Field
Medicine
The body as a system to measure and manage — its signals, its chemistry, and the tools that see inside it.
18 articles · 36 widgets
How Muscles Work: Pulling, Never Pushing
Why muscles can only pull and never push, how they work in antagonistic pairs like the biceps and triceps, and how contraction is filaments sliding past each other.
The Heart: Two Pumps in One
How the heart works as two pumps in one — four chambers, one-way valves, the lub-dub of the cardiac cycle, and the figure-eight of double circulation that keeps oxygen-rich and oxygen-poor blood apart.
Digestion: Breaking Food Down to Its Building Blocks
Why most chemical digestion and nearly all nutrient absorption happen in the small intestine, not the stomach — the enzymes, the bile, and the villi that make it possible.
Hormones: The Body's Chemical Messengers
How hormones broadcast slow, body-wide chemical signals through the blood, why only cells with the right receptor respond, and how negative feedback keeps every level in range.
Cancer: When Cell Division Loses Its Brakes
Why cancer is not one disease or one mutation but an accumulation of several, how it jams the accelerator and cuts the brakes, and why it is evolution running inside your own body.
Vaccines: Teaching Immunity in Advance
How vaccines train immune memory using a harmless piece of a pathogen, why the secondary response is fast and strong, and how the herd immunity threshold protects the vulnerable.
How MRI Sees Inside You
Nuclear spins, a resonance condition, and an inverse Fourier transform — how a magnet and a radio antenna build a picture of soft tissue without a single ionising photon.
Pharmacokinetics: How Drugs Clear the Body
First-order elimination, half-life, and accumulation to steady state — the small pile of exponential arithmetic that decides how often a drug has to be taken and how wide its safety margin is.
Antibiotics and Resistance
What antibiotics actually attack, why they do nothing to viruses, the four ways bacteria defeat them, and why a dose that is almost strong enough is the worst dose of all.
Blood Pressure and Circulation
Why a blood-pressure reading has two numbers, how elastic arteries smooth a pulsing heart into steady flow, and why a fourth-power law makes tiny vessels the body's master control valves.
The Kidney: The Body's Filter
The nephron filters almost everything out of the blood by size and pressure, then selectively reabsorbs the water and solutes the body needs — a design that lets one filter handle any waste, keeps the blood's chemistry steady, and sets the rate at which many drugs leave the body.
Breathing and Gas Exchange
How each breath is a passive physics problem: oxygen diffusing down a partial-pressure gradient across the alveolar membrane, loaded onto hemoglobin by an S-shaped curve built for delivery.
Glucose and Insulin: A Feedback Loop
Blood glucose stays inside a startlingly narrow band whether you have just eaten or not eaten for a day. The reason is a negative feedback loop with a sensor, a controller, and an effector — and diabetes is what happens when different parts of that loop fail.
Vision: How the Eye Works
The eye focuses a real, inverted image onto a retina that is sharp only in a tiny central spot and blind where the nerve leaves — and the brain reconstructs the vivid, uniform world you think you see.
How We Hear
How the ear takes one jumbled pressure wave and physically pulls it apart into pure frequencies — a biological Fourier transform curled up inside your head.
Anesthesia: Switching Off Pain and Consciousness
Local anesthetics block the sodium channels that carry the action potential; general anesthesia is a drug-induced state distinct from sleep whose mechanism remains unknown — and both live or die by keeping the concentration in a narrow window.
Epidemic Models and R₀
How three coupled differential equations explain epidemic peaks, why R₀ and Rt are not the same number, and where the herd-immunity threshold actually comes from.
How the Heart's Electrical Signal Works
The electrical pulse that makes your heart beat — traced from origin to muscle contraction.