Endothelium is a layer of epithelium that lines the heart, blood vessels, lymph vessels, and the serous cavities of the body. The endothelium maintains an adequate homeostasis via its capacity to produce protective molecules. When this function is lost or damaged, endothelial dysfunction occurs, leading to a reduction in the capacity to maintain homeostasis and the development of pathological inflammatory processes and vascular disease. Description adpated from: https://www.ncbi.nlm.nih.gov/mesh/68004727 & https://pubmed.ncbi.nlm.nih.gov/16504104.