Compare the differences between the sympathetic and the parasympathetic nervous system.

The sympathetic nervous system is most active in times of stress and acts to increase activity, such as by increasing heart rate, ventilatory rate and dilates pupils. It uses the neurotransmitter noradrenaline, and has many nerves leading out of the CNS. It predominantly has thoracolumbar outflow with short preganglionic fibres and long postganglionic fibres.
The parasympathetic nervous system on the other hand is most active in times of sleep and relaxation, and acts to decrease activity and conserve energy. Its effects include decreasing heart rate, ventilatory rate and constricts pupils. It utilises the neurotransmitter acetlycholine and has few nerves leading out of the CNS. It predominantly has craniosacral outflow with long preganglionic fibres and short post ganglionic fibres.