marieb, 2007, p. 118).
Epithelial tissue covers the surface of the human body and lines most internal cavities. Epithelial tissue is found in the body’s skin, lining of the stomach and intestines, the kidney, and glands, as well as other locations within the body (Amsel, 2012). The two types of epithelial tissue are (1) covering and lining epithelium and (2) glandular epithelium. The covering and lining epithelium are found lining the integumentary, digestive, cardiovascular, and respiratory systems as well as the ventral body cavity and the organs this cavity houses (Hoehn, et al., 2007, p. 118). The glandular epithelium is found within the glands of the entire human body. Not only are their two types of epithelial tissue found in the human body, there are also multiple classifications and various shapes. These classifications include simple epithelia and stratified epithelia. The epithelial cells also differ. There are squamous cells, flat-like cells that look; cuboidal cells, shaped like cubes; and columnar cells, shaped like columns.
Simple epithelia are composed of a single layer of cells which are mostly concerned with absorption, secretion, and filtration because they are generally thin layers which do not offer great levels of protection (Hoehn, et al., 2007, p. 120). These simple epithelia can be found in the shape of simple squamous, simple cuboidal, simple columnar and psuedostratified columnar. Simple squamous epithelium are distinguished by the flattened cells with a disc-shaped nucleus and can be found in the kidneys, lungs, lining of heart, blood and lymphatic vessels, and the ventral body cavity. Simple cuboidal epithelium are distinguished by the cube-like cell shape with large spherical nuclei shapes and can be found in the kidney, small glands and the surface of the ovaries. Simple columnar epithelium are distinguished by the column shaped cells that house oval shaped nuclei inside and can be found in the gallbladder, digestive system, glands, and uterus. The psuedostratified columnar epithelium can still be...