A car pulls out in front of you and you brake hard. Order what your nervous system does, from the first signal to the return to baseline.

1. Visual information reaches the brain and the threat is registered.
2. Sympathetic outflow surges: heart rate up, pupils wide, blood to the muscles.
3. The adrenal medulla adds adrenaline to the bloodstream, sustaining the response.
4. The danger passes and sympathetic outflow ceases.
5. Parasympathetic activity restores the resting balance over the next several minutes.

The last two steps are where the interesting asymmetry lies. Sympathetic nerve traffic stops the moment the threat does, but the adrenaline already circulating has no off-switch and must be metabolised - which is why you are still trembling a minute after the car has gone.

That is the practical difference between the two delivery routes. Direct sympathetic innervation is fast and terminates cleanly; hormonal delivery is slower to start and much slower to end, and it is what turns a half-second event into several minutes of physiology.

Recovery is also not passive. Returning to baseline is active parasympathetic work, and how quickly someone accomplishes it is a meaningful individual difference - people whose recovery is slow spend more of their day in a mobilised state, which is the physiological route by which repeated acute stress becomes chronic.