Ovarian and Uterine Cycle

Uterine Cycle is more commonly known as the menstrual cycle, which occurs every 4 weeks or so. A woman’s body prepares for pregnancy, but when pregnancy does not occur, blood is released as the woman’s endometrial lining of the uterus sheds. Ovarian Cycle is starts with a development of an oocyte. As it begins to mature, it erupts and travels down the oviduct to the uterus. This cycle is called the ovarian cycle.  GnRH is a hormone that stimulates the brain to produce LH and FSH. LH is also known as the luteinizing hormone, and FSH is also known as the follicle stimulating hormone. These two hormones help control how the body produces a specific sex hormone, called Estrogen. Estrogen is a type of hormone found in women, as well as in men. However, it has a stronger role in women’s bodies as it is the main sex hormone and is vital to the menstrual cycle.  It is known to regulate the menstrual cycle and enriches and thickens the endometrium, ultimately preparing the uterus for pregnancy. Progesterone is a type of hormone that is naturally produced in the ovaries of menstruating women. When a woman is pregnant, this substance is produced by the placenta. Progesterone has numerous roles in a woman’s body. It is often ingested by women in birth control pills, menopausal hormone replacement therapy, or just sometimes to induce a menstrual period or regulate abnormal bleeding problems.hCG comes to play when a blastocyst is embedded in the walls of the uterus. It is during this period when a hormone called hCG comes to play. hCG stands for human chorionic gonadotropin, and is released by the cells around the blastocyst. Its main function is to maintain the corpus luteum in the ovary, preventing the pregnant woman from ovulating.

Positive feedback loops occur when there is an increase in the level of the hormones because of the need of hormones to develop the zygote. Negative Feedback Loops occurs because there is no need for hormones any longer, hence decreasing the GnRH level to limit the release of LH and FSH. An easy way to differentiate between menstruation and pregnancy is the fact that hormone levels are much higher during pregnancy because of the need of hormones to reproduce and develop the fetus.

Fetal Development during the Three Trimesters of Pregnancy:

1^st trimester: Various hormonal changes are taking place in the body. The body begins to prepare itself to nurture the fetus. It is within this period when the baby’s heart starts to beat, and its facial features as well as digestive system are beginning to form.

2^nd trimester: The maximum development of the baby takes place during this period. Most of the major organs are completely formed and start to function in the second trimester of pregnancy.

3^rd trimester: By this time the baby would have fully descended into the pelvis from the abdominal region.