Hormones & Metabolism
The endocrine loops that set blood sugar, appetite, body clock, growth and reproduction: insulin and GLP-1 after a meal, cortisol and melatonin across the day, the thyroid axis, the menstrual cycle and menopause, and the hormones of pregnancy and lactation. Each one is a feedback loop, and the animations let you break the loop and watch what follows.
Every page here is a hands-on animated diagram, not a video — press play, slow it down, break the mechanism on purpose, and read the live values in real clinical units. They explain how a process works; they are not medical advice, and the evidence for any treatment lives on the topic pages each animation links into.
Table of Contents
The Animations (20)
The Menstrual Cycle: Four Hormones in a Loop
Run the 28-day loop of FSH, LH, estrogen and progesterone — watch a follicle ripen, the LH surge burst the egg, and the lining build and shed — then see how the pill switches the whole loop off.
Launch animation →Growth Hormone: How You Grow (and Why It Stops)
Pulse growth hormone from the pituitary to the liver, make IGF-1, and lengthen bone at the growth plates — then hit puberty, fuse the plates, and see why too much GH means gigantism or acromegaly.
Launch animation →The Stress Response & Cortisol
Fire a stressor: adrenaline spikes in a second, cortisol follows in minutes — then compare an acute stressor with chronic stress and watch the feedback loop blunt.
Launch animation →Brown Fat: How You Burn Calories as Heat
Watch brown-fat mitochondria leak their proton gradient through UCP1 to make pure heat instead of ATP — the uncoupling trick cold switches on, and the dangerous one a banned diet drug forced.
Launch animation →How Insulin Opens the Cell: The GLUT4 Switch
Watch insulin dock a muscle cell and send GLUT4 doors to the surface so glucose pours in — then muffle the signal in insulin resistance, or open the doors with exercise, no insulin needed.
Launch animation →GLP-1, Incretins & How the New Weight-Loss Drugs Work
Eat a meal and watch your gut fire GLP-1 at the pancreas, brain and stomach at once — then see how Ozempic-style drugs resist the enzyme that normally destroys it in two minutes.
Launch animation →The Placenta: Feeding a Baby Before Birth
Watch oxygen, glucose and antibodies cross from mother to baby without their blood ever mixing — and see why the fetal side runs on a clever oxygen-grabbing haemoglobin.
Launch animation →Hunger, Leptin & Why Diets Fight Back
Watch the hunger neurons and the fullness neurons fight it out — then lose weight and see leptin fall, hunger climb, and metabolism drop. It isn't willpower. It's a defended system.
Launch animation →Fertilization: How Sperm Meets Egg
Follow 200 million sperm down to the few hundred that reach the egg, watch the zona harden against the second one — then miss the fertile window by two days and see nothing happen at all.
Launch animation →Inside the Beta Cell: How Insulin Is Released
Zoom inside a single beta cell and watch glucose close the K-ATP channel, calcium flood in, and insulin granules pop out — then force the channel shut with a sulfonylurea, or hold it open with diazoxide.
Launch animation →Your Daily Cortisol Rhythm
Ride the 24-hour cortisol curve from its midnight low to the morning peak that wakes you up — then work a night shift or read the test at the wrong hour and see why timing is everything.
Launch animation →Blood Sugar & Insulin
Eat a meal and watch insulin escort glucose into cells, the liver bank glycogen, and the blood-glucose curve rise and fall — then switch on insulin resistance.
Launch animation →Menopause: Why the Hormones Fall and What Changes
Run a lifetime of ovarian follicles down to zero and watch estradiol swing wildly, then flatten, while FSH climbs — then trigger a hot flash and see the narrowed thermoneutral zone behind it.
Launch animation →Glycation and HbA1c: What That Number Actually Measures
Coat red blood cells in sugar for 120 days and watch HbA1c emerge as their average — then fix the glucose today and see why the number takes months to follow, and when it lies outright.
Launch animation →How Your Thyroid Is Controlled
Run the TSH feedback loop, convert T4 into T3, and set your metabolic rate — then switch on Hashimoto's, Graves', or iodine deficiency and watch the labs move.
Launch animation →Fat Burning & Ketosis
Follow a fatty acid out of a fat cell to the mitochondrial gate — and find it padlocked by insulin. Drop the carbs, open CPT1, and watch the liver start making ketones.
Launch animation →Sleep Stages & Your Body Clock
Run a whole night of deep sleep and REM — then add late-night light, an afternoon coffee, or a nightcap, and watch which parts of the night disappear.
Launch animation →How Breast Milk Is Made: Prolactin & the Let-Down Reflex
Watch a baby’s suckling release two hormones — prolactin to make the milk and oxytocin to squeeze it down in the let-down reflex — then add stress and see the adrenaline shut the let-down off.
Launch animation →Melatonin & the Body Clock
Let darkness raise melatonin and open the gate to sleep — then shine a screen at night to suppress it and delay your clock, fly across time zones for jet lag, or reset it with well-timed light.
Launch animation →Testosterone: The Male Hormone Axis
Follow the GnRH → LH → testosterone chain from brain to testes and watch negative feedback hold it steady — then see what puberty, ageing, and anabolic steroids do to the loop.
Launch animation →