Explain the Synchronous Up-Down Counters?

The circuit of a 3-bit synchronous up-down counter and a table of its sequence are shown below.  Alike to an asynchronous up-down counter and a synchronous up-down counter also has an up-down control input and it is used to control the direction of the counter through a certain sequence.

• In favor of both the UP and DOWN sequences Q0 toggles on each clock pulse.
• In favor of the UP sequence Q1 changes state on the next clock pulse when Q0=1.
• In favor of the DOWN sequence Q1 changes state on the next clock pulse when Q0=0.
• In favor of the UP sequence Q2 changes state on the next clock pulse when Q0=Q1=1.
• In favor of the DOWN sequence Q2 changes state on the next clock pulse when Q0=Q1=0.