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Year 2: Neurobiology II > Lecture 7: ANS > Flashcards

Lecture 7: ANS Flashcards

1
Q

what is the center of the central autonomic network

A

hypothalamus

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2
Q

what is the hypothalamus responsible for and what nucleus is central to this function

A

role in metabolism and reproduction

paraventricular nucleus is the center

SADPOX

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3
Q

extra-hypothalamus portion of the central autonomic network

A

limbic system as the higher level control system (orbitofrontal cortex, amygdala) = open loop

visceral sensory through brainstem nuclei/SC = closed loop

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4
Q

boundaries of the hypothalamus

A

superior = hypothalamus sulcus (end of sulcus limitans)

posterior (and inferior) = mammillary bodies

inferior = infundibulum

rostral = anterior commissure, lamina terminalis, and optic chiasm

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5
Q

functional zones of hypothalamus

A

anteromedially = parasympathetic/enteric

laterocaudally = cardiovascular/sympathetic

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6
Q

describe the descending tracts of the central auntonomic network

A

tracts are bilateral but ipsilaterally dominant- there are MULTIPLE DECUSSATIONS

3 tracts = major tract, medial forebrain bundle (MFB), and mammillotegmental tract

number of tracts and decussations means that ANS is seldom compromised after a brain injury

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7
Q

what is the major tract

A

the principal pathway or the dorsal longitudinal fasciculus (DLF)

originates in region of paraventricular nucleus of thalamus

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8
Q

what is the medial forebrain bundle

A

descending tract coming from higher control centers like the amygdala, OFC, etc

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9
Q

what is the mammillotegmental tract

A

descending tracts of the central autonomic network

mainly in tegmentum of brainstem

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10
Q

describe a somatic peripheral motor system

A

1 cell system = LMNs in ventral horn

target skeletal mm

synapse at NMJ

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11
Q

descrube a visceral peripheral motor system

A

2 cell system

1st cell for parasympathetic = preganglionic neuron in brainstem or SC (S2-S4)

1st cell for sympathetic = preganglionic neuron in SC (T1-L2)

2nd cell = ganglionic neuron in ganglia/LMN

target = smooth mm/cardiac mm/glands

synapses are bead like along axon terminals

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12
Q

what is divergence in a ganglia

A

one preganglionic axon synapses with multiple second cells

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13
Q

what is convergence in a ganglia

A

multiple preganglionic axons synapse with the same 2nd cell

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14
Q

characteristics of synapses of the visceral motor system

A

beadlike synapses with target organ/cell

within the target organ = gap junctions and synchronized mobility (allows mm to share the same depolarization at same time and avoid incoordination like arrhythmias)

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15
Q

where is the first/preganglionic neuron for the sympathetic arm of the peripheral ANS

A

lateral (aka intermediolateral) horn of SC from T1-L2

located in lamina VII

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16
Q

what is a paravertebral ganglia

A

aka sympathetic ganglia

somata of the 2nd cells

connected to SC and each other

go almost the whole length of the SC

location of synapsis of preganglionic axons with the second neuron

can be at the same segment or ascend/descend to different segments to form the sympathetic chain/trunk

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17
Q

what is a prevertebral ganglia

A

somata of 2nd cell for splanchnic nerve

continuous to the ganglion anterior to the aorta

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18
Q

3 cervical ganglia involved in sympathetic innervation of the head and neck

A

superior
middle (may not exist in some people)
inferior/stellate

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19
Q

how does sympathetic innervation travel in the neck

A

merge into spinal nerves

hike arteries

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20
Q

how does sympathetic innervation travel in the head

A

hike the carotid artery

then hike CN V division branches

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21
Q

Horner’s system can be causes by what

A

compression of sympathetic trunk around the neck

i.e. pancoast tumor in the cupula of the lungs

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22
Q

S&S of horner’s syndrome

A

partial ptosis - due to compromised superior tarsal mm

constriction of pupil - b/c sphincter pupillae (controlled by CN III) still works

red face w/o sweating (paradoxical signs)
- dilation of blood vessels
- lost sweat gland control

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23
Q

for the parasympathetic nervous system arm of the peripheral ANS, where are the 1st and 2nd cells

A

1st/preganglionic neuron = in brainstem AND sacral SC

2nd/ganglionic neuron = closing or directly in target organ

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24
Q

what are the 4 ganglia that can act as 2nd cells for the parasympathetic arm of the peripheral ANS in the head

A

CN III = ciliary ganglia

CN VII = pterygopalantine/submandibular ganglia

CN IX = otic ganglion

25
Q

where is the 2nd neuron for the vagus nerve

A

neck, thoracic to midgut visceral organs

26
Q

where is the 2nd neuron for the pelvic splanchnic nerve (S2-S4)

A

hindgut and pelvis

27
Q

clinically, where is the general location of the sympathetic and parasympathetic arms of the ANS

A

parasympathetic in brainstem

sympathetic in SC

shown in mice

28
Q

independent visceral sensory pathway

A

CN IX: carotid body and sinus

29
Q

blood vessels controlled by parasympathetic nn

A

carotid body and sinus by CN IX; control O2 lvls and BP

arch of aorta by CN X; control BP

30
Q

aside from the visceral sensory of the neck that is independent, where do the rest of the visceral sensory pathways travel

A

they follow visceral motor

some follow CN X from midgut to the caudal solitary nucleus where they synapse and ascend

others follow based on specific spinal cord level
- splanchnic nn for organs in the abdominal/peliv cavity
- spinal nn for thoracic organs, somatic walls, and extremities

31
Q

what is the spinohypothalamic pathway

A

center of visceral motor control

diffuse pain??

32
Q

describe visceral pain (fiber type & change type)

A

mainly through C fibers

diffuse until it touches the somatic wall and irritates a delta fibers

must be fast change, otherwise the pt would adapt to stimuli

33
Q

describe referral pain

A

feel the pain where the visceral senses enter the CNS

internal organs do not match physical location

34
Q

common clinically relevant referral patterns

A

gallbladder = 30-80% population’s follows the R phrenic n

pericardium and parietal pleura in mediastinum follow the phrenic nn in R bicipital groove (R atrium expands with certain heart conditions and thus pain is felt when heart pushes into lungs on R side)

35
Q

compare and contrast sympathetic vs parasympathetic system

A

sympathetic
- increases metabolism
- fight/flight/freeze
-tonic (constant)
- 2nd cell in adrenal gland of medulla; no axons’ directly release epinephrine and norepinephrine
- unique = supply skin, kidney, blood vessels

parasympathetic
- decrease metabolism
- phasic
- rest/digest
- unique = supply ciliary body and sphincter pupillae mm

both = reproduction

36
Q

how does the sympathetic system control body temp

A

decreases body temp via sweating

anterior nucleus of the hypothalamus (parasympathetic function) gives information to the sympathetic system for this to occur

37
Q

how does the sympathetic system control circadian rhythm

A

when light is on
- retinal ganglion neurons activate in superchiasmic nucleus
- inhibition of sympathetic nervous system, no melatonin released, alert and aroused

when light is off
- tonic sympathetic nervous system
- activate pineal gland to release melatonin
- you get sleepy

38
Q

how do neurotransmitters/receptors work in the sympathetic system

A

1st cell releases ACh

binds to nicotonic receptor in post synaptic membrane (ligand gated ionotropic receptors)

2nd cell releases NE as neurotransmitter

amplification occurs by activating the medulla of the adrenal gland which then releases epinephrine and norepinephrine

these then bind to adgrenergic receptors in the target cells (multiple subtypes of alpha or beta metabotropic*)

*metabotropic = diffuse/slow

39
Q

how do neurotransmitters/receptors work in the parasympathetic system

A

1st cell releases ACh

binds to nicotonic receptor in post synaptic membrane (ligand gated ionotropic receptors)

2nd cell still releases ACh as a neurotransmitter

this then binds to muscarinic receptor in the target cells (multiple subtypes of metabotropic receptors)

40
Q

what are cholinergic drugs

A

agonists for parasympathetic nervous system

41
Q

effects of cholinergic drugs

A

pupillary constriction/near vision

salivation

constriction/secretion of bronchi

slow HR

gastric secretion/increased diarrhea

voiding of urine from bladder

42
Q

effects of anticholinergic drugs

A

pupillary dilation/far vision

dry mouth

relaxation/sticky dry bronchi

acceleration of HR

constipation/reduced gastric secretion

retention of urine

43
Q

things to keep in mind with pts with CAD taking cholinergic drugs

A

the meds slow HR but keep in mind other effects it may be having on other parts of the body

44
Q

what are anticholinergic drugs

A

antagonists for parasympathetic nervous system

45
Q

things to keep in mind with pts taking anticholinergic drugs for incontinence

A

inhibits detrusor mm contraction but what other systems are also being affected?

46
Q

what is the enteric nervous system and how can it function independently

A

ANS of GI system

can function independently b/c:
- intrinsic motor/sensory neurons
- independent circuitry
- can be modulated by ANS

often still functions even in a vegetative state

neurons outnumber the number found in the SC

47
Q

what is an interstitial cell

A

pacemaker of the enteric system

allows for rhythm/contractions per min

proximal contracts while distal relaxes; creates rhythm

48
Q

describe the mechanism of peristalsis

A

contraction of proximal intestinal lumen

distension of bolus segment

dilation of distal intestinal lumen

49
Q

why is it important to understand the enteric system and the mechanisms of peristalsis

A

neurotransmitters can get interfered with by pain meds and result in S&S such as constipation or abnormal emotions

50
Q

describe the visceral sensory center and its functional divisions

A

visceral sensory center = solitary nucleus

rostral portion = relays special info about taste

caudal portion = relays all other visceral sensory info

this center cross talks with other regions to allow for reflexes to occur based on sensory input

51
Q

why is the ANS so important

A

maintains major vitals

body temp via the intra hypothalamic nucleus

respiratory rate, HR, and BP in the brainstem

52
Q

how does a normal baroreceptor reflex work

A

maintains BP and prevents it from becoming too high

with body position change blood pools in LE and the reflex increases HR to prevent the BP from getting too low

53
Q

afferent/efferent signals with body position change related to BP

A

afferent (sensory) via CN IX and X from the carotid/aortic sinus

efferent (motor) via CN X for parasympathetic and IML neurons for sympathetic

CN X for visceral motor has 2 nuclei that function differently but synergistically to decrease BP
- Dorsal vagal nucleus decreases cardiac mm contraction
- nucleus ambiguous inhibits sinoatrial node to decrease HR

54
Q

storage phase of bladder control

A

can happen with or without pintine storage descending signals

tonic sympathetic and somatic control

constant relaxation of detrusor mm and contraction of both sphincters

54
Q

describe the control of the urinary bladder

A

bladder wall (detrusor mm/smooth mm)
- sympathetic inhibits
- parasympathetic activates

internal sphincter (visceral motor)
- sympathetic activates
- parasympathetic inhibits

external sphincter (somatic motor)
- via pudendal nn (S2-S4)

*similar control as that of anal sphincters

55
Q

micturition phase of bladder control

A

must activate the micturition center through the reflex

phasic parasympathetic control activation through stretch

contraction of detrusor mm and relaxation of both sphincters

56
Q

AD occurs at what levels

A

T6 and above

57
Q

what happens with AD

A

noxious stimuli induces a reflex with pts that cannot feel below T6

blood vessel constricts below level of injury; cold/pale/goosebumps/sweaty

above injury level is red/hot/no sweat

above the level:
- there is an increase in BP (20-40 mmHg)
- pounding HA
- baroreceptor relfex activated; CN X efferent to decrease HR/cardiac contraction
- blood vessel dilation/flush/no sweat; paradoxical to below lesion

58
Q
A

Year 2: Neurobiology II (10 decks)

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