NERVOUS SYSTEM: Parasympathetic Nervous System

Chapter 1: Introduction: Parasympathetic Nervous System

Parasympathetic nervous system keeps the heart under control and prevents it from pumping too hard
Parasympathetic system is the calming side of the autonomic system
Parasympathetic system allows the body to handle digestion, reproduction, waste excretion, and fighting off infections
Parasympathetic system maintains balance in the body

Sympathetic and parasympathetic systems have different functions and structures
Sympathetic ganglia are located near the spinal cord, while parasympathetic ganglia are close to the effectors
Both systems use acetylcholine (ACh) in their preganglionic synapses, but parasympathetic system also releases ACh at synapses with effector organs
Sympathetic system releases norepinephrine at synapses with effector organs
Sympathetic nerves originate from the thoracolumbar area of the spinal cord, while parasympathetic nerves are craniosacral and mostly do not go through the spinal cord

Cranial nerves carry motor and sensory fibers
Some cranial nerves control voluntary functions, while others relay sensory data
Some cranial nerves carry both motor and sensory neurons
Mnemonics are used to remember the names and functions of the 12 cranial nerves

Olfactory nerve: carries scent information from the nose to the brain
Optic nerve: carries visual data from the eyes to the brain
Oculomotor nerve: controls four of the six muscles that move the eyes
Trochlear nerve: controls a single muscle in the eye
Trigeminal nerve: largest cranial nerve, branches into three main strands and innervates the face and jaw muscles
Abducens nerve: stimulates the muscles that move the eyes from side to side
Facial nerve: operates the muscles responsible for facial expressions
Auditory nerve: involved in hearing
Glossopharyngeal nerve: leads to the tongue and pharynx
Vagus nerve: important nerve that should be remembered
Spinal accessory nerve: controls head and shoulder movements
Hypoglossal nerve: allows swallowing and talking, among other functions related to the mouth and tongue

Mnemonics can be used to remember the names and functions of the cranial nerves
Mnemonic examples: "On old Olympus' towering top, a Fin and German viewed some hops" or "Onward old orcs! Toward the Argonath for a Great Villain! Slay Hobbits!"
Teachers often use the sequence of S's, M's, and B's to remember sensory, motor, and both functions
Example mnemonic: "Some say marry money, but my brother says big brains matter more" or "Sorry, Sherlock -- Mean Moriarty Beat Me, But Some Bobbies Busted Moriarty Masterfully!"

The vagus nerve is an important cranial nerve that stretches from the brainstem to visceral organs.
- It connects the brain to organs such as the heart, lungs, and stomach.
The vagus nerve has both sensory and motor functions.
- It carries sensory information from the peripheral system to the brain.
- It transmits motor instructions from the brain to the rest of the body.
The functions of the vagus nerve are mostly automatic and go unnoticed.
The vagus nerve plays a role in the parasympathetic response.
- It sends signals from the stomach to the brain, indicating fullness.
- The brain then sends signals back through the vagus nerve, triggering parasympathetic responses such as slowing down the heart rate and reducing norepinephrine levels.
Eating can be a way to reduce stress and anxiety due to the activation of the vagus nerve.

The parasympathetic system is involved in sexual function.
- It ensures a state of calmness and directs blood flow to the genitals.
The sympathetic system also plays a role in sexual excitement.
The balance between the parasympathetic and sympathetic systems is crucial for effective sexual function.
The rate of action potentials in each division is known as sympathetic tone and parasympathetic tone.
The parasympathetic tone is usually dominant, keeping the sympathetic response in check.
Both the parasympathetic and sympathetic systems are necessary for various bodily functions.

The vagus nerve helps understand how parasympathetic responses work.
Parasympathetic responses are essential for maintaining homeostasis and enabling various activities in life.

The episode was written by Kathleen Yale and edited by Blake de Pastino.
Dr. Brandon Jackson served as a consultant.
The director of the episode is Nicholas Jenkins.
The script supervisor and editor is Nicole Sweeney.
The sound designer is Michael Aranda.
The graphics team is Thought Café.
The episode was co-sponsored by Jennifer K. Koons, Tim Wisard, Mich Acosta, Harry Brisson, David Thompson, Jason Constam, and