Intro to ANS Flashcards

1
Q

what are the 3 branches to the CNS?

A
  • ANS
  • somatic NS
  • neuroendocrine system
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2
Q

what does the ANS act on?

A
  • exocrine glands
  • smooth muscle
  • cardiac muscle
  • metabolism
  • in host defence
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3
Q

what are some targets of the ANS?

A
  • pupillary constriction: constriction mediated by PNS via oculomotor nerve
  • cephalic and gastric phases of digestion: vagal nerve PNS mediation
  • basal HR: PNS dominant at rest
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4
Q

what targets only receive one branch of the ANS?

A

blood vessels

only SNS innervation

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5
Q

what NT do all pre-ganglionic fibres release?

A

ACh

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6
Q

describe the features of the PNS

A
  • long pre-ganglionic
  • short post-ganglionic
  • all transmitters ACh
  • discrete (1:1)
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7
Q

describe the features of the SNS

A
  • short pre-ganglionic
  • long post
  • releases mainly A and NA
  • mass discharge
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8
Q

describe the sensory neurones in the enteric nervous system

A
  • sensory neurons are connected to mucosal chemoreceptors and stretch receptors
  • they detect chemical substances in gut lumen or tension in gut wall caused by food
  • info relayed to submucosal and myenteric plexus by interneurones
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9
Q

describe the motor neurones of the enteric NS

A
  • motor neurones release ACh or Substance P

- contract SM, vasoactive intestinal peptide or NO to relax SM

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10
Q

describe the somatic NS

A

long neurones with eventual ACh release

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11
Q

what are nicotonic receptors?

A
  • found at ALL autonomic ganglia
  • stimulated by nicotine/ ACh
  • type 1 - ionotropic
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12
Q

what are muscarinic receptors?

A
  • found at effector organs innervated by PNS post-ganglionic fibres
  • stimulated by muscarine/ACh
  • type 2: G-protein coupled
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13
Q

what effect would blockade of nicotinic ACh receptors have on HR at rest and then in exercise?

A

Rest: PNS dominant so inc. in HR if PNS blocked
Exercise: SNS dominant so dec. in HR if SNS blocked

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14
Q

what are the subtypes of muscarinic receptors?

A

M1: neural e.g. forebrain (learning and memory) - Gq
M2: cardiac e.g. inhibitory autoreceptors - Gi
M3: exocrine and smooth muscle e.g. hypothalamus - Gq
M4: periphery e.g. prejunctional nerve endings
M5: striatal dopamine release

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15
Q

where are adrenoreceptors found?

A
  • found at all effector organs innervated by post-ganglionic SNS fibres
  • not sweat gland
  • stimulated by NA/A
  • type 2
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16
Q

describe how acetylcholine produced

A

Acetyl CoA + Choline –> ACh + CoA

enzyme: choline acetyl transferase

17
Q

how is it degraded?

A

acetylcholine esterase

18
Q

how is NA/A produced?

A
tyrosine --> DOPA --> Dopamine --> NA (--> via PNMT into A)
enzymes:
tyrosine hydroxylase
DOPA decarboxylase
dopamine beta hydroxylase
19
Q

what are the 2 uptake mechanisms?

A
  1. Monaminde oxidase A (MAO-A)

2. Cathecol-O-Methyl Transferase (COMT)