What heart valves are found between the upper and lower chambers of the right and left sides of the heart?
The heart valves between upper and lower chambers are called atrioventricular valves/AV valves.
In the human heart, atria are superior in position while ventricles are inferior: the so called upper and lower chambers respectively. This is because of our bipedal gait.
Like all mammals, there are four chambers in the human heart and the left chambers are completely partitioned from the right chambers.
The left atria remains connected to left ventricle, in between the two, a bicuspid valve or mitral valve is present (left AV valve). The right atria remains connected to the right ventricle, and in between a tricuspid valve is present (right AV valve).
AV valves allow blood to flow from atria to ventricles but not in the opposite direction.