The present invention relates to a membrane unit adapted for use in a housingof a pressure measuring unit preferably for measuring pressure in an extra-corporal blood circuit comprising a flexible membrane and a fixing ring whichis integral with the membrane so that the membrane and the fixing ring form aone-piece element, wherein the fixing ring has a lower flexibility than themembrane and wherein the fixing ring comprises fixing elements for fixing thefixing ring to the pressure meas~uring housing. The invention further relatesto a housing as well as to a pressure measuring unit.
