Endocrine System
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98 free Endocrine System trivia questions with answers — science & nature quiz, new questions added Oct 2026.
The endocrine system is the body's slow mail: glands with no ducts dropping hormones straight into the blood to tell distant organs what to do. An almond-sized hypothalamus runs it through a kidney-bean-sized pituitary, and a pine-cone-shaped gland decides when you get sleepy. These 98 questions cover the anatomy and physiology students meet in biology and A&P classes: the major glands and what each secretes, the anterior and posterior pituitary, alpha, beta and delta cells, parathyroid hormone and calcium, the zones of the adrenal cortex, autocrine versus paracrine signaling, and the classic disorders: Cushing's, Addison's, Graves' and goitre. There is history too, from Starling coining 'hormone' to Banting and Best isolating insulin and Leonard Thompson's first injection. Every answer is cited to a page we checked. Play it solo, or print it for a classroom or study-group round.
30 of 98 questions with answers and explanations. Play the quiz
Q 01Endocrine glands release their hormones directly into what?
The bloodstream
The bloodstream: endocrine glands have no ducts, so their hormones travel in the blood to reach target organs far away.
Q 02Which organs make most of a woman's estrogen before menopause?
Ovaries
Ovaries: as their hormone output winds down at menopause, estrogen falls and bone loss speeds up, raising osteoporosis risk.
Q 03Which medical specialty treats diabetes, thyroid disorders and other hormone diseases?
Endocrinology
Endocrinology: an early landmark came in 1849, when Arnold Berthold showed that transplanted testes restored castrated roosters' male traits.
Q 04Which of these hormones is secreted by the thyroid?
Thyroxine
Thyroxine: it helps set the body's metabolic rate, so too little of it leaves people tired, cold and gaining weight.
Q 05Which hormone does the pineal gland secrete?
Melatonin
Melatonin: the gland releases the most in darkness, and light exposure cuts its production, which is how it tracks night and day.
Q 06Glands that signal each other in sequence are often called what?
An axis
An axis: in the HPA axis, cortisol from the adrenal glands inhibits the hypothalamus and pituitary that triggered its release.
Q 07Which hormone does the kidney secrete to stimulate red blood cell production?
Erythropoietin
Erythropoietin: synthetic EPO was among the drugs in the doping that cost Lance Armstrong his seven Tour de France titles.
Q 08Which of these is an exocrine gland rather than an endocrine one?
Salivary
Salivary: mumps typically swells the parotids, the largest salivary glands, which pour saliva into the mouth through a duct.
Q 09The pituitary gland is divided into which two main parts?
Anterior and posterior
Anterior and posterior: the posterior lobe makes no hormones of its own, only storing and releasing ones made in the hypothalamus.
Q 10Which posterior pituitary hormone helps the body retain water?
ADH
ADH: alcohol blocks its release, which is why drinking makes the kidneys let more water out as urine.
Q 11Which hormone induces uterine contractions and stimulates lactation?
Oxytocin
Oxytocin: each contraction triggers the release of more of it, a feedback loop that makes labor contractions stronger and more frequent.
Q 12The parathyroid glands release their hormone in response to low levels of what?
Calcium
Calcium: injury to the parathyroids during thyroid surgery is the most common cause of too little of their hormone, and the low calcium brings on muscle spasms.
Q 13Which pancreatic cells produce glucagon?
Alpha
Alpha: when glucose runs low, their glucagon makes the liver break stored glycogen back down into glucose and release it.
Q 21What does a hormone bind to in a target cell to change its function?
A receptor protein
A receptor protein: a hormone acts only on cells whose receptors fit it, like a key in a lock, so it can reach every tissue yet change only its targets.
Q 22Signaling in which a cell releases a signal that acts only on nearby cells is called what?
Paracrine
Paracrine: the signal is quickly taken up, broken down or trapped close to where it was released, so it acts locally instead of spreading through the body.
Q 23The word 'hormone' comes from a Greek word meaning what?
Setting in motion
Setting in motion: in 1959 two scientists blended it with Greek 'to carry' to coin 'pheromone', a chemical signal that passes between animals.
Q 14Which autoimmune disease destroys the pancreas's insulin-making cells?
Type 1 diabetes
Type 1 diabetes: with those cells gone the body can no longer make its own insulin, so patients depend on insulin injections or a pump to survive.
Q 15In the pancreas, what do the acini secrete?
Digestive enzymes
Digestive enzymes: the acini release them in an inactive form, and pancreatitis strikes when they switch on early and start digesting the pancreas itself.
Q 16What do the pancreatic delta cells produce?
Somatostatin
Somatostatin: it works as a brake on its neighbors in the pancreas, holding back the release of both insulin and glucagon.
Q 17Which disease is caused by hypersecretion of ACTH from a pituitary adenoma?
Cushing's
Cushing's: the extra ACTH drives the adrenals to overproduce cortisol, which rounds the face and builds a fatty hump between the shoulders.
Q 18Which disease results from too little cortisol due to adrenal insufficiency?
Addison's
Addison's: its main danger is an adrenal crisis, a sudden collapse with vomiting and fainting that can bring shock and death if untreated.
Q 19Which disease makes the thyroid overactive, flooding the body with its hormones?
Graves'
Graves': the same autoimmune attack can inflame the muscles and fat around the eyes, which is why some patients' eyes bulge.
Q 20Which type of endocrine disease points to a problem with the pituitary gland?
Secondary
Secondary: the thyroid itself can be healthy, but a failing pituitary stops sending the TSH that switches it on, so the gland goes quiet.
Q 24Who coined the word 'hormone' in 1905?
Ernest Starling
Ernest Starling: a 1903 experiment on a dog by him and Bayliss sparked the Brown Dog affair, a row over animal testing that led to riots in London.
Q 25Which hormone did two London physiologists discover in 1902 while testing whether nerves control the pancreas?
Secretin
Secretin: cutting the nerves did not stop the pancreas responding to acid in the gut, showing that a chemical messenger could carry the signal.
Q 26Where in the body are the S cells whose hormone makes the pancreas release bicarbonate?
The duodenum
The duodenum: its S cells respond to acid arriving from the stomach, and the bicarbonate they trigger keeps that acid from damaging the small intestine.
Q 27Insulin's name comes from the Latin word for what?
Island
Island: the name was coined for the hormone of the pancreas's islets years before anyone managed to isolate it.
Q 28Which two researchers isolated insulin from dog pancreas in Toronto in 1921?
Banting and Best
Banting and Best: with dog surgery too slow to supply enough extract, Banting turned to the pancreases of fetal calves.
Q 29Who worked out the amino acid sequence of insulin?
Frederick Sanger
Frederick Sanger: he gave the exact order of amino acids in both of insulin's chains, backing the idea that a protein's sequence sets its properties.
Q 30Home pregnancy tests work by detecting which hormone in urine?
hCG
hCG: the placenta starts making it once a fertilized egg attaches to the uterus wall.