Final answer:
Estrogens develop female secondary sex characteristics and assist in endometrial regrowth, ovulation, and menstrual regulation. Progestins prepare and maintain the endometrium for pregnancy and inhibit certain reproductive hormones to prevent ovulation. Estrogen levels fall in the absence of fertilization, triggering menstruation.
Step-by-step explanation:
Basic Actions and Purposes of Estrogens & Progestins
The basic actions of estrogens include the development of female secondary sex characteristics such as breast development, flaring of the hips, and a shorter period necessary for bone maturation. Estrogens also play a role in endometrial regrowth, ovulation, calcium absorption, and the regulation of the menstrual cycle. Conversely, progestins, of which progesterone is a primary example, play a crucial role in preparing the body for pregnancy, maintaining the endometrium to nurture the fertilized egg, and inhibiting the secretion of FSH and LH to prevent ovulation during pregnancy. These hormones also help regulate the menstrual cycle by inducing changes in the endometrium. The stark difference comes during the menstrual cycle, when, in the absence of fertilization, estrogen and progesterone levels drop, triggering menstruation.
During pregnancy, both estrogen and progestin levels remain high to prevent further ovulation and to maintain the pregnancy, with synthetic versions used in birth control to mimic this effect. Importantly, both estrogens and progestins are produced in both males and females, but they are produced in higher quantities in females and are essential for the reproductive system's regulation and the appearance of female secondary sex characteristics at puberty.