2-Minute Neuroscience: Parasympathetic Nervous System

Summary

The parasympathetic nervous system, part of the autonomic nervous system, is crucial for energy conservation and processes like digestion. Originating from the brainstem and sacral spinal cord, its preganglionic neurons synapse with postganglionic neurons in ganglia near target organs, primarily releasing acetylcholine. It's often called the 'rest and digest' system, but this term simplifies its complex functions.

Takeaways

• 🧠 The parasympathetic nervous system is part of the autonomic nervous system, controlling automatic processes like digestion and heart rate.
• 🌿 It is often called the 'rest and digest' system due to its role in energy conservation and waste elimination.
• 🔍 The system is an oversimplification and does not fully capture the range of activities of the parasympathetic nervous system.
• 📍 Nerves of the parasympathetic system originate in the brainstem and the sacral spinal cord.
• 🌐 These nerves extend to ganglia, clusters of neurons, before reaching their target organs.
• 🔬 Parasympathetic ganglia are typically located near or within the organs they serve.
• 🛤️ Preganglionic neurons from the brainstem and spinal cord synapse with postganglionic neurons in the ganglia.
• 🚀 Postganglionic neurons then extend to the targets of the parasympathetic nervous system.
• 💊 The primary neurotransmitter released by the parasympathetic system is acetylcholine.
• 🧠🔌 Preganglionic neurons from the brainstem are associated with cranial nerves that innervate the head, neck, and internal organs.
• 🌐📍 Preganglionic neurons from the sacral spinal cord form pelvic nerves, supplying the organs of the pelvis.

Q & A

What is the parasympathetic nervous system?

The parasympathetic nervous system is a subdivision of the autonomic nervous system, which controls automatic processes in the body such as digestion, heart rate, and respiration.

What is the role of the parasympathetic nervous system in the body?

The parasympathetic nervous system is typically associated with energy conservation and processes like digestion and elimination of waste products from the body.

Why is the parasympathetic nervous system sometimes called the 'rest and digest' system?

It is called the 'rest and digest' system because of its association with energy conservation and its role in digestion and waste elimination, although this term is an oversimplification and does not accurately describe its full range of activities.

Where do the nerves of the parasympathetic nervous system originate?

The nerves of the parasympathetic nervous system originate in the brainstem and the sacral spinal cord.

What is the function of ganglia in the parasympathetic nervous system?

Ganglia are clusters of neurons that the parasympathetic neurons extend to first before reaching their targets. The parasympathetic ganglia are typically found near or in the wall of the organs they supply.

What are preganglionic and postganglionic neurons?

Preganglionic neurons are those that travel from the brainstem and spinal cord to the parasympathetic ganglia, where they synapse with postganglionic neurons. Postganglionic neurons then extend to the targets of the parasympathetic nervous system.

Which neurotransmitter do the preganglionic and postganglionic neurons of the parasympathetic nervous system primarily release?

The preganglionic and postganglionic neurons of the parasympathetic nervous system primarily release the neurotransmitter acetylcholine.

Which cranial nerve nuclei give rise to preganglionic neurons in the brainstem?

The preganglionic neurons in the brainstem arise from the cranial nerve nuclei for the oculomotor, facial, glossopharyngeal, and vagus nerves.

What is the role of the vagus nerve in the parasympathetic nervous system?

The fibers that travel with the vagus nerve provide parasympathetic innervation to the head and neck, and also supply the internal organs of the thorax and abdomen.

What are the pelvic nerves and what do they supply?

The pelvic nerves are formed by preganglionic neurons that originate in the sacral spinal cord, and they supply the organs of the pelvis.

How do the parasympathetic preganglionic neurons that originate in the sacral spinal cord differ from those in the brainstem?

The preganglionic neurons originating in the sacral spinal cord come together to form the pelvic nerves, which specifically supply the organs of the pelvis, unlike those in the brainstem that supply the head, neck, thorax, and abdomen.