I am interested into finding out how PCBs/microcontrollers work.

I am familiar with Arduinos at a pretty high level -- perhaps the computer reads a specific voltage/current from a sensor and translates that into some kind of boolean or other value to respond to. At least that's how I think of it at the moment.

However, I wanted to know exactly how the system communicates? For example, if a sensor is a thermistor, or if it sends voltage values, how does it know to tell the "mind" of the system to respond? Is it all through transistors and logic like that? Basically a signal travels through a series of gates to tell the circuit to do something?

Okay, I want to ask this in the perspective of an example. Suppose there's a system with a 5V supply and a load. Let's say I have a linear thermistor that's 0-10k ohms, and say that the resistance is between 5k and 6k if the temperature is between 90 and 95 degrees Celsius. How would the circuit logic read this and then produce, let's say 10V, as a response? Then switch back to 5V if it's outside that range?

I guess what I'm trying to say is I don't think I exactly understand how the circuitry works (what's involved, what happens) and would definitely like some clarity!!

Thanks so much for reading this.