Investigation of Reproduction and Development in Animals
Due Date: 12/9/96
Cycles, Conception and Contraception
Fertility is the condition of being fertile. The aim of contraception is to inhibit fertility in individuals, hence, slowing population growth. The system by which all female contraception must operate: the menstrual cycle.
What is the menstrual cycle? and what hormones are involved in controlling it?
After puberty, the female produces an egg each month. Other changes take place on a cyclic basis including the uterus lining and hormone levels. These changes are called the menstrual cycle. Follicle stimulating hormone (FSH) from the pituitary gland stimulates the growth of follicles in the ovary. Follicles produce oestrogen that stimulates the pituitary to produce leutinising hormone (LH). As LH increases the size of the follicle increases until an egg is released. The corpus luteum formed in the follicle secretes progesterone that prepares the lining of the uterus for pregnancy. If fertilisation does not occur the lining of the uterus is discharged from the body in the process called menstruation.
What is the birth control pill?
The combined oral contraceptive pill (the pill) is a reversible , hormonal
method of birth control. The pill consists of a mixture of two synthetic hormones similar to oestrogen and progesterone, the woman's natural hormones which regulate the menstrual cycle. The pill is on of the most popular methods of birth control.
How does it work?
The pill basically prevents ovulation, therefore, the ovaries can't release a mature egg. Without an egg for the sperm to fertilize , a woman cannot get pregnant . The hormones also increase cervical mucus, making it difficult for sperm to pass into the uterus.
How effective is the pill?
If used correctly, the pill is highly effective. It has a less than one percent failure rate. However, because many people misuse it, the actual failure rate is more like...
Bibliography: Encarta Encyclopedia, Microsoft 96 ' Kinnear, Judith, Book One: Nature of Biology,
The Jacaranda Press, Sydney, 1992. Winston, Robert, Infertility, A Sympathetic
Approach, Optima Book, Great Britain
, 1994. World Book Encyclopedia, World Book
Inc, Chicago, 1991. The Human Body, World Book Inc, Chicago, 1990.
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