Need a hand understanding a section on datasheet example schematic (CYPD3177 USB-C Controller)

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Joined Aug 23, 2019
Hi all. I'm currently designing a circuit using a CYPD3177 USB Type C Controller to change the output voltage of a USB C power supply with power delivery support. I was looking at the example schematic in the datasheet to understand how the chip is used but I'm struggling to get my head around the section with the 2 pairs of MOSFET's that control the power supply output depending on if the chip has successfully negotiated for the desired output from the power supply.

The bit I need help understanding about is the 49.9K resistors and the zener diode. I get that the resistors are there to determine the gate-source voltage of the MOSFET's and the zener diode is there to protect the gate's from being over-volted. The bit that I don't get is how/why the components do that. Would anybody be able to walk me through what goes on in that section of the circuit? Thanks in advance.