Histology and Epithelial Tissues Quiz

Overview of Histology and Epithelial Tissues

• Histology is the study of tissues and there are four main types: epithelial, muscle, nerve, and connective/supportive tissues.
• Epithelial tissues cover all external and internal surfaces of the body, and are responsible for contact with the environment through their function of secretion, absorption and response to stimuli.
• Body cavities not communicating with the internal or external surfaces of the body are lined by mesothelium, while the heart and vessels are lined by endothelium.
• Epithelial cells are held together in intimate contact with each other as well as to the underlying connective tissue, and are generally avascular.
• The basal lamina is a sheet-like extracellular structure composed of different components, and is attached to the underlying connective tissue by anchoring fibrils.
• Basal lamina have various functions, including structural, filtering, influence on cell polarity, regulation of cell proliferation and differentiation, and pathway for cell migration.
• The basement membrane is a layer visible beneath the epithelia in some organs, usually formed by fusion of two basal laminae or a basal lamina and a reticular lamina.
• Apical surface specializations include microvilli, cilia, and the glycocalyx, which represent the interface between epithelial cells and their external environment.
• Lateral surface specializations include tight junctions, zonula adherens, gap junctions, and desmosomes, which provide different types of adhesion and communication between cells.
• Basal surface specializations include hemidesmosomes, which are present in the contact zone between certain epithelial cells and basal laminae.
• Epithelia can be classified as covering and lining epithelia, which are sub-classified according to the number of layers into simple and stratified epithelia.
• Simple epithelia include simple squamous, cuboidal, and columnar epithelia, each with their own specific locations and functions in the body.