Bowman ANS Flashcards
What composes peripheral nervous system (PNS)
Somatic nervous system
Autonomic nervous system
What is the somatic nervous system?
Motor and sensory pathways regulating voluntary motor control of skeletal muscle
What is the autonomic nervous system?
Motor and sensory pathways regulating body’s internal environment through involuntary control of organ systems (smooth muscle, cardiac muscle, and glands)
What makes up autonomic nervous system?
- Sympathetic & parasympathetic nervous system<— not always physiologic antagonists
- Enteric system
Where is autonomic nervous system located?
Both in CNS and PNS Coordinates and maintains steady state among the visceral (internal) orgnas
What are preganglionic neurons?
Cell body is located in CNS (myelinated B fibers)
What are postganglionic neurons?
Cell body in autonomic ganglia (unmyelinated C fibers)
What is an example of sympathetic and parasympathetic not being physiological antagonists?
Sympathetic maintains vascular tone but parasympathetic has very little roll in maintaining vascular tone
What autonomic centers activate the ANS?
- Hypothalamus - thermoregulation, regulating visceral behaviors
- Brain stem
- medulla- vasomotor/vasodilator centers
- pons- mecturition (urination)
- Spinal cord
Regulate by sending out long efferent fibers
Where is sympathetic innervation?
Thoracolumbar: preganglionic neurone cell bodies are located in T1-L2/3 of spinal cord
Where are preganglionic neuron cell bodies located in spinal cord in sympathetic innervation?
Intermediolateral horn of grey matter
Where are post-gaglionic neuron cell bodies located for sympathetic innervation?
In ganglia
- Paravertebral chains (either side of psinal column)
- prevertebral ganglia (i.e.- celiac, superior, inferior, mesenteric ganglia in abdomen)
Relative size of preganglionic neurons to post ganglionic for SNS?
Short preganglionic neurons, long post ganglionic
What is baseline function of sympathetic nervous system?
Mobilized energy stores in times of need; “fight or flight” response.
Where do sympathetic nerve fibers leave the spinal cord? Where do they travel initially?
- Nerve fibers leave spinal cord ventrally via the white rami
- They then travel to 22 paravertebral ganglia (sympathetic chain ganglia)
Where can sympathetic nerves travel after the sympathetic chain ganglia?
- Synpase with post-ganglionic neuron at same level OR
- Move caudad or cephalad to synapse at another level
- Pass through ganglia withouth synpasing to collateral ganglia surrounding the abdominal aorta (celiac, superior mesenteric, inferior mesenteric)
- Some ganglia have inhibitory interneurons as well.
Do preganglionic sympathetic neurons in SNS need to synapse with post ganglionic at same level?
No, can move up and down sympathetic chain, so it can go a lot of different places outside of spinal cord
Of the preganglionic nerves that synapse inside sympathetic chain ganglia (aka paravertebral chain), where do the post-ganglionic fibers go? What do they affect?
- Return to spinal nerves via gray ramus (like a highway interchange)
- These postganglionic nerves go on to affect blood vessels, piloerector muscle and sweat glands.
Where do the pre-ganglionic nerves that do not synapse in the sympathetic chain ganglia go?
They go to a peripheral chain ganglion and synapse there with the post-ganglionic fiber.
- The post-ganglionic fiber then exits to travel to various peripheral organs
What is T1 SNS fibers travel to?
Ascend into paravertebral sympathetic chain to head
Where do T2 fibers travel to?
Neck
Where do T3-T6 fibers travel to?
Chest
Where do T7-T11 fibers travel to?
Abdomen
Where do T12-L2 fibers travel to?
Legs
What is distribution of SNS fibers based on?
Embryonic development and NOT spinal segments
What is another name for parasympathetic innervation?
Craniosacral
Where does parasympathetic innervation arise from?
- Cranial (medullary CN 3,7, 9, 10)
- Sacral (spinal cord S2-S4 region)
Where are post-ganglionic neuron cell bodies in PSNS located?
- Target organs
- Discrete ganglia in head and neck (i.e. ciliary ganglia)
What are relative sizes of pre and post ganglion in PSNS
- Long preganglionic neurons
- Short post-ganglionic
What is the parasympathetic function?
Conserve and restore energy
“rest or repose response”
anabolic
Where are most of the PSNS fibers located?
75% of PSNS fibers are in vagus (X) nerve, passing to abdominal and thoracic areas
Where does Vagus nerve innervate in PSNS?
- Heart
- Lungs
- Esophagus
- Stomach
- Small intestine
- liver
- gallbladder
- pancreas
- upper uterus
Where does cranial nerve III innervate for PSNS?
- Edinger westphal nucleus: ciliary muscles of eye
Where does cranial nerve V innervate?
- Submandibular gland
Where does cranial nerve VII innervate for PSNS?
- Superior salivatory nucleus: lacrimal, nasal and submaxillary glands
Where does cranial nerve IX innervate PSNS?
Inferior salivatory nucleus: parotid gland
Where does S2-S3 innervate?
Distal colon, rectum, bladder, lower uterus, external genitalia
What is the ciliary ganglion?
Where preganglionic inpus from Edinger-Westphal nucleus synapse
What is pterygopalatine and submandibular ganglia?
Receive preganglionic input from superior salivatory nucleus
What is otic ganglion
Receive preganglionic input from inferior salivatory nucleus
PSNS is rest for organism but ______ for visceral functions such as digestion
excitatory
What is most important function of SNS?
Vasomotor tone (small degree happening at all times, not just in fight/flight mode)
Sympathetic is amplification response with ____ innervation
Diffuse
Sympathetic controls response to…
- Postural changes
- Exercise
- Emergency massive response (fight or flight)
Parasympathetic Nervous system does ____ and ____ ____ resposnes
Discrete; narrowly targeted
Both parasympathetic and sympathetic nervous system exhibit baseline tone? T/F
True. HR- predominantly vagal predominance
Blood vessels- SNS tone
What receptor types and neurotransmitter in somatic efferent system?
Acetylcholine at nicotinic receptors
What is pre/post neurotransmitter and receptor for blood vessels?
Preganglionic neuron- Ach and nicotinic receptor
Postganglionic- Norepinephrine at andrenergic receptors
What are pre/post ganglionic neurotransmitters and receptor types at sympathetic system for sweat glands?
- Preganglionic- ACh (nicotinic)
- Postganglionic- ACh (muscarinic receptor)
What is neurotransmitter/receptor at adrenal medulla?
- Preganglionic nerve synapses at adrenal medulla with ACh at a nicotinic receptor
- Adrenal medulla produces 80% epinephrine, 20% norepinephrine released by adrenal gland