Divisions of the nervous system
In this lesson, we’ll explore how the nervous system is organized, breaking it down into its major divisions and learning how they work together to keep the body functioning and responsive.
1) Start with this video:
2) Then, watch these videos:
3) Watch this video for a quick refresher:
4) Finally, answer these questions to test your understanding:
1. You’re home alone watching a horror movie when a sudden jump scare startles you, causing your heart to race. Which division of the nervous system is responsible for this increase in heart rate?
- A. parasympathetic nervous system
- B. enteric nervous system
- C. sympathetic nervous system
- D. somatic nervous system
Show Answer
Correct answer: C
The sympathetic division of the autonomic nervous system is responsible for increasing heart rate during a sudden fright. It prepares the body for “fight-or-flight” by accelerating the heartbeat, increasing respiration, and redirecting blood flow to the muscles.
2. This is the largest and most complex division of the autonomic nervous system:
- A. enteric nervous system
- B. sympathetic nervous system
- C. parasympathetic nervous system
- D. somatic nervous system
Show Answer
Correct answer: A
The enteric nervous system is involved with the regulation of the gastrointestinal tract. It consists of networks of neurons found in the walls of the GI tract and other digestive organs, and it’s thought to contain somewhere between 400-600 million neurons, which would make it the largest and most complex division of the autonomic nervous system.
3. Which neurotransmitter is most commonly released by postganglionic neurons of the sympathetic nervous system?
- A. norepinephrine
- B. dopamine
- C. acetylcholine
- D. serotonin
Show Answer
Correct answer: A
Postganglionic sympathetic neurons typically release norepinephrine, which acts on adrenergic receptors in target tissues. An important exception is sweat glands, where acetylcholine is released instead.
4. The ganglia of the parasympathetic nervous system are typically found:
- A. in a chain that runs alongside the spinal cord
- B. in the dorsal root ganglia
- C. in or very near the walls of the organs they supply
- D. in the cerebral cortex
Show Answer
Correct answer: C
The parasympathetic ganglia are typically found near or in the wall of the organs they supply. The sympathetic ganglia, on the other hand, are typically found much closer to the spinal cord.
5. After a large meal, you relax on the couch and watch a movie. Which of the following divisions of your nervous system would be most active during this period of relaxation?
- A. sympathetic nervous system
- B. parasympathetic nervous system
Show Answer
Correct answer: B
The parasympathetic division promotes “rest and digest” functions (e.g., lowering heart rate and supporting digestion) while the sympathetic division handles “fight or flight.” While you're relaxing on the couch, your parasympathetic nervous system would be more active.
