Pain Withdrawal: Step on Tack 1. Fast protective withdrawal: - Nociceptors fire (~1ms) - Up spinal cord (~10-15ms) - Brainstem reflex arc (~20-25ms) - Down to muscles (~20ms) - Muscle activation (~20ms) - Total withdrawal: ~80ms 2. Conscious awareness: - Signal continues to…
Simplest Reflex: Knee Tap - Stretch sensor in quadriceps (1ms) - Signal to spinal cord L3/L4 (~10ms) - Motor neuron activation back to muscle (~10ms) - Muscle contracts (~20ms) - Total: ~40ms - Never reaches brain - pure spinal loop