You place raw cookie dough in the hot oven so the dough will cook. What part of this scenario is the
SYSTEM?

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

your spelling is a little off : ]

the endomembrane system i think