C.6.3

=**__Describe the mode of action of oral contraceptives__**=

How do female sex hormones work
At the beginning of the menstrual cycle, the pituitary gland releases the follicle-stimulating hormone (FSH). FSH travels to the ovaries, causing the release of oestradiol, which prepared for the release of an egg from the ovary and the build-up of the uterine wall to accept the egg once it is fertilized.

After about two weeks the luteinizing hormone (LH) is released from the pituitary gland. It travels to the ovaries and releases progesterone which causes the egg to be transported to the uterus, as well as continuing to build up the uterine wall. If the egg is fertilized the egg embeds itself in the uterine wall and hormone levels rises dramatically. If the egg is not fertilized hormone levels fall, and menstruation begins.

The Pill also works by thickening the mucus around the cervix, which makes it difficult for sperm to enter the uterus and reach any eggs that may have been released. The hormones in the Pill can also sometimes affect the lining of the uterus, making it difficult for an egg to attach to the wall of the uterus.

How does the birth control pill work (mode of action of oral contraceptives)
The birth control pill consists of oestadiol / estrogen and progesterone hormones. The increase in the levels of these hormones prevents ovulation, avoiding pregnancy by preventing the attachment of the egg to the wall of the uterus.

BIRTH CONTROL PILLS ~ http://www.avert.org/photo_library/images/normal_photo_no_247.jpg