The contraceptive pill is a method of birth control that contains hormones similar to those made naturally in a woman's body. The diagram below shows how th...
Question 1 Report
The contraceptive pill is a method of birth control that contains hormones similar to those made naturally in a woman's body. The diagram below shows how the hormones in the pill act on the pituitary gland, which normally releases the hormones FSH and LH that control the ovary. In the diagram the pituitary gland is shown at the top and the ovary at the bottom, joined by an arrow that represents FSH and LH passing from one to the other in the blood. The pill is shown to the side, with a symbol indicating that it blocks the action of the pituitary gland. By affecting the pituitary in this way, the pill changes the normal control of the ovary and so prevents pregnancy. The pill is only one of several different methods that people use to control whether or not a pregnancy occurs. Use the diagram, together with your knowledge of the menstrual cycle and its control, to answer the questions that follow about the pill, the hormones it contains, the way in which it works, and other methods of birth control.
Answer Details
This question is about how the combined contraceptive pill uses hormones and negative feedback to prevent ovulation.
- Meaning of contraception [1]. Contraception is the deliberate prevention of pregnancy, for example by stopping fertilisation or implantation [1].
- Hormones in the pill [2]. Oestrogen [1] and progesterone [1] - the same two hormones the ovary normally makes.
- How the pill acts on the pituitary [3]. As the diagram shows, the pill blocks the pituitary gland: the hormones inhibit the pituitary from secreting FSH and LH [1]; without FSH no follicle develops in the ovary [1]; and without the LH surge no egg is released, so ovulation is prevented [1]. No egg means fertilisation cannot occur.
- The type of control [2]. This is negative feedback [1], because the constantly high level of hormone from the pill is detected and switches off the pituitary's secretion of FSH and LH [1] - the body behaves as though hormone levels are already high enough.
- Other methods of birth control [2]. Another hormonal method: an implant, injection or patch [1]. A barrier (non-hormonal) method: a condom or diaphragm [1].
- An advantage and disadvantages [3]. Advantage: the pill is very reliable and easy to use [1]. Disadvantage: it gives no protection against sexually transmitted infections [1]; and it can cause side effects such as headaches or mood changes [1].
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