The parasympathetic nervous system is responsible for the "rest and digest" responses. The sympathetic nervous system, on the other hand, performs the "fight or flight" responses. This question, however, really hinges on knowing the effect of acetylcholine on cardiac muscle. The release of acetylcholine slows the heart rate.

Parasympathetic neurons will only use acetylcholine. Sympathetic neurons signal each other with acetylcholine (preganglionic neurons), but elicit their effects by releasing norepinephrine on their target cells (postganglionic neurons). The effect of norepinephrine on the heart would increase heart rate.

The nervous system has two principle divisions for function and two principle divisions for structure. Structurally, there are the central and peripheral nervous system divisions. Functionally, there are the somatic and autonomic divisions. Within the autonomic nervous system are the sympathetic and parasympathetic divisions.

The somatic nervous system is responsible for voluntary actions, namely the innervation of skeletal muscle. The autonomic nervous system is responsible for all involuntary actions, including smooth muscle contraction, glandular stimulation, and other functions. The parasympathetic nervous system is responsible for the "rest and digest" actions of involuntary organs, increasing digestive and excretory activity. In contrast, the sympathetic nervous system is responsible for the "fight or flight" response, suppressing these activities and stimulating epinephrine release.

Neuroglia are the support cells of the nervous system, and do not conduct action potentials. The central nervous system is composed of only the brain and spinal cord; not nerves. The somatic system controls voluntary movements, so heart rate would not be under its control. The sympathetic nervous system is commonly assigned the "fight or flight" responses, while the parasympathetic nervous system is responsible for "resting and digesting." Since the body is returning to a rested state by lowering heart rate, we would assign this action to the parasympathetic nervous system.

The sympathetic nervous system is responsible for regulating the body's "fight-or-flight" response. Physiological changes produced by the sympathetic nervous system include accelerated heartbeat, dilated bronchi and pupils, glucose breakdown, and inhibited digestion. As a result, when the sympathetic nervous system is active, digestion and its associated involuntary contractions are inhibited—not stimulated.

"Dilated pupils, accelerated heart rate, relaxed bladder" is the correct answer here because it is the only choice is entirely comprised of sympathetic nervous system actions. Some red herrings in the other answers is the fact that constricted pupils is a parasympathetic action, as is stimulation of the salivary gland.

The sympathetic nervous system is one branch of the autonomic nervous system in the body. The autonomic nervous system is not under conscious control. The sympathetic system is responsible for our "fight or flight" response. An increase in heart rate when presented with the dangers of being around a bear is due to the sympathetic nervous system. The increase in heart rate is your body's way of increasing blood supply to the body to help you escape ("flight") from the bear and return to safety.