Hi
Yes, you can use those uplink ports as regular network ports.
Note: out of box, 2 out of 4 (last 2 uplink port) are configured as VC ports by default.
you can either configure all of them as VC or as non-vc ports.
To delete VC if you haven't already:
-> request virtual-chassis delete port <> pic <> member <>
Once they non-vc ports, you can use these uplinks port just like your network ports which you connect to end host or switch.
The reason they are called uplinks is becuase each of these uplink 4 ports have seprate dedicated channel to EX-PFE(packet forwarding engine) which gives to higher bandwithd than the other network-ports which has a shared channel to PFE.
Ideally they used to connect core or aggregation switch, but than you can just use those uplink as network/access port as well.