R110 ( 2 meg ohm resistor ) blocks the voltage and current of output U12 and goes to another output point
R113 ( 4.99 Meg ohm resistor ) blocks like an open switch from current and voltage looking back
These resistors are called isolation resistors
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I'd be careful with your terms not to confuse the Op.
Those resistors will only 'seem' like an open circuit if the remaining circuit in series has a much lower resistance. It does not 'block' the voltage or current, but significantly
reduces it, again, based on the rest of the circuit.
A 1MegΩ resistor connected in series to a 100KΩ will have 91% of the applied voltage present across itself.. that means that if you attempt to 'block' the voltage from say... 220V AC with a 1MegΩ resistor, the rest of the circuit past the resistor will still see 20V. The higher the resistance of the remaining circuit, the less voltage it will 'block'. Again, this is entirely dependant on the rest of the circuit.
The pics you posted, and referring to 'looking back' is a great reason to use higher value resistors, as they are typically used for feedback. These portions of the circuit must remain mostly stable, and larger values resistors for this will help keep the expected readings in a range that varies very little as the remainder of the circuit changes.. Much like a multi-meter.
When measuring voltage with a multi-meter, you end up putting a MegΩ or so in parallel with the circuit you are measuring, if these did indeed 'block' things or act as open circuits, technicians would not be taught to be able to measure and compensate for the internal resistances of the meters they use. This can
usually be omitted because the change is very slight, but again, it's good to know as there may be a situation where the circuit you are dealing with will not treat a MegΩ like an 'open circuit'