Https://www.sciencelearn.org.nz/resources/1885-body-systems
It has all the answers to every system you need. I didn’t feel like typing it all out. But hope that helps
C. Increases digestibility
Hypothalamic-pituitary-adrenal axis. It's principal effects are increased production of cortisol by the cortex of the adrenal gland.
Because each body system has a completely different function.