Index
All topics
Everything on the site, in one place. Type to filter. Jump to a category with the chips, or press ⌘K from anywhere to fuzzy-search.
Articles
4 pages- Dopamine, Explained22 minDopamine doesn't make you feel good — it makes you want. The complete guide to the prediction-error neurotransmitter, motivation, addiction, and why the "dopamine detox" is both right and wrong.
- Peptides 10126 minA direct introduction to therapeutic peptides — what they are, what the evidence actually says, which ones have real data vs. marketing, legal status, and how to think about them without getting scammed.
- Sleep Is a Hormonal Event23 minEvery major hormonal axis runs on a sleep schedule. The real cost of sleep debt isn't grogginess — it's measurable testosterone, insulin, cortisol, and growth hormone dysregulation within a week.
- Testosterone: Everything28 minThe definitive guide to testosterone — biology, levels, symptoms, TRT reality, natural optimization, long-term risks, and what the evidence actually says.
Systems
8 pages- Cardiovascular System4 minThe pump and plumbing. A muscle that beats three billion times pushes blood through 60,000 miles of vessels to every cell you own.
- Digestive System4 minA 30-foot tube plus accessory organs that breaks food into molecules small enough to cross a membrane, then pulls them into your blood.
- Endocrine System5 minThe slow, chemical messaging network. Glands dump hormones into blood so distant organs can change their behavior.
- Immune System4 minA distributed defense network that distinguishes self from non-self and eliminates the latter. Fails in two directions — too little, too much.
- Integumentary System4 minYour skin, hair, nails, and glands. The largest organ, the first barrier, and a surprisingly active endocrine participant.
- Musculoskeletal System4 minThe scaffold and motors. Bones give you a frame, muscles move it, and both are more hormonally active than the textbook suggests.
- Nervous System5 minThe fast messaging network. Electrical impulses and chemical synapses, wrapped around a brain and threaded through the body.
- Reproductive System6 minThe anatomy and signaling that produce gametes, run the fertility cycle, and drive sexual response.
Hormones
8 pages- Cortisol10 minThe primary glucocorticoid. Runs a sharp morning rhythm, mobilizes fuel under stress, and wrecks you when chronically elevated.
- Dihydrotestosterone (DHT)10 minThe potent androgen made locally from testosterone by 5-alpha-reductase. Runs male external development, beard, body hair, scalp hair loss, and prostate growth.
- Estrogen10 minThe primary female sex steroid. Estradiol is the active one, and it shapes far more than reproduction — bone, brain, vessels, skin, mood.
- Growth Hormone10 minSomatotropin. Anterior pituitary hormone that drives childhood growth and adult tissue repair — and the most misused "anti-aging" drug in wellness culture.
- Insulin9 minThe anabolic master switch. Pancreatic beta cells release it when fuel is abundant — most metabolic disease is a story of this signal breaking.
- Progesterone10 minThe pro-gestation steroid. Stabilizes the endometrium, maintains pregnancy, modulates GABA, and drops off the cliff in perimenopause.
- Sex Hormone-Binding Globulin (SHBG)9 minThe liver-made carrier protein that decides how much of your sex steroids are actually biologically available. Miss it and you will misread every testosterone lab you order.
- Testosterone12 minThe primary androgen. Runs male development, supports libido and tissue in both sexes, and gets blamed for nearly everything.
Neurotransmitters
2 pages- Dopamine14 minThe pursuit molecule. Not the reward of getting what you want — the signal that makes you work toward it. Drives motivation, movement, and the machinery of addiction.
- Serotonin11 minMostly made in the gut, barely related to brain serotonin. Modulates mood, sleep, appetite, gut motility — and the "chemical imbalance" story is worse than popular framing suggests.
Peptides
2 pages- BPC-15710 minA 15-amino-acid research peptide derived from a gastric juice protein. Impressive rat-model healing data, essentially no human trials, thriving gray-market use.
- Semaglutide13 minA GLP-1 receptor agonist that rewrote obesity medicine. Ozempic and Wegovy are the same molecule, dosed differently. Real weight loss, real side effects, unknown long-term ceiling.
Organs
18 pages- Adrenal Cortex7 minThe outer shell of each adrenal gland. Makes cortisol, aldosterone, and DHEA. The organ "adrenal fatigue" supplements pretend to rescue — and almost never are.
- Adrenal Medulla5 minThe inner core of each adrenal. A modified sympathetic ganglion that dumps epinephrine and norepinephrine into the blood when you need to run.
- Brain7 minRoughly 1.4 kg of lipid and water that runs perception, memory, movement, mood, and every hormonal axis — and remodels itself until you die.
- Heart7 minFour-chambered pump that beats about 100,000 times a day. What actually kills people isn't stress — it's atherosclerosis, quietly built over decades.
- Hypothalamus6 minAlmond-sized chunk of brain that runs body temperature, hunger, thirst, sleep, sex drive, and every major endocrine axis. The real master gland.
- Intestines7 minRoughly 7 meters of small intestine plus 1.5 meters of colon. Where food becomes you, where most of your immune cells live, and where microbiome hype outruns the data.
- Kidneys7 minPaired fist-sized filters running 1 million nephrons each. They process about 180 L of fluid every day to produce 1-2 L of urine — and set your blood pressure while they do it.
- Liver7 minA 1.5 kg biochemical factory running 500+ functions. Capable of regenerating from a fraction of itself — and silently accumulating fat in most adults.
- Lungs6 minTwo elastic sacs of branching airways with a gas-exchange surface the size of a tennis court. Most of their capacity is unused until you need it.
- Ovaries7 minPaired almond-sized gonads that set the timeline for female fertility. Every egg a woman will ever have is present at birth; quality and quantity decline from there.
- Pancreas7 minTwo organs sharing one address — digestive-enzyme factory plus the islets that make insulin and glucagon. Usually silent until it fails catastrophically.
- Pituitary Gland6 minThe master switchboard. A pea-sized gland at the base of the brain that takes hypothalamic orders and runs most of your endocrine system.
- Spinal Cord6 minThe nerve highway between brain and body. About 45 cm long, the width of a thumb, and almost incapable of repairing itself when cut.
- Spleen5 minA fist-sized blood filter and immune reservoir tucked under the left ribs. You can survive without one, but you become permanently vulnerable to specific bacteria.
- Stomach6 minA muscular acid bath at pH 1-2. Denatures protein, kills most pathogens, releases B12-binding intrinsic factor, and is frequently overmedicated into dysfunction.
- Testes6 minPaired male gonads. Two tightly-packed factories running sperm production on one line and testosterone synthesis on the other.
- Thymus5 minThe immune system's training academy. Produces T cells at full power in childhood, shrinks steadily with age, and is mostly fatty remnant by 60.
- Thyroid7 minButterfly-shaped gland at the base of the neck that sets metabolic rate, body temperature, and basically how fast every cell runs.