Edexcel iGCSE Biology-4.9 Roles of Oestrogen & Progesterone in the Menstrual Cycle- Study Notes- New Syllabus
Edexcel iGCSE Biology-4.9 Roles of Oestrogen & Progesterone in the Menstrual Cycle- Study Notes- New syllabus
Edexcel iGCSE Biology-4.9 Roles of Oestrogen & Progesterone in the Menstrual Cycle- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
4.9 understand the roles of oestrogen and progesterone in the menstrual cycle
Roles of Oestrogen & Progesterone in the Menstrual Cycle
🌟 Introduction
The menstrual cycle is ~28 days long (can vary).
Controlled by hormones that prepare the uterus for pregnancy.
Key female hormones: Oestrogen & Progesterone (from the ovaries).
🌺 Oestrogen
- Produced by: Ovaries (mainly from developing follicle)
- Main roles:
- Stimulates repair & thickening of uterine lining (endometrium) after menstruation
Stimulates release of LH (Luteinising Hormone) from pituitary → triggers ovulation- Inhibits FSH (so only one egg matures at a time)
- Peak: just before day 14 (ovulation)
🌼 Progesterone
- Produced by: Corpus luteum (yellow body formed after ovulation)
- Main roles:
- Maintains thick uterine lining for implantation of fertilised egg
- Inhibits LH & FSH (prevents another egg being released during cycle)
- If no fertilisation: progesterone levels fall → lining breaks down (menstruation)
- If fertilisation occurs: progesterone continues to be secreted to support pregnancy
📊 Summary Table
| Hormone | Secreted by | Role in Menstrual Cycle | Key Timing |
|---|---|---|---|
| Oestrogen | Ovarian follicle | Thickens uterus lining, triggers LH, inhibits FSH | Peaks before ovulation (day ~14) |
| Progesterone | Corpus luteum | Maintains lining, inhibits LH & FSH | Rises after ovulation, drops if no fertilisation |
📌 Quick Recap
– Oestrogen: builds the lining, prepares for ovulation.
– Progesterone: maintains the lining, prepares for pregnancy.
– Falling levels of both → menstruation begins.