#15 Parasympathetic Nervous System

The heart beats at around 60 beats per minute.
It would start beating at around 100 beats per minute and that's just at rest.
Part of what keeps your heart under control is your parasympathetic nervous system.
It's often described as the calming side of your automatic system - a kind of antidote to the effects of stress created by the sympathetic system.
The parasympathetic system is why our hearts don't pump so hard that they explode.

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<Comparing Structures of the Smpathetic & Parasympathetic Nervous Systems>

Sympathetic Ganglia:
found closer tothe spinal cord

Parasympathetic Ganglia:
found way out from the spine, near, or even inside, their effector organs

The use of neurotransmitters in the two systems is similar, but not quite the same.
In both systems, neurons release acetylcholine, or ACh, in their preganglionic synapses.
The biggest anatomical difference between these two systems has to do with the physical networks that they form as they reach throughout your body.

Sympathetic Nervous System:
from the thoracolumbar area of your spinal cord

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<What Do Cranial Nerves Do?>
There are 12 of these cranial nerves, and they vary in terms of what kinds of neurons they contain.
Cranial nerves also carry motor fibers that control voluntary functions.
Some of your cranial nerves carry both motor and sensory neurons.

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<The 12 Cranial Nerves>

1. Olfactory Nerve: takes scent information gathered by the nose and sends it to the brain.
2. Optic Nerve: takes visual information gathered by the eyes and sends it to the brain.
3. Oculomotor Nerve: controls four of the six muscles that control the movements of your eyes.
4. Trochlear Nerve: controls just a single muscle of the eye.
5. Trigeminal Nerve: branches into three main starands and innervates the face and jaw muscles
6. Abducens: stimulates some of the muscles in your eyes.
7. Facial Nerve: operates the muscles that make most facial expressions possible.
8. Auditory Nerve: carries sensory information from the cochlea to the brain.
9. Glossopharyngeal Nerve: leads to your tongue and your pharynx.
10. Vagus Nerve: controls the heart and digestive tract among other functions.
11. Spinal Accessory Nerve: has to do with moving your head and shoulders.
12. Hypoglossal Nerve: allows you swallow and talk.

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<Mnemonics & Memory Tips for Studying the 12 Cranial Nerves>

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<Vagus Nerve>
The vagus nerves work as a two-way street, ferrying incoming sensory information from the peripheral system to the brain, and transmitting outgoing motor instructions from the brain to the rest of the body.

• slowing down your heart
• putting some lucose back into storage
• reducing all that norepinephrine that your sympathetic system was pumping out all day