Question

1) What endocrine organ produces estrogens?

2) how does the absence of thyroid hormones T3 and T4 influence the temperature at which shivering begins why?

Answer 1

1) Estrogen is produced by the Ovary. They are mainly produced by ovarian follicular cells and the a interna in response to Gonadotropin harmones of pituitary gland.

2) Thyroid harmones increase the metabolic rate. They are thermogenic. They stimulate heat production by increasing the metabolic rate. In absence of thyroid harmones, metabolic rates are decreased causing decrease production of heat which are sensed by the hypothalamus. Then hypothalamus stimulates the sympathetic system to constrict vessels and also alternative contract and relax muscle to generate heat. That act is called shivering.