The WiFi essentially is much the same as the cable. You have the access point connected into the office LAN, so using the network cable was superfluous. You have a path for the packets to tranverse to and fro. So unless you configured your access point to filter certain traffic, it will just pass it on as a router is supposed to do.

Basically when you want to talk to another computer, the tcp/ip stack sends out an ARP (address resolution protocol) broadcast asking 'does anybody know about this ip address?' If it doesn't get a response, then you can't talk. Routers keep a track of what devices are connected to it and pass on traffic destined for that address.

You really need to get a good book on tcp/ip to understand the whole goings on - at the low level its quite simple but there a lot going on in the background. Once you understand the basics it all makes sense.