Blood enters each glomerulus through a tiny afferent arteriole and leaves through an equally tiny efferent arteriole. The filtration pressure that drives fluid and waste out of the blood and into the nephron depends on the balance of resistance between those two vessels — and the kidney can adjust both independently in response to sensed pressure changes. This simulator lets you sweep systemic blood pressure across a wide range and watch both arterioles constrict and dilate in real time, holding glomerular filtration rate almost flat across the normal 80–180 mmHg autoregulatory range. Push blood pressure past either edge of that range and the arterioles run out of room to compensate — GFR then rises and falls directly with blood pressure instead of staying protected, exactly as the live chart's flat plateau and steep flanking slopes show.