1. The Menstrual Cycle
Year 8 Science

2. The menstrual cycle refers to the regular monthly changes in the hormones and reproductive organs of females.
The Menstrual Cycle

3. Phases of the Menstrual Cycle

4. The Menstrual Cycle Menstrual Phase
If an egg is not fertilised, the endometrium breaks down. It takes a few days for this blood and tissue lining to pass out of the body.
These events are called a period or menstruation.
The Menstrual Cycle

5. Reproduction in females is controlled by hormones (chemical messengers) that travel in the bloodstream.
These hormones control the:
follicular phase – causes the egg/follicles to mature
ovulation phase - when the egg bursts out of the ovary
luteal phase -thickening of the lining (endometrium)
The Menstrual Cycle

6. Summary 3. Ovulation Phase 4. Luteal Phase 2. Follicular Phase
1. Mensural Phase

7. Stages of the Menstrual Cycle

8. Day 1 starts with the first day of your period
Day 1 starts with the first day of your period. This occurs after hormone levels drop at the end of the previous cycle, signalling blood and tissues lining the uterus (womb) to break down and shed from the body. Bleeding lasts about 5 days.

9. Usually by Day 7, bleeding has stopped
Usually by Day 7, bleeding has stopped. Leading up to this time, hormones cause fluid-filled pockets called follicles to develop on the ovaries. Each follicle contains an egg.

10. Between Day 7 and 14, one follicle will continue to develop and reach maturity. The lining of the uterus starts to thicken, waiting for a fertilized egg to implant there. The lining is rich in blood and nutrients.

11. Around Day 14 (in a 28-day cycle), hormones cause the mature follicle to burst and release an egg from the ovary, a process called ovulation.

12. Over the next few days, the egg travels down the fallopian tube towards the uterus. If a sperm unites with the egg here, the fertilized egg will continue down the fallopian tube and attach to the lining of the uterus.

13. If the egg is not fertilized, hormone levels will drop around Day 25
If the egg is not fertilized, hormone levels will drop around Day 25. This signals the next menstrual cycle to begin. The egg will break apart and be shed with the next period.