Tag
#physiology
7 articles
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.
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.
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.
How the Heart's Electrical Signal Works
The electrical pulse that makes your heart beat — traced from origin to muscle contraction.