A pressure actuated valve for controlling the flow of fluid through a medical device, the valve comprises a housing including a lumen extending therethrough and a flow control membrane extending across the lumen to control the flow of fluid through the lumen. The membrane includes a plurality of slits extending therethrough so that, when the membrane is acted upon by a pressure of at least a threshold magnitude, the slits open to permit flow through the lumen and, when not acted upon by a pressure of at least the predetermined magnitude, the slits are maintained closed by a biasing force applied thereto by the membrane to prevent flow through the lumen. Each of the slits extends between end portions thereof along a curve wherein a distance between a first end portion of a first one of the slits and a first end portion of a second one of the slits is a minimum distance between the first and second slits.