# data[].attributes.body
Regulation of the Cardiovascular, Respiratory and Nervous Systems

# data[].attributes.body
Homeostasis and how the endocrine system maintains a balance

# data[].attributes.attachment_link.readable_text
The pill works as a contraceptive by preventing the fertilization of an egg by a sperm cell. In order to avoid pregnancy, the pill uses hormonal mechanisms to keep the sperm and the egg apart and to stop the release of an egg (ovulation). For this to work properly, the pill needs to be taken around the same time every day. Researchers found a way to redirect naturally occurring hormones of the menstrual cycle by utilizing synthetic analogues to those hormones. We will explain the combination pill which contains estrogen and progestogen as active ingredients in varying formulations like synthetic estrogens and progestin.

Progestogens are a group of hormones with progesterone as the most important naturally occurring member. The progestogen that is used in the pill is the synthetic progestin such as drospirenone or levonorgestrel. The estrogen contained in the pill is also a synthetic variant, usually ethinylestradiol.

The hypothalamic-pituitary-gonadal (HPG) axis regulates the production and release of the hormones that are involved in the menstrual cycle and necessary for reproduction see Chapter I of the series.

By introducing synthetic variants of hormones to the blood, estrogen and progesterone feedback to the hypothalamus and the pituitary leading to decreased release of LH and FSH. The decrease of FSH levels leads to impaired follicular development. The lack of the mid-cycle LH surge results in missing ovulation. By suppressing the naturally stimulating signals, the pill prevents egg maturation and ovulation.

# data[].attributes.attachment_link.description
The pill works as a contraceptive by preventing the fertilization of an egg by a sperm cell. In order to avoid pregnancy, the pill uses hormonal mechanisms to keep the sperm and the egg apart and to stop the release of an egg (ovulation).