Abstract: A pressure responsive dispensing pump has a hollow housing having walls forming a chamber coupled via an inlet to a supply of dispensable material. An inlet valve controls the flow of the material through the inlet into the chamber. The housing also has an outlet through which material may be discharged from the chamber under the control of a self-sealing outlet valve. At least one wall of the housing is displaceable inwardly of the chamber to reduce the volume thereof and force material out of the chamber via the outlet. The displaceable wall is connected to a flexible hinge which also moves inwardly of the chamber in response to the inward movement of the displaceable wall and thereby assists in discharging the contents of the chamber.