A gravitational pressure regulating valve to regulate fluid flow of a patient, including a fluid chamber having an inlet port to receive a bodily fluid and an outlet port to discharge received bodily fluid, the fluid chamber including a first chamber configured to capture a non-buoyant member therein and to guide the non-buoyant member along a longitudinal axis of the first chamber to facilitate bi-directional reciprocating movement of the non-buoyant member to and from the inlet port, and a second chamber configured to capture one or more buoyant members therein such that when the second chamber is filled with bodily fluid, at least one of the buoyant members applies a resolved buoyant pressure from a buoyant force of the one or more buoyant members in opposition to an inlet pressure of fluid at the inlet port.