Ovarian and Uterine Cycles

Ovarian and Uterine Cycles

Ovarian Cycle: This is a cycle where an oocyte will mature,  then erupt from an ovary, and finally travel down the oviduct to the uterus

Uterine cycle: This is when the lining of the uterus grows and prepares for an embryo to implant, but if an oocyte is not fertilized then menstruation occurs (When a girl has their period)

GnRH: Gonadotropin releasing hormone stored in the hypothalamus triggers the release of FSH and LHLH: Luteinizing hormone that is produced by an implanted embryo. When it is released it causes the follicle to release the egg. This process is known as ovulation and then it triggers remaining follicle cells to differentiate into the corpus luteum

FSH: Follicle-stimulating hormone produced in the pituitary gland which stimulates ovarian follicles to grow which begins the secretion of estrogen

Estrogen: There is an increased level of estrogen which serves as a source of positive and negative feedback to regulate the levels of FSH and LH within the body.

Progesterone: Secretion from a follicle that released an egg which is responsible for the thickening of the endometrium and preparing to support embryonic development

hCG: human chorionic hormone which is secreted after the egg has been fertilized and has been detected in pregnancy tests

Positive Feedback Loops: An increase in the hormone levels after the release of an egg into the ovary. This is because more hormones are needed to aid in the proper development of the zygote to a fetus.

Negative Feedback Loops: This is a decrease in the hormone levels within the body which decreases GnRH levels too

Menstruation vs. Pregnancy: Hormone levels are much lower during menstruation than during pregnancy.

Fetal development:

1st trimester: Initially a zygote is turning into an embryo which then turns into a fetus. Organs in the fetus are in their first stages.

2nd trimester: The fetus continues to grow and develop and during this trimester the brain and lungs begin to form

3rd trimester: In this trimester the fetus is growing faster, and at a more rapid pace than the other two trimesters.