Biological Chemicals in the Body (03:26)
Hormones control nearly everything in the body, but our understanding of them is relatively recent. In this film, endocrinologist John Wass will trace their discoveries through medical history and examine cutting edge endocrine research.
Endocrine System Mystery (04:22)
Farinelli, an 18th century opera singer, was castrated before puberty to maintain his vocal purity. Learn other anatomical differences that resulted from removing the testes. No one understood why they affected so many body parts.
Chicken Castration Experiment (03:35)
In 1849, Arnold Berthold experimented with chickens to learn about castration. He transplanted testes into the abdomens of capons and found they could maintain male characteristics. He deduced that the testes released chemicals that traveled through the blood.
Eternal Youth Experiment (03:38)
Berthold discovered testosterone, but the scientific community ignored his findings. In 1889 at age 72, Charles Brown-Séquard injected a mixture of testicular blood and semen that he claimed rejuvenated him.
Brown-Séquard's elixir peaked medical interest in the healing properties of endocrine glands. His results were likely due to a placebo effect, but the 1890s saw a series of endocrinology breakthroughs.
Victorian Endocrine Experiment (02:33)
Victor Horsley proved that thyroid deficiencies caused cretinism and myxedema. He experimented with transplanting sheep's thyroids into human patients—with short term success.
First Successful Endocrine Therapies (03:45)
Horsley's student George Murray processed sheep's thyroids into a liquid that he injected into patients, with positive results. George Oliver invented an arteriomotor to measure artery diameter. He found that injecting adrenal gland extracts narrowed arteries, increasing blood pressure.
Victorian Oophorectomies (02:04)
In the 19th century, doctors removed women's ovaries to treat mental disorders. They believed the nervous system controlled the body, and that the ovaries were nerve centers; the procedure caused early menopausal symptoms.
Identifying the Endocrine System (03:19)
Josef Halban transplanted ovaries into guinea pigs, where they continued to function—proving they were unrelated to the nervous system and worked through internal chemical secretions. Ernest Starling coined the term "hormones."
Hormone Function (02:23)
Humans possess more than 80 hormones. Each is aimed at a target cell matching its specific chemical structure, and signals that cell to behave in a certain way. Hormones also have different time scales, and can accumulate in the body.
Acromegalic Gigantism (05:03)
Wass' patient Chris Greener suffered a growth hormone overproduction during childhood. In 1909, Harvey Cushing hypothesized that a pituitary gland tumor was responsible for the condition. Wass shrank Greener's tumor and stopped his growth.
Diabetes Mellitus (02:40)
Without insulin production, children couldn't store energy and starved. In the late 19th century, the pancreas was shown to produce insulin and digestive enzymes, which complicated efforts to use the pancreas to produce a diabetes cure.
Pancreatic Insulin Breakthrough (03:00)
Frederick Banting's breakthrough experiments isolated pancreatic insulin in dogs.
Diabetes Treatment (02:12)
In 1921, Banting injected his insulin extract into Leonard Thompson, saving his life. The success inspired medical researchers to try to enhance healthy people by increasing normal hormone levels.
Steinach Operation (03:31)
In the 1920s, men underwent an operation to recapture their youth. Eugen Steinach believed vasectomies would produce more testosterone in the testes. Clients included Yeats, who reported a creative period and increased sexual drive.
Pituitary Gland Function (02:42)
Steinach held a simplistic view of testosterone, but his failure led researchers to discover hormone regulation. The pituitary gland senses when hormone levels are imbalanced and tells glands to adjust accordingly. Recent research uncovered a second regulation system.
Weight Regulation System (03:16)
Professor Sadaf Farooqi discovered a new hormone, leptin, produced by fat cells that set up a feedback loop to the brain to control our appetite. Some patients are unable to produce leptin due to a genetic mutation—proving that obesity isn't always a self-control issue.
Hormone Obesity Treatment (02:45)
Patients unable to control their weight have been successfully treated with leptin. Experts believe more hormones will be discovered in the future; endocrinology is in its infancy.
Credits: The Fantastical World of Hormones (00:36)
Credits: The Fantastical World of Hormones
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