The menstrual cycle can be divided up into 4 stages:
Luteal (often know as the Secretory stage)
The entire cycle usually lasts 28 days. It can, however, last for as little time as 21 days or as many as 31. The only interval which is fairly constant in all women is the time from ovulation to the start of menstruation which is almost always 14 or 15 days.
For simplicity sake, I have used the average cycle length throughout my assignment. The main changes occur in the ovaries and uterus and are directed by 4 hormones Lutenising hormone (LH); Follicle Stimulating Hormone (FSH) - both released by the pituitary glands and Oestrogen and Progesterone which are released by the ovaries.
Day 0 of the entire cycle is generally considered to be the first day of your period. This is where you uterus lining breaks down and becomes detached thereby causing bleeding for between 3-5 days. This is known as menstruation. Concurrently, secretion of FSH and LH from the pituitary gland begins to encourage the maturing of an ovarian follicle.
Around the 6th day, the follicle begins to develop. As it grows it starts to produce increasing amounts of oestrogen. This travels through the blood to the uterus and encourages the endometrium lining of the uterus to start to thicken again in preparation of possible fertilization.
Around day 14 the FSH and LH production peaks and the follicle bursts releasing an ovum into the oviduct. This is known as ovulation.
The ruptured follicle which produced the ovum does not simply die it becomes a functioning gland known as a corpus luteum. The corpus luteum produces and secretes progesterone and oestrogen. These hormones help stimulate the development of the uterine lining and they also inhibit the secretion of FSH and LH from the pituit
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