Autonomic nervous system Flashcards

1
Q

what is the autonomic nervous system

A

the efferent division if the nervous system which regulates automatic, involuntary events (usually those that involve smooth/cardiac muscle)

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2
Q

what are the 2 subdivisions of the ANS

A

sympathetic; parasympathetic

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3
Q

3 functions of the ANS

A
  • fight or flight (symp)
  • simple involuntary reflexes e.g. pupillary light, salivation etc. (parasymp)
  • maintain negative feedback
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4
Q

what is the enteric nervous system

A

a plexus of nerves around the gut that control its actions (usually still controlled by para/symp)

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5
Q

where is the distribution of sympathetic nerves found in the body

A

T1 - L2 (thoracolumbar outflow)

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6
Q

pre vs post ganglionic nerve fibre length - sympathetic

A

pre ganglionic - short
post ganglionic - long

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7
Q

pre vs post ganglionic nerve fibre length - parasympathetic

A

pre ganglioninc - long
post ganglionic - short

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8
Q

where is the distribution of parasympathetic nerves found in the body

A

cranium + sacrum (separate sections) -> craniosacral distribution

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9
Q

where are the preganglioninc cell bodies of the sympathetic fibres found

A

in the intermediolateral grey column of the SC or in the homologous nuclei of the brain (cranial nerves)

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10
Q

what type of nerve fibres are the preganglionic sympathetic fibres

A

myelinated slow type B fibres

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11
Q

what type of nerve fibres are the post-ganglionic sympathetic fibres

A

usulay unmyelinated type C

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12
Q

where are the pre ganglionic cell bodies (ganglia) found in the parasympathetic system found

A

near/within the target organ

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13
Q

what type of nerve fibres are the preganglionic parasympathetic fibres

A

so myelinated type B fibres

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14
Q

what ANS division is the edinger-westphal nucleus part of

A

paraasympathetic

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15
Q

what is the nucleus tractus solitarus

A

a major sensory nucleus in the dorsal medulla that receives cardiovascular, visceral, respiratory, gustatory, and orotactile information

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16
Q

parasymp innervation of the eye

A

CN III -> ciliary ganglion -> pupillary constriction

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17
Q

parasymp innervation of the lacrimal/salivary glands

A

CN VII/IX -> stimulation of salivary secretion

18
Q

parasymp innervation of the heart

A

CN X -> reduction in heart rate

19
Q

parasymp innervation of the the bronchial tree

A

CN X -> bronchocontriction and stimulation of secretions

20
Q

parasymp innervation of the upper GI tract

A

CN X -> increase in peristaltic rate, relaxation of the sphincters, stimulation of secretions

21
Q

parasymp innervation of the lower bowel, bladder, reproductive organs

A

S2-4 sacral plexus -> contraction of smooth muscle of lower bowel, bladder and relaxation of internal urethra sphincter

22
Q

sympathetic innervation of the eye

A

T1-2 -> superior cervical ganglion -> pupillary dilaition + retraction of the eyelid

23
Q

sympathetic innervation of the lacrimal/salivary glands

A

T1-2 -> inhibition of secretion

24
Q

sympathetic innervation of the heart

A

T1-6 -> increase HR and force of contraction

25
Q

sympathetic innervation of the bronchial tree

A

T3-T6 -> bronchodilation + secretion inhibition

26
Q

sympathetic innervation of the upper GI

A

T5-T12 -> coeliac ganglion -> inhibits peristaltic rate and secretions, sphincter contractions

27
Q

sympathetic innervation of the adrenal gland

A

T6-T11 -> no post ganglionic fibres -> releases adrenaline

28
Q

sympathetic innervation of the skin + peripheral vasculature

A

T8-T11 -> vasoconstriction of skin vasculature, dilation of vessels in muscle, piloerection, sweat secretion

29
Q

sympathetic innervation of the lower bowel, bladder and reproductive organs

A

T9-L2 -> superior + inferior mesenteric ganglion -> inhibits peristalsis

30
Q

how can the CNS control the ANS (4)

A
  1. via the hypothalamus (ventromedial hypothalamus affects sympathetic stimulation);
  2. lateral hypothalamic area (affects parasymp);
  3. Peri Aqueductal Grey (direct/indirect effect);
  4. lower nuclei in brainstem (rostro-ventralmedulla can cause increases sympathetic stimulation to cardio system)
31
Q

what sensory input does not send signals to the nucleus tractus solitarus

A

nociception

32
Q

3 cortical effects on the ANS

A
  1. fear -> fight or flight;
  2. emotional stress/painful stimuli -> vasovagal syncope;
  3. seizures/cardiac death (massive symp. output)
33
Q

what NT is released by preganglionic neurons

A

Ach

34
Q

what receptor type do preganglionic neurons synapse onto

A

nictoinic (ligon gated ion channels) -> N1 in skeletal muscle, N2 in ANS

35
Q

what receptor type do postganglionic parasymp neurons synapse onto (and their subtypes)

A

muscarinic (G-protein coupled) -> there are 5 subtypes: M1/3/5 (PLC mediated), M2/4 (adenyl cyclase mediated)

36
Q

what receptor type do postganglionic sympathetic neurons synapse onto (and their subtypes)

A

adrenergic:
1. alpha 1 (PLC), alpha 2 (adenyl cyclase);
2. beta 1/2/3 (adenyl cyclase)

37
Q

what is the main post ganglionic sympathetic NT

A

noradrenaline

38
Q

what drug activates beta-adrenergic receptors and can be used to treat bradycardia

A

Isoproterenol

39
Q

what ANS systems mediate the pupillary light reflex

A

both
1. parasympathetic -> excitation of the ciliary + sphincter muscles
2. sympathetic -> radial fibers of the iris (dilation)

40
Q

where do the sympathetic fibers of the pupil arise from

A

the thoracic aspect

41
Q

what is the blink and dazzle reflex

A

blink -> relaxaton of the levator palpebrae superialsis (CN III) -> contraction of orbicularis oculi (CN VII)
dazzle ->bright light causes eyelid closure due to afferent nerves from the retina passing to the oculomotor nuclei

42
Q

what nerve is involved in the corneal irritation reflex

A

CN V