The Reproductive System Chapter 10 Exploring Science 3 rd Edition Ms. O’Rourke

Aim and Objective of the lesson Recall that the menstrual cycle lasts about 28 days and that menstruation occurs at the start of the cycle Understand the following in relation to human reproduction: Fertile period in the menstrual cycle

The menstrual cycle The menstrual cycle diagram P77

The Menstrual Cycle A series of changes that take place in the female body every 28 days.

The Menstrual Cycle In females, one menstrual cycle takes place about every 28 days between puberty and menopause. The menstrual cycle does not take place during pregnancy.

The Menstrual Cycle The following are the average timing of the main events in the menstrual cycle. The timings can be different in females and during different months.

Day 1-5 The lining of the uterus( that has built up during the previous menstrual cycle) breaks down. The lining along with some blood, is passed out of the body through the vagina. This process is called menstruation or having a period. During these days a new egg matures in the ovary.

Days 6-13 A new lining develops in the uterus. The lining is needed to nourish a developing baby if the female is pregnant. Egg continues to develop in the ovary.

Day 14 The egg is released from the ovary. This is called ovulation Ovulation is the release of an egg from the ovary. The egg can survive for 2 days in the fallopian tube.

Day The lining of the uterus remains in place. It will break down on the first day of the next menstrual cycle.

The fertile period The fertile period is the time during the menstrual cycle when a female is most likely to become pregnant ( if she has intercourse) Sperm can stay alive for up to 3 days. This means that pregnancy can occur if the female has intercourse 3 days before ovulation.

The fertile period The egg can stay alive for 2 days. This then means that pregnancy can occur if the female has intercourse 2 days after ovulation.

The fertile period So as a result, the fertile period lasts from day 11 to day 16. This applies to a typical 28 day cycle. However, because menstrual cycles can be shorter or longer in different females, the fertile period is different for every female. In some cycles the fertile period could start as early as day 8 or 9, while in other cycles it could last until day 18 or beyond.