Family doctor and specialists (Lisbon)

Boa tarde,

Can someone of the experienced members outline for me, how the healthcare system is regarding family doctors and specialists? In the Netherlands, after moving you find your 'own' family doctor (you register ahead, before you get ill) in the direct neighborhood. Is it the same in Portugal? I got the impression that in Portugal, one visits a clinic of family doctors when you are ill and you just deal with the one who is on duty. But I am not sure I got this right.

Thank you in advance!