Any length of trace will have a specific impedance that depends on the frequency, the characteristics of the copper, the PCB it is on and nearby tracks etc..
Similarly, any component can be thought of as an impedance as well, but you can think of this as an impedance to ground or the supply rail (this is a very broad generalisation).
Therefore if you have a track that goes between just 2 components then you have a 'pi' network with an impedance to ground (say) in parallel to the input at one end, a series impedance going to the next component which is another parallel impedance with the output.
If that track then extends to another component, then you have another series impedance connected to another parallel impedance and so on.
Now, most components are designed to either provide a designed impedance (resistors, inductors etc.) or have a very high impedance (e.g. an op-amp input) which makes then effectively 'disappear' as a load on the track.
Therefore you really need to look at the track you are dealing with and consider the components that are connected to it and the impact they will have on the signal at the frequency you are dealing with.
Susan