Sympathetic vs. Parasympathetic Nerves
Grade 12th Grade · Science · 45 min
What's Included
Learning Objective
I can differentiate between the structures and functions of the sympathetic and parasympathetic nervous systems.
Reading Passage
Sympathetic vs. Parasympathetic Systems
The autonomic nervous system, a division of the peripheral nervous system, regulates involuntary functions through two branches: the sympathetic and parasympathetic nervous systems. These systems maintain homeostasis via largely opposing actions.
The sympathetic nervous system, often called the "fight or flight" system, prepares the body for stress. Its preganglionic neurons originate in the thoracic and lumbar regions of the spinal cord. These short preganglionic fibers synapse with postganglionic neurons located in ganglia near the spinal cord. Postganglionic fibers then extend to target organs. Sympathetic activation increases heart rate and blood pressure, dilates pupils, inhibits digestion, and releases glucose for energy. Neurotransmitters involved include acetylcholine (at the preganglionic synapse) and norepinephrine (at the postganglionic synapse).
Conversely, the parasympathetic nervous system, or "rest and digest" system, conserves energy and promotes relaxation. Its preganglionic neurons originate in the brainstem and sacral spinal cord. These long preganglionic fibers synapse with postganglionic neurons located in ganglia near or within target organs. Postganglionic fibers then have a short distance to travel to the target effector. Parasympathetic activation slows heart rate, decreases blood pressure, constricts pupils, and stimulates digestion. Acetylcholine is the primary neurotransmitter at both pre- and postganglionic synapses.
Guided Notes
3 key concepts
- 1
The sympathetic nervous system, also known as the "fight or flight" system, prepares the body for stress, while the parasympathetic nervous system, or "rest and digest" system, conserves energy and promotes relaxation.
- 2
In the sympathetic nervous system, preganglionic neurons originate in the thoracic and lumbar regions of the spinal cord, whereas in the parasympathetic nervous system, preganglionic neurons originate in the brainstem and sacral spinal cord.
- 3
The neurotransmitter acetylcholine is used at preganglionic synapses in both the sympathetic and parasympathetic nervous systems; however, the sympathetic nervous system uses norepinephrine at its postganglionic synapses, while the parasympathetic nervous system uses acetylcholine at both pre- and postganglionic synapses.
Practice Questions
7 questions · Multiple choice & Short answer
Exit Ticket
Quick comprehension check
“Describe one structural difference and one functional difference between the sympathetic and parasympathetic nervous systems.”
Teacher Guide
Get the complete package:
- Answer keys for all questions
- Differentiation strategies
- Extension activities
- Printable student handouts
