The period marked by the wholesale destruction of the functional zone of the endometrium is

Endometrial ablation (If you are asking what it is)
I don’t know what “period” it is if that’s what your asking (because ive never heard of that)

There are eight major endocrine glands, each with a different function: pituitary gland: the “brain” of the endocrine system; regulates all seven of the other glands and secretes growth hormone.thyroid: regulates a person’s metabolic rate, which is the amount of energy expended daily by a person at rest.thymus: assists in the development of a person’s immune system.adrenal gland: regulates fluid and sodium balance within the body, and secretes epinephrine (“adrenaline”) when the body is under stress, producing the fight-or-flight response.ovaries (in females) and testes (in males): control the development of secondary sex characteristics.pancreatic islets: regulate blood sugar.pineal gland: regulates biorhythms and mood, and stimulates the onset of puberty.

Animals will lose energy because it is converted to heat