The hormone table
The data pages give you the abbreviations and nothing else — what each hormone does, where it comes from and what switches it off is on you. This is that reference, organized by gland, with the feedback loops and the antagonistic pairs that exam questions are built on.
- 1. Every hormone you need
- 2. Tropic hormones and the chain of command
- 3. Feedback, in both directions
- 4. Antagonistic pairs
- 5. The distinctions exams test
Every hormone you need
The idea: learn them by gland. Questions almost always name a gland or a symptom and ask you to supply the rest of the row.
| Gland | Hormone | Main effect |
|---|---|---|
| Hypothalamus | GnRH | Tells the anterior pituitary to release FSH and LH |
| Releasing hormones | Control the rest of the anterior pituitary; also makes ADH and oxytocin, which are stored in the posterior pituitary | |
| Anterior pituitary | FSH | Grows a follicle in the ovary; stimulates sperm production |
| LH | Triggers ovulation and forms the corpus luteum; stimulates testosterone in males | |
| TSH | Stimulates the thyroid to release thyroxine | |
| hGH | Growth of bone and muscle | |
| ACTH, PRL | Adrenal cortex hormones; milk production | |
| Posterior pituitary | ADH | Kidney collecting ducts reabsorb more water — less, more concentrated urine |
| Oxytocin | Uterine contractions in labour and milk release | |
| Thyroid | Thyroxine | Raises metabolic rate |
| Calcitonin | Lowers blood calcium by storing it in bone | |
| Parathyroid | PTH | Raises blood calcium by releasing it from bone |
| Pancreas (islets) | Insulin (beta cells) | Lowers blood glucose: cells take it up, liver stores glycogen |
| Glucagon (alpha cells) | Raises blood glucose: liver breaks glycogen down | |
| Adrenal glands | Adrenaline (medulla) | Fight or flight: heart rate, breathing and blood glucose up |
| Aldosterone, cortisol (cortex) | Sodium and water retention; long-term stress response | |
| Ovaries | Estrogen | Rebuilds the endometrium; triggers the LH surge at high levels |
| Progesterone | Maintains the endometrium after ovulation | |
| Testes | Testosterone (interstitial cells) | Sperm production and male secondary characteristics |
| Placenta / embryo | hCG | Keeps the corpus luteum alive through the first trimester |
Tropic hormones and the chain of command
The idea: a tropic hormone targets another gland rather than a tissue. Most endocrine questions are a three-link chain: hypothalamus → pituitary → gland.
- Thyroid chain: hypothalamus → TSH from the anterior pituitary → thyroxine from the thyroid → metabolic rate.
- Reproductive chain: hypothalamus releases GnRH → FSH and LH from the anterior pituitary → estrogen, progesterone or testosterone from the gonads.
- Non-tropic hormones act directly on tissue: insulin, glucagon, ADH, thyroxine, adrenaline.
Knowing the chain lets you answer questions you have never seen. If a gland at the end of a chain fails, the hormone at the end is low and the tropic hormone above it is high, because nothing is switching it off.
Feedback, in both directions
The idea: negative feedback reverses a change, which is most of homeostasis. Positive feedback amplifies one, and there are only a few examples.
| Loop | Stimulus | Response | Type |
|---|---|---|---|
| Blood glucose | Glucose rises after a meal | Insulin lowers it, which switches insulin release off | Negative |
| Thyroxine | Thyroxine rises | TSH and its releasing hormone fall | Negative |
| Water balance | Blood becomes concentrated | ADH rises, water is reabsorbed, concentration falls | Negative |
| Ovulation | Estrogen climbs past a threshold | It triggers the LH surge instead of suppressing it | Positive |
| Labour | The cervix stretches | Oxytocin causes contractions, which stretch it further | Positive |
Worked: a thyroid tumour produces thyroxine on its own
Thyroxine is high. High thyroxine feeds back negatively on the hypothalamus and anterior pituitary, so TSH is low. The tumour ignores TSH, so thyroxine stays high anyway. High hormone with low tropic hormone points to the gland itself; low hormone with high tropic hormone points to the gland failing.
Antagonistic pairs
The idea: the body controls a value with two opposing hormones, one to push it up and one to bring it down.
| Controlled value | Raises it | Lowers it |
|---|---|---|
| Blood glucose | Glucagon (and adrenaline) | Insulin |
| Blood calcium | PTH | Calcitonin |
| Water retained | ADH, aldosterone | Less ADH — more dilute urine |
A pair means the answer to "what happens next" is rarely "nothing" — if one hormone falls, look for its partner rising.
The distinctions exams test
The idea: a handful of near-misses account for most lost marks in this unit.
- ADH and oxytocin are made in the hypothalamus and only released from the posterior pituitary. The anterior pituitary makes its own.
- FSH and LH do different jobs in each sex — follicle and ovulation in females, sperm and testosterone in males.
- Insulin lowers, glucagon raises. "Glucagon" and "glycogen" are one letter apart: glucagon is the hormone, glycogen is the stored form of glucose.
- At menopause the ovaries stop responding, so estrogen and progesterone are low and, with no negative feedback, FSH and LH are high.
- The pill works by feedback, not by blocking sperm: steady estrogen and progesterone keep FSH and LH down so no follicle matures.
- Anabolic steroids reduce sperm count for the same reason — high testosterone-like levels suppress GnRH, FSH and LH.