Thermoregulation Homeostasis 3D Simulator

Thermoregulation — 3D

Ambient temperature 20 °C

Exercise / heat load 1.0×

Clothing insulation 0.3 clo

Sweat gain 1.0×

Shiver gain 1.0×

Core temp.

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Error (Tc − Tset)

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Skin blood flow

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Sweat rate

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Shiver heat

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Net heat flux

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How it works

The hypothalamus compares core temperature Tc against a setpoint Tset ≈ 37 °C and drives effectors proportionally to the error, with a small dead-band so effectors don't chatter right at the setpoint. Above setpoint, sweating and vasodilation dump heat; below setpoint, shivering and vasoconstriction conserve and generate it — each response pushes Tc back toward Tset, the definition of negative feedback. Here the skin is built from 24 instanced panels whose color and outward "flush" is driven by vasomotor tone, and real 3D droplets fall under gravity when sweat rate rises.

e = Tc − Tset
sweat  = sweatGain·max(0, e−0.15)      (evaporative loss)
shiver = shiverGain·max(0, −e−0.15)    (metabolic heat)
bloodFlow = clamp(0.5 + e/4, 0, 1)     (vasomotor tone)
dryLoss = G(bloodFlow,clo)·(Tc − Tamb)
C·dTc/dt = M·exercise + shiver·1.2 − dryLoss − sweat·L

Ambient temperature — recolors the environment sphere and the sign of dry heat exchange; above Tc it becomes a heat source the body must fight with sweat alone.
Exercise / heat load — extra metabolic heat the loop has to shed, visible as a hotter internal glow.
Clothing insulation — clo value throttling dry exchange with the room in both directions.
Sweat / shiver gain — effector sensitivity; too low drifts off setpoint under load, too high overshoots and oscillates.
Fever offset — shifts Tset up by 1.5 °C so the same loop now shivers to climb to, then sweats to hold, a higher target.

Real-world relevance: this proportional control loop with saturating effectors is the model behind clinical reasoning about heatstroke, hypothermia and fever, and behind sweat-rate predictions for hot-weather exertion.

Vasoconstricted panel Vasodilated panel Sweat droplet

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