| Sympathetic nervous system | Parasympathetic nervous system |
| 1. Sympathetic nervous system is formed by 22 pairs of sympathetic ganglia, 2 sympathetic cords which run parallel to vertebral column. | 1. Parasympathetic nervous system has nerve fibres which run along with cranial and spinal nerves. |
| 2. Sympathetic nervous system works through neurotransmitter, adrenaline. | 2. Parasympathetic nervous system works through release of acetylcholine. |
| 3. Sympathetic nervous system enhances all the involuntary functions. | 3. Parasympathetic nervous system retards all the involuntary functions. |
| 4. It brings about fight, fright and flight responses. | 4. It brings about relaxation, comfort, pleasure, etc. |
| 5. The pre-ganglionic nerve fibres are short and the post-ganglionic nerve fibres are long in sympathetic nervous system. | 5. The pre-ganglionic nerve fibres are long and the post-ganglionic nerve fibres are short in parasympathetic nervous system. |
