[Campbell Biology P.1139] A person suddenly encounters a dangerous situation, triggering a ra... | Practice Question

A person suddenly encounters a dangerous situation, triggering a rapid and widespread 'fight-or-flight' response. Which of the following physiological effects would primarily involve direct stimulation by sympathetic preganglionic neurons rather than typical postganglionic neuron activity, leading to a more diffuse, systemic response?

  • A: Increased heart rate and force of contraction.
  • B: Dilation of pupils.
  • C: Release of adrenaline (epinephrine) and noradrenaline (norepinephrine) into the bloodstream from the adrenal medulla.
  • D: Contraction of smooth muscles in the walls of the digestive tract, slowing digestion.

Explanation

As mentioned in the text and hinted by Concept Check 49.1 Q3 , 'the adrenal medulla receives input only from the sympathetic division and only from preganglionic neurons, yet responses are observed throughout the body.' The adrenal medulla then releases adrenaline and noradrenaline into the bloodstream, leading to widespread, systemic effects, unlike the more localized actions of postganglionic neurons on other target organs.