What is menstruation? What are the specific actions of FSH, LH, estrogen & progesterone in the menstrual cycle?
During the menstrual phase of the menstrual cycle which starts on the 28th day, the endometrial lining of the female genital tract breaks down due to lack of progesterone As a result bleeding occurs. This monthly flow of blood is called menstruation. During menstrual cycles, the various changes occur in the ovary under the influence of various hormones:- Menstrual phase:- The levels of hormones LH, FSH estrogen & progesterone is very less which results in the breakdown of the endometrial lining of the uterus. Follicular phase:- In this phase, the levels of pituitary hormones FSH & LH increase which causes ovarian hormone estrogen to release, FSH controls the follicular phase, it stimulates the growth of follicles. Both FSH & LH reach their peak level in the middle of the cycle (14th day) Ovulatory Phase:- The level of LH hormones reaching its peak (called LH swing) induces the ruptures of mature Graffian follicle & thereby release of ovum. Luteal phase:- The LH & FSH hormones begin to decline. After ovulation, the follicle ruptures & is transformed into the corpus Luteum which secretes large quantities of progesterone.
