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Systems Neuroscience > Peripheral Nervous System > Flashcards

Peripheral Nervous System Flashcards

1
Q

Spinal Nerves

A 
Spinal Nerves
 - 31 pairs
      8 Cervical (mostly neck muscles and nearby glands)
      12 Thoracic (chest/trunk)
      5 Lumbar (hips and legs)
5 sacral
      1 Coccyx (tailbone)
  • Named for where they enter/exit the spinal column
  • Associated cell bodies are not always at the same level as where the nerve exits/enters
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2
Q

Peripheral Nervous System

A

*Sensory: neurons link the sensory receptors of the body surface or interior with the processing circuits of the CNS
Therefore bringing information TO the CNS

*Motor: two components
Somatic- skin and skeletal muscle
Visceral/Autonomic- organs and smooth muscle
Take information AWAY from the CNS

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3
Q

Somatic *

A

Voluntary movement
Excitatory only
All-or-none response

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4
Q

Autonomic *

  • what type of responses
  • excitatory or inhibitory
  • action type
A

Involuntary action
Excitatory or inhibitory
Graded responses

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5
Q

Autonomic Nervous System is regulated by _____

A

Primarily regulated by the hypothalamus

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6
Q

Hypothalamic Control of the autonomic NS

-project to

A
  • Most important part of the hypothalamus for controlling the autonomic nervous system is the paraventricular nucleus (PVN).
  • Parvocellular (small) neurons in the PVN are dedicated to this. These pre-autonomic parvocellular PVN neurons are project to preganglionic autonomic neurons in:
  • The dorsal motor nucleus of the vagus
  • Autonomic relay nuclei in the brainstem
  • To intermediolateral spinal columns
  • PVN receives afferent inputs from sympathetic (through the trigeminal pars caudalis) and parasympathetic (through the nucleus of the solitary tract) sources
  • Functions as a closed reflex loop system.

*Other parts of the hypothalamus do participate - Dorsomedial nucleus, lateral hypothalamic area, posterior hypothalamic nucleus, and mammillary nuclei

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7
Q

Three major pathways for hypothalamic control ***

A

Three major pathways: the dorsal longitudinal fasciculus, the medial forebrain bundle, and the mammillotegmental tract.

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8
Q

primary pathway of hypothalamic control of autonomic NS

**

A

Dorsal Longitudinal Fasciculus: primary pathway.
PVN –> through periaqueductal gray –> through midline down through brainstem –>through medial spinal cord near area of central canal –> autonomic neurons in brainstem and intermediolateral spinal cord (pre-ganglionic autonomic neurons).

Afferent input from periaqueductal gray, parabrachial nucleus, and locus coeruleus, all of which participate in threat monitoring and behavior to stressors, to the hypothalamus also use this pathway

  • oculomotor cortex (includes Eddinger-westphal nucleus
  • dorsal motor nucleus of the vagus
  • nucleus ambiguus

[: extends the axons- making a stop in the brainstem if need to and make a synapse there (this means trying to control something closer to the brain = the head and neck areas) . If we need to transmit the info farther down then want to synapse in the spinal cord.
Exception of the dorsal motor vagus: we carry connections form the vagus to all of the organs as well]

-primarily an exit pathway but can also send info up it to the hypothalamus-riding the same pathway
(an example of this is the threat monitering)

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9
Q

Locus Coeruleus

- if stimulated

A

If a stimulus is perceived as a threat, a more intense and prolonged discharge of the locus coeruleus activates the sympathetic division of the autonomic nervous system (Thase & Howland, 1995).

Normally, the “firing” of neurons in the locus coeruleus is minimal.
Major noradrenergic nucleus
Arousal, attention, stress responses

*A novel stimulus –> the sensory cortex of the brain through the thalamus to the brainstem –> increases the rate of noradrenergic activity by the locus coeruleus –> alert and attentive to the environment

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10
Q

Medial Forebrain Bundle-

-inputs?

A

Medial Forebrain Bundle-
Fibers from PVN to intermediolateral cell column
*Input to the PVN from septal nuclei and basal forebrain (limbic), as well as visceral afferents by way of the nucleus of the solitary tract

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11
Q

The sympathetic NS: responsibilities

A 
*The sympathetic system is responsible for:
increasing your heart rate
increasing blood pressure
increasing respiratory or breathing rate
regulating your temperature
pupil dilation (enlargement)
bronchial or air passage dilation
decreasing gastric secretions
bladder function (e.g. bladder muscle relaxation, storage of urine)
sexual function
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12
Q

Orthostatic Hypotension ***

A
  • normally occurring drop in blood pressure when standing up.
  • Big shift in blood from trunk to legs
  • Must rapidly adjust so you do not pass out
  • Adapt heart output to compensate
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13
Q

Autonomic Dysreflexia

A

: usually after upper level spinal cord injuries; exaggerated autonomic reflexes (sharp spikes in blood pressure after unmatched stimulus)

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14
Q

Sudden Infant Death Syndrome

A

: possibly a developmental defect in the central autonomic network of the brainstem involved with respiratory drive.

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15
Q

Peripheral Nervous System

composed of

A
  • Nerves- 31 pairs of spinal nerves and your cranial nerves (except for the optic nerve)
  • There are twelve cranial nerves in total
  • Assorted ganglia
  • Basically, anything that exists, at least in part, outside of the brain or spinal cord
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16
Q

Autonomic Nervous System

  • regulated by
  • responsible for:
A

Fight or flight, feed or… breed

Primarily regulated by the hypothalamus

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17
Q

PVN receives:

A
  • of the hypothalamus
  • PVN receives afferent inputs from sympathetic (through the trigeminal pars caudalis) and parasympathetic (through the nucleus of the solitary tract) sources
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18
Q

pre-autonomic parvocellular PVN neurons are project to preganglionic autonomic neurons in:

*

A

These pre-autonomic parvocellular PVN neurons are project to preganglionic autonomic neurons in:

  • The dorsal motor nucleus of the vagus nerve
  • Autonomic relay nuclei in the brainstem
  • To intermediolateral spinal columns
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19
Q

Sensory Input to Autonomic Nervous System

Most of the information will get summed up at :

A

-collecting sensory information form the body so know what is going on in the organs. Most of the information will get summed up at the nucleus of the solitary tract

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20
Q

Hypothalamic Control

receiving what information? and from where?

A
  • contextual information: cerebral cortex, amygdala, hippocampal formation
  • Sensory inputs: visceral and somatosensory pathways, chemosensory and humoral signals

the hypothalamus receives both the contextual information and sensory inputs. Then, it compares input to biological set points.

=>visceral motor, somatic motor, neuroendocrine, behavioral responses

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21
Q

Three major pathways for hypothalamic control:

A

Three major pathways: the dorsal longitudinal fasciculus, the medial forebrain bundle, and the mammillotegmental tract.

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22
Q

what hypothalamus pathway is for threat monitoring

A

Dorsal Longitudinal Fasciculus

Afferent input from periaqueductal gray, parabrachial nucleus, and locus coeruleus, all of which participate in threat monitoring and behavior to stressors, to the hypothalamus also use this pathway

Locus Coeruleus:If a stimulus is perceived as a threat, a more intense and prolonged discharge of the locus coeruleus activates the sympathetic division of the autonomic nervous system (Thase & Howland, 1995).

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23
Q

does the Dorsal Longitudinal Fasciculus have a stop in the brainstem

A

yes

24
Q

is the Dorsal Longitudinal Fasciculus ascending and descending pathway

A

yes

25
Q

Medial Forebrain Bundle

A

Fibers from PVN to intermediolateral cell column
Input to the PVN from septal nuclei and basal forebrain (limbic), as well as visceral afferents by way of the nucleus of the solitary tract
Indirect input from amygdala and hippocampus (through fornix/stria terminalis/ventral amygdalofugal pathway)

  • can send info to and from hypothalamus
  • NO brainstem stop
26
Q

does the Medial Forebrain Bundle have a stop in the brainstem

A

NO

27
Q

is the Medial Forebrain Bundle an ascending and descending pathway

A

Yes

28
Q

Visceral Sensory Information through the Nucleus of the Solitary Tract

A

Nucleus of the Solitary Tract sends the info either to preganglionic neurons (visceral motor response = automatic response) OR to the medial and ventral forebrain for central integration resulting in hormonal and behavioral response

29
Q

Mammillotegmental tract-

A

fibers from mammillary nuclei to target intermediolateral cell column

30
Q

Preganglionic autonomic system***

A
  • Info collected and sent by hypothalamus and brainstem to pre-ganglionic autonomic neurons in spinal cord or brainstem
  • Preganglionic autonomic neurons synapse on lower motor neurons OUTSIDE of the CNS
  • Reside in ganglia near the spinal cord (sympathetic) or are embedded in a neural plexus near the target area (parasympathetic)
  • These lower motor neurons make contact with target (gland, smooth muscle…)
31
Q

*The sympathetic system consists of nerves that are located in :

A

The sympathetic system consists of nerves that are located in the thoracic and lumbar region of the spinal cord between T1-L2 levels.

32
Q

Sympathetic Nervous System: 2 level structure

A

(pre- and post-ganglionic)

33
Q

In the Sympathetic Nervous System: the ones getting all of the info from the hypothalamus and brainstem

A

Preganglionic cell bodies

the Preganglionic cell bodies of the sympathetic system are located in the intermediolateral horn of the spinal cord between T1 and L2 or L3.

34
Q

The sympathetic ganglia location

A

The sympathetic ganglia are adjacent to the spine and consist of the vertebral (sympathetic chain) and prevertebral ganglia, including the superior cervical, celiac, superior mesenteric, inferior mesenteric, and aorticorenal ganglia.

Long fibers run from these ganglia to effector organs, including the smooth muscle of blood vessels, viscera, lungs, scalp (piloerector muscles), and pupils; the heart; and glands (sweat, salivary, and digestive).

35
Q

sympathetic chain

-length

A

Also known as paravertebral
ganglia

22-23 pairs

Run from cervical to sacral

Preganglionic nerves from the
spinal cord synapse at one of
the chain ganglia

Postganglionic fiber extends to
effector, avisceral organ

preganglionic neuron of the spinal cord synapses onto the postganglionic neuron that is found in a sympathetic chain.

  • innervates general somatic structures
  • innervates visceral organs in thoracic cavity
36
Q

t/f the sympathetic chain is within the spinal cord

A

FALSE

37
Q

sympathetic ns: The ganglia interact with the spinal nerves or their ventral rami by means of ___

A

The ganglia interact with the spinal nerves or their ventral rami by means of white and gray rami communicans

38
Q

neurotransmitters of the sympathetic nervous system

A

Onset of a stress response is associated with specific physiological actions in the sympathetic nervous system
Caused by release of epinephrine and norepinephrine from the medulla of the adrenal glands, which is triggered by acetylcholine released from preganglionic sympathetic nerves.
So now we also have E and NE floating around that comes from the adrenal glands
Leads to immediate physical reactions by triggering increases in heart rate and breathing, constricting blood vessels and tightening muscles.
Facilitates spontaneous or intuitive behaviors often related to combat or escape.

39
Q

Epinephrine/Norepinephrine (mostly Norepinephrine)

A

α adrenergic receptors
α1: vasoconstriction (increase blood pressure)
α2: inhibitory to NE, ACh release
β adrenergic receptors
β1: increase heart rate and smooth muscle contraction
β2: does not bind norephinephrine; vasodilation, bronchodilation
[What the epinephrine does to the target really has to do with what receptor is on the target]

40
Q

Acetylcholine

A

*Nicotinic Ach receptors: ligand-gated ion channels that lead to fast EPSPs
[Faster : major flux of ions
May have a faster effect]

*Muscarinic Ach receptors: G protein-coupled receptors; much slower responses; make neuron more excitable and lead to long EPSPs
M1: smooth muscles and gut; slow response; muscle contraction and gland secretion
M2: reduce heart rate; smooth muscle contraction
M3: smooth muscle contraction and gland secretion

41
Q

t/f Acetylcholine always creates long EPSPs

A

FASLE: does not have a singular effect on the cell.

42
Q

Target organs/muscles/glands can have both ___ receptors and ____ receptors

A

Target organs/muscles/glands can have both acetylcholine receptors and adrenergic receptors

43
Q

final effects of Neurotransmitters

A

Final effects depend on sub-types of receptor expressed, which cells are receiving which neurotransmitter, and how the different neurotransmitter receptor pathways are interacting within a cell

44
Q

Parasympathetic Nervous System

A

Control homeostasis
Rest and digest
*The parasympathetic system is responsible for:
slowing your heart rate
bronchial or air passage constriction
increasing gastric secretions
-bladder function (e.g. bladder muscle contraction, release of urine)
bowel function
-sexual function (e.g. erectile function and lubrication)
Longer pathways and slower response than sympathetic nervous system
Resting and digesting is not as time critical as running away from a puma

45
Q

-the _______ NS : has quicker response, shorter pathway

A

-the sympathetic NS : has quicker response, shorter pathway

46
Q

Parasympathetic Spinal Nerves

A

Your parasympathetic division is subdivided into the cranial and sacral sections.
The cranial section consists of the cranial nerves III, VII, IX, X which are located in the lower part of your brain, your brain stem.(!!)
The sacral section is made up of autonomic nerves from the sacral section of your spinal cord, the S2, S3 and S4 levels.

47
Q

-the _______ NS : has more branching

A

sympathetic

48
Q

in regards to the heart/lung:

for the parasympathetic ns the preganglionic fibers vs the postganglionic fibers

A

in regards to the heart/lung:
for the parasympathetic ns the preganglionic fibers (from the brainstem) are very long while the the postganglionic fibers are very short (on the organ)

-making direct contact with the heart and lung using the vagus nerve

49
Q

in regards to the heart/lung:

for the sympathetic ns the preganglionic fibers vs the postganglionic fibers

A

the postganglionic cells are making many stops to get closer to the target

50
Q

Parasympathetic:

-location of motor neurons

A

Parasympathetic:
Motor neurons embedded within plexus close to target
-maybe direct innervation or very close (closer to the actual organ (target) rather than the spinal cord)

Examples: Ciliary ganglion, parasympathetic ganglion

51
Q

-both (symp and parasymp) causes the preganglion release:

A

acetycholine

52
Q

Sympathetic:

-motor neuron location

A

Motor neurons in ganglia close to spinal cord

Examples: sympathetic chain ganglia, celiac ganglion

53
Q

for the postganglionic release

A

Parasympathetic- Postganglionic axon releases acetylcholine

sympathetic: Postganglionic axon releases epinephrine or norepinephrine (adrenaline or noradrenaline)

54
Q

Orthostatic Hypotension: ***

A

normally occurring drop in blood pressure when standing up.
Big shift in blood from trunk to legs
Must rapidly adjust (the output of your heart) so you do not pass out
Adapt heart output to compensate

-autonomic control of cardiovascular function
Example: Rise in blood pressure –> inhibits tonic activity of sympathetic preganglionic neurons and stimulates parasympathetic preganglionic neurons
Example: decrease in blood pressure –> inhibits parasympathetic activity and stimulates sympathetic activity

55
Q

Most important part of the hypothalamus for controlling the autonomic nervous system is the _______

A

Most important part of the hypothalamus for controlling the autonomic nervous system is the paraventricular nucleus (PVN)

56
Q

parasympathetic bladder and sex vs symp

A 
bladder function (e.g. bladder muscle contraction, release of urine)
bowel function
-sexual function (e.g. erectile function and lubrication)

symp

bladder function (e.g. bladder muscle relaxation, storage of urine)

Systems Neuroscience (24 decks)

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