Question

during the menstral cycle, what causes both negative and postive feed back? what causes only negative feedback?

a. estradiol, progesterone

b. LH and FSH , estradiol

c. estradiol, LH and FSH

d. progestrone, estradiol

what statement about hemoglobin is correct

a. one hemoglobin binds four O2

b. pO2, adult hemoglobin binds less O2 than fetal hemoglobin

c. myoglobin is greater afdinity than O2

d. pO2, adult hemoglobin binds less than myoglobin

e all are ture

Answer 1

*a

In negative feedback, rising levels of hormones feedback to the hypothalamus and pituitary glandto decrease the production of the hormones.

In positive feedback, rising levels of hormones feedback to increase hormone production.

During most of the menstrual cycle, estrogen and progesterone provide negative feedback to the hypothalamus and pituitary gland.

This keeps their levels more or less constant. During days 12–14, however, estrogen provides positive feedback to the hypothalamus and pituitary gland. This causes a rapid rise in the production of estrogen by the ovaries and leads to ovulation.