If you use a mobility aid you are likely to undergo additional checks as you proceed to the departure lounge via security. This is because the wheelchair or other mobility equipment could be a place for storing illegal goods. Some passengers will have their clothing swabbed at security and tested. This is a very simple and quick procedure. More information on this and medical implants is available here.
Once through security you arrive at the departure lounge to wait for your Gate number to be announced. The gate is the final waiting area at the airport before you board and can be a considerable distance from the departure lounge. Many airports provide a guide to the distances and times you can expect to travel between the departure lounge and gates. Airport Terminal Maps and MapQuest is useful if you want to know more about your airport.