Explain progesterone lining maintenance and pituitary inhibition
Corpus-luteum progesterone → maintained uterine lining, with negative feedback reducing FSH and LH. Decline in progesterone and oestrogen support precedes the next menstruation in a non-pregnant cycle.
Exam scope and assessment notes
Extended only (Supplement) · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recall endocrine glands, blood-borne hormones, ovaries, testes, uterine lining, ovulation and implantation.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What uterine effect is associated with progesterone here?
What you will learn
- Connect corpus-luteum progesterone with maintained lining
- Explain reduced FSH and LH stimulation after ovulation
Original teaching model.
| Feature | Meaning |
|---|---|
| Source | Corpus luteum after ovulation |
| Forward effect | Maintains prepared uterine lining |
| Feedback | Inhibits FSH and LH secretion |
| Decline | Reduced lining support and later shedding |
Connect corpus-luteum progesterone with maintained lining
Progesterone from the corpus luteum helps maintain the prepared uterine lining after ovulation. Oestrogen has helped rebuild the lining; progesterone supports the subsequent maintained state. The distinction between rebuilding and maintenance is useful, although both hormones contribute to the coordinated tissue condition. Progesterone is not the lining itself and does not turn the released egg into that tissue.
Progesterone contributes to negative feedback that inhibits FSH and LH secretion. This reduces stimulation of new follicle development and another ovulation during the post-ovulation phase. Describe inhibition as reduced secretion or stimulation, rather than an absolute claim that every hormone molecule is removed from the blood or the pituitary disappears.
Explain reduced FSH and LH stimulation after ovulation
If pregnancy is not established, corpus-luteum breakdown causes progesterone and oestrogen levels to fall. Loss of hormonal support contributes to uterine-lining shedding. Relief of inhibition permits FSH stimulation to rise for the next cycle. The ovarian source change, blood signal change and uterine response form a causal explanation with different locations.
The original feedback diagram separates the forward effect on the lining from the inhibitory return effect on pituitary signals. In a stipulated model, maintaining progesterone support predicts continued lining support and reduced FSH/LH stimulation; it does not prove pregnancy from a graph alone. Personal hormone treatment and diagnosis are outside this educational relationship.
Pause and explain
What pituitary effect belongs to progesterone feedback?
Worked example
Give two progesterone roles after ovulation.
Show the worked solution
- Name maintenance of uterine lining.
- Name inhibition of FSH and LH secretion.
Answer Progesterone supports maintained uterine lining and inhibits FSH and LH secretion through negative feedback.
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Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the source, target effect and feedback effect of cycle progesterone.
Give me a hint
Use corpus luteum, lining and pituitary hormones.
Compare my reasoning
- Name ovarian corpus luteum and lining maintenance.
- Name inhibition of FSH and LH.
Corpus-luteum progesterone maintains uterine lining and inhibits FSH/LH secretion through negative feedback.
Look for these in your work
- Give source and target
- Include both inhibited signals
Explain how corpus-luteum breakdown connects to menstruation.
Give me a hint
Trace source, signal and uterine response.
Compare my reasoning
- Describe progesterone/oestrogen decline.
- Describe reduced lining support and shedding.
Corpus-luteum breakdown lowers progesterone and oestrogen; loss of support leads to shedding of uterine lining at menstruation.
Look for these in your work
- Give the hormone connection
- Locate shedding correctly
Evaluate “high progesterone on a classroom curve proves a real pregnancy and zero FSH molecules”.
Give me a hint
Separate model relationship from clinical certainty and absolute inhibition.
Compare my reasoning
- Recognise lining-support and inhibitory relationships.
- Reject diagnosis and complete-removal claims.
The curve illustrates support and reduced FSH/LH stimulation; it does not prove real pregnancy or show every FSH molecule has disappeared.
Look for these in your work
- Keep the valid relationships
- Reject both overclaims
Common mistakes
- Inhibition means reduced output, not organ disappearance.
- Maintained support alone is not proof of pregnancy.
What can you explain now?
What pituitary effect belongs to progesterone feedback?
Compare with the explanation
Reduced FSH and LH secretion
It limits further ovarian stimulation.
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Make it stick
Explain connect corpus-luteum progesterone with maintained lining and explain reduced fsh and lh stimulation after ovulation. Follow the event arrows or graph labels before opening the solutions.
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