When the critical hormone is released in high enough concentration by the mother's pituitary gland, the mother's uterus begins periodic contractions?

Oxytocin

When the critical hormone oxytocin is released in high enough concentration by the mother's pituitary gland, the mother's uterus begins periodic contraction.

Oxytocin is a peptide hormone produced by the hypothalamus and released into the blood stream by the posterior pituitary. Oxytocin works on certain organs in the body such as the breast and uterus. Oxytocin influences important functions of the reproductive system, including causing contraction of the cervix and uterus during labor, lactation, and sexual reproduction.

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.