By the end of this lesson
- Identify sources of ADH, FSH and LH.
- Explain their principal target effects.
- Apply feedback reasoning to endocrine control.
BIG QUESTION
How does the pituitary coordinate water balance and reproductive cycles?
ADH, FSH and LH act on different targets but all illustrate specific endocrine communication.
ADH conserves water
ADHAntidiuretic hormone: made in the hypothalamus and released from the posterior pituitary, it makes the collecting ducts more permeable to water so more water is reabsorbed. is synthesised in the hypothalamus and released from the posterior pituitary. It acts on kidney collecting ducts.
More ADH increases collecting-duct permeability, increasing water reabsorption and producing a smaller volume of concentrated urine.
FSH supports gamete development
The anterior pituitary releases FSHFollicle-stimulating hormone: released by the anterior pituitary, it makes a follicle (containing an egg) mature in the ovary and promotes oestrogen secretion.. In females it stimulates follicle development and oestrogen secretion; in males it supports sperm production.
Rising ovarian hormones feed back to the hypothalamus and pituitary.
LH triggers gonadal responses
The anterior pituitary releases LHLuteinising hormone: released by the anterior pituitary, its mid-cycle surge triggers ovulation and the formation of the corpus luteum.. In females an LH surge triggers ovulation and supports corpus-luteum formation and progesterone secretion.
In males LH stimulates testosterone production by cells in the testes.
Higher-tier hormone map
Source and target distinguish hormones with different roles.
| Hormone | Source/release site | Key effect |
|---|---|---|
| ADH | Made in hypothalamus; released posterior pituitary. | Increases collecting-duct water reabsorption. |
| FSH | Anterior pituitary. | Follicle/oestrogen development; supports sperm production. |
| LH | Anterior pituitary. | Ovulation/progesterone; stimulates testosterone. |
Language that earns precision
- ADH
- Antidiuretic hormone regulating kidney water reabsorption.
- FSH
- Follicle-stimulating hormone acting on ovaries and testes.
- LH
- Luteinising hormone acting on ovaries and testes.
- ovulation
- Release of a secondary oocyte from an ovary.
Common misconceptions
Claim: The posterior pituitary makes ADH.
Correction: ADH is made in the hypothalamus and stored/released by the posterior pituitary.
Claim: FSH acts only in females.
Correction: It also supports sperm production in males.
Claim: LH is present only at ovulation.
Correction: Its concentration changes and it also acts in males.
Match the answer to the command word
State source, target organ and effect for each hormone.
Write collecting-duct permeability and water reabsorption.
Recall, apply, then justify
State the source and one effect of ADH, FSH and LH.
Hint
Give a release source and a target effect for each.
Suggested marking points
- ADH is released from the posterior pituitary.
- It increases water reabsorption in kidney collecting ducts.
- FSH is released by the anterior pituitary.
- It stimulates ovarian follicle development/oestrogen or supports sperm production.
- LH is released by the anterior pituitary.
- It triggers ovulation/progesterone or stimulates testosterone production.
Explain why more ADH produces concentrated urine.
Hint
Permeability → reabsorption → urine volume.
Suggested marking points
- ADH makes collecting ducts more permeable to water.
- More water is reabsorbed into blood by osmosis.
- Less water remains, so urine volume is lower and concentration higher.
Predict how failure to produce an LH surge would affect the ovarian cycle.
Planning hint
Follow ovulation, corpus luteum and progesterone.
What a strong design includes
- The mature follicle may fail to ovulate.
- An oocyte is not released normally.
- A corpus luteum may not form normally.
- Progesterone secretion after the expected ovulation is reduced.
- The uterine lining is less well maintained in the luteal phase.
- Fertility is reduced because ovulation and cycle timing are disrupted.