The present invention relates to a membrane unit adapted for use in a housing of a pressure measuring unit preferably for measuring pressure in an extra-corporal blood circuit comprising a flexible membrane (20) and a fixing ring (30) which is integral with the membrane so that the membrane and the fixing ring form a one-piece element, wherein the fixing ring has a lower flexibility than the membrane and wherein the fixing ring comprises fixing elements (32) for fixing the fixing ring to the pressure measuring housing (10). The invention further relates to a housing (10) as well as to a pressure measuring unit (10).
