Question

autonomic nervous system fibers are involved in all of the following except_________.
changing the diameter of the pupil
adjusting heart rate and force
altering salivary mucus secretion
regulating gastrointestinal motility
maintaining tonicity of the muscles of the neck

Explanation:

The autonomic nervous system controls involuntary functions. Changing pupil diameter (via iris muscles), adjusting heart rate/force (cardiac muscle), altering salivary mucus secretion (glandular activity), and regulating gastrointestinal motility (smooth muscle in digestive tract) are involuntary. Maintaining neck muscle tonicity involves skeletal muscles (voluntary - somatic nervous system).

Answer:

maintaining tonicity of the muscles of the neck