Autonomic Nervous System Flashcards
The autonomic nervous system is the subdivision of the peripheral nervous system that regulates body activities that are generally not under _____ control
conscious
Where do the cell bodies of the somatic nervous system reside?
in the CNS (brain or spinal cord)
Axons of the somatic nervous system extend where and are called what?
They extend all the way to their skeletal muscles as spinal nerves
The autonomic nervous system consist of how many motor neurons? What are they called?
Chains of 2 motor neurons
- first is the preganglionic neuron located in the brain or spinal cord and synapses with the 2nd neuron - second is the postganglionic neuron located in the ganglia outside the CNS and synapse with the organ it serves
Is the pre- or postganglionic neuron slower? Why?
Postganglionic neuron is slower because it is lightly or unmyelinated
What are the 2 divisions of the autonomic nervous system?
- Parasympathetic division
- Sympathetic division
Although the parasympathetic and sympathetic divisions innervate most of the same organs they cause _____ effects
antagonistic
The parasympathetic division is known as what?
The “rest & digest” system
The sympathetic division is known as what?
The “fight or flight” system
The parasympathetic division is aka what and why?
The craniosacral system because all its preganglionic neurons are in the brain stem or sacral levels of the spinal cord
The preganglionic neurons of the parasympathetic division include cranial nerves __, __, __, and __ as well as the lateral horn of gray matter from S_- S_
CN III,VII, IX and X
S2-S4
What does the parasympathetic division innervate?
internal organs (not skin)
What neurotransmitter is released in all pre- and postganglionic parasympathetic neurons?
Acetylcholine
Describe CN III (oculomotor) and its role in the PNS
It constricts the pupils
Describe CN VII (facial) and its role in the PNS
It decreases the production of tears, nasal mucus, and saliva
Describe CN IX (glossopharyngeal) and its role in the PNS
It effects the parotid gland which is a major salivary gland
Describe CN X (vagus) and its role in the PNS
It innervates the visceral organs of the thorax & abdomen:
- stimulates digestive glands - increases motility of smooth muscle of GI tract - decreases heart rate - causes bronchial constriction
The sacral outflow from the parasympathetic nervous system from what nerves?
pelvic splanchnic nerves (S2-S4)
The pelvic splanchnic nerves supply what 2 things?
- the 2nd half of large intestine
- all the pelvic (genitourinary) organs
The sympathetic division is aka what and why?
The thoracolumbar system because all of its neurons are located in the lateral horn of gray matter from T1-L2
Unlike the parasympathetic division, neurons of the sympathetic division go where?
everywhere in the body
7 things associated with the SNS
- nervous sweat
- BP rises during excitement
- dry mouth
- dilated pupils
- increased HR
- increased respiratory rate
- liver release more glucose
What neurotransmitter is released by most postganglionic sympathetic neurons?
Norepinephrine
What neurotransmitter is released by most preganglionic sympathetic neurons?
acetylcholine
Preganglionic axons of the sympathetic nervous system exit the spinal cord where? Where do they enter after they exit the spinal cord?
They exit the spinal cord through the ventral root and enter a spinal nerve
Preganglionic axons of the sympathetic nervous system exit spinal nerves via what?
communicating ramus
As soon as the preganglionic neurons enter the sympathetic trunk/chain what 3 things can they do?
1) Synapse on the postganglionic neuron in chain ganglion then return to spinal nerve and follow its branch to the skin
2) Ascend or descend within the sympathetic trunk, synapse with a postganglionic neuron within a chain ganglion, and then return to a spinal nerve at that level and follow branches to skin
3) Enter the sympathetic chain, pass through without synapsing with a postganglionic neuron, forming a splanchnic nerve that passes towards thoracic or abdominal organs
Where do splanchnic nerves synapse?
In prevertebral ganglion in front of aorta
Once synapsed, where do the postganglionic axons go?
They follow arteries to the organs
