Basement membranes are thin, flexible layers of extracellular matrix that provide structural support to various tissues in the body. They are primarily composed of proteins like collagen, laminin, and fibronectin, which help anchor cells and maintain tissue integrity. These membranes are found beneath epithelial cells, surrounding muscle cells, and in the nervous system. In addition to providing support, basement membranes play a crucial role in filtration and cell signaling. They act as a barrier, regulating the movement of substances between tissues. This is particularly important in organs like the kidneys, where basement membranes help filter blood and maintain proper function.