By the end of this lesson
- Match five hormones to their sources.
- Explain their principal effects.
- Distinguish hormone production from target response.
BIG QUESTION
How can a small chemical signal coordinate distant organs?
Endocrine glands release hormones into blood; only cells with suitable receptors respond.
Metabolic hormones alter fuel availability
The adrenal glands release adrenalineA hormone released by the adrenal glands in danger or stress that increases heart rate and blood glucose, preparing the body for action., increasing heart rate and making more glucose available for fight-or-flight activity.
Pancreatic beta cells release insulinA hormone released by beta cells of the pancreas when blood glucose rises; it lowers blood glucose by making the liver and muscles take up glucose and store it as glycogen. when blood glucose rises. Insulin promotes cellular glucose uptake and glycogen synthesis, lowering blood glucose.
Gonadal hormones coordinate development
The testes produce testosteroneThe male sex hormone made by the testes that causes male secondary sexual characteristics., supporting male secondary sexual characteristics and sperm production.
Ovaries produce oestrogenA female sex hormone made mainly by the ovaries that supports female secondary sexual characteristics and rebuilds the uterus lining in the menstrual cycle., which supports female secondary sexual characteristics and rebuilds the uterine lining.
Progesterone maintains the uterine lining
The corpus luteum in an ovary produces progesteroneA female sex hormone, made by the corpus luteum after ovulation and by the placenta in pregnancy, that maintains a thick uterus lining. after ovulation; the placenta becomes an important source during pregnancy.
Progesterone maintains the uterine lining and inhibits FSH and LH during much of the cycle or pregnancy.
Core hormone map
Learn source, target context and effect together.
| Hormone | Main source | Principal role |
|---|---|---|
| Adrenaline | Adrenal glands. | Fight-or-flight response. |
| Insulin | Pancreatic beta cells. | Lowers blood glucose. |
| Testosterone | Testes. | Male characteristics and sperm production. |
| Oestrogen | Ovaries. | Female characteristics and uterine-lining growth. |
| Progesterone | Corpus luteum/placenta. | Maintains uterine lining. |
Language that earns precision
- endocrine gland
- Gland releasing hormones directly into blood.
- target cell
- Cell with receptors for a particular hormone.
- insulin
- Pancreatic hormone that lowers blood glucose.
- secondary sexual characteristic
- Physical feature developing at puberty but not directly part of gamete production.
Common misconceptions
Claim: Hormones affect every cell equally.
Correction: Only cells with suitable receptors respond directly.
Claim: Insulin converts glucose into glycogen by itself.
Correction: It signals cells and activates pathways that promote uptake and glycogen synthesis.
Claim: Progesterone is produced only in pregnancy.
Correction: The corpus luteum produces it after ovulation in the menstrual cycle.
Match the answer to the command word
Pair each hormone with the correct gland and one specific effect.
Use source → blood → receptor → response.
Recall, apply, then justify
State the source and one effect of adrenaline, insulin and testosterone.
Hint
One source and one role for each hormone.
Suggested marking points
- Adrenaline is released by adrenal glands.
- It prepares the body for fight or flight.
- Insulin is released by pancreatic beta cells.
- It lowers blood glucose.
- Testosterone is produced by testes.
- It supports male secondary sexual characteristics or sperm production.
Explain how insulin lowers blood glucose.
Hint
Signal, uptake and storage.
Suggested marking points
- Insulin binds to receptors on target cells.
- It promotes glucose uptake from blood.
- It promotes conversion of glucose to glycogen, especially in liver and muscle.
Explain why a cell can be exposed to several hormones but respond to only some of them.
Planning hint
Separate transport from recognition.
What a strong design includes
- Many hormones circulate throughout the bloodstream.
- A response requires a complementary receptor.
- Different cell types express different receptors.
- Receptor binding initiates intracellular signalling.
- A cell lacking that receptor does not make the specific response.
- Receptor number and downstream pathways can alter response strength.