ANS and PNS Flashcards

1
Q

SNS

A
  • Thoracolumbar

- Fight or flight

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2
Q

PNS

A
  • Craniosacral

- Rest and digest

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3
Q

SNS effects on the heart

A
  • Stimulation of HR at SA node: + chronotropic effect
  • Stimulation of AV nodal conduction: + dromotropic effect
  • Stimulation of myocardial contractility: + inotropic effect
  • Primarily through activation of B1 adrenergic receptors (epi is the NT)
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4
Q

PNS effects on the heart

A
  • Inhibition of HR at SA node: - chronotropic effect
  • Inhibition of AV nodal conduction: - dromotopic effect
  • Inhibition of atrial contractility (mild): - inotropic effect
  • All via action of muscarinic cholinergic receptors
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5
Q

Propanolol

A
  • B1-adrenergic antagonist

- Used to treat hypertension and tachycardias

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6
Q

Characteristics of SNS 2-synapse pathway

A
  • Short preganglionic fibers
  • Long postganglionic fibers
  • Divergence of preganglionic fivers
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7
Q

Characteristics of PNS 2-synapse pathway

A
  • Long preganglionic fibers
  • Short postganglionic fibers
  • Less divergence of preganglionic fibers
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8
Q

Preganglionic fibers

A
  • Small diameter, slower conducting myelinated B-fibers

- Release ACh that binds to N2 nicotinic cholinergic receptors

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9
Q

Postganglionic fibers

A
  • Small diameter, slower conduction myelinated C-fibers
  • Parasympathetic: ACh binds a muscarinic cholinergic receptors
  • Sympathetic: most use norepi that binds an adrenergic receptor (A or B)
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10
Q

Chromaffin cells

A
  • Of adrenal medulla
  • Directly innervated by SNS
  • Primarily releases Epi, but also some Norepi
  • Hormones carried by the blood to affect other tissues
  • Helps in maintaining blood pressure
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11
Q

Mechanism of A1 adrenoreceptors

A
  • Inactive: aq subunit of Gq protein bound to GDP
  • Active: Norepi bound to A1 receptor, aq subunit bound to GTP
  • aq-GTP then activates PLC–PIP2–DAG + IP3
  • DAG increases PKC, IP3 causes Ca2+ release
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12
Q

Mechanism of B adrenoreceptors

A
  • Inactive: as subunit of Gs protein bound to GDP
  • Active: Norepi bound to B receptor, as subunit bound to GTP
  • as-GTP then activates adenylyl cyclase which then converts ATP to cAMP
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13
Q

Mechanism of nicotinic cholinergic receptors

A
  • ACh opens an ion channel for Na+ and K+

- Receptor has 5 subunits

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14
Q

Mechanism of muscarinic cholinergic receptors

A
  • GPCRs linked to PLC
  • PLC leads to generation of IP3 and DAG
  • Inhibition of adenylate cyclase leading to decreased cAMP
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15
Q

d-Tubocurarine

A

-Antagonist of N1 Nicotinic ACh receptors

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16
Q

Hexamethonium

A

-Antagonist of N2 nicotinic ACh receptors

17
Q

Atropine

A

-Antagonist of M1, M2, M3, M4, M5 muscarinic ACh receptors

18
Q

Pheochromocytoma

A
  • Tumor of adrenal medulla
  • Excessive amounts of norepi (epi too though, rarely dopa)
  • Hypertension
  • Sweating
  • Cold hands and feet
  • Anxiety
  • Palpitations
  • Epigastric pain
  • Tremor
  • Headache
  • Test with assay evaluating metanephrine and free catecholamines
19
Q

Postsynaptic effects of M1, M3, M5 muscarinic cholinergic receptors

A
  • PLC activation
  • Increased intracellular Ca2+
  • Increased DAG
20
Q

Postsynaptic effects of M2, M4 muscarinic cholinergic receptors

A
  • Inhibition of adenylyl cyclase

- Decreased cAMP generation

21
Q

Nuclei of origin for vagus nerve

A
  • Dorsal motor nucleus of vagal nerve

- Medulla

22
Q

Edinger-Westphal nucleus

A
  • Cell bodies of preganglionic fibers traveling with CN3

- Pupillary light reflex

23
Q

Superior salivatory nucleus

A

-Cell bodies of preganglionic fibers traveling with CN7 to pterygopalatine and submandibular ganglia

24
Q

Inferior salivatory nucleus

A

-Cell bodies of preganglionic fibers traveling with CN9 to the otic ganglion

25
Myenteric plexus
- In the gut - Regulates motility--PNS activation is depolarizing and stimulates APs to cause contractions - PNS regulation (SNS inactivation) - Excessive activation: diarrhea - ACh released by PNS nerve terminals - Norepi released by SNS nerve terminals--hyperpolarizes and relaxes muscles, sphincter constriction
26
Submucosal plexus
- Controls GI secretions | - PNS regulation (SNS inactivation)
27
Micturition-Bladder Filling
- SNS dominates - Relaxation of detrusor--B2 - Contraction of internal sphincter--A1 - L1-L3 contributions
28
Micturition-Bladder Emptying
- PNS dominates - Contraction of detrusor--M - Relaxation of internal sphincter-M - S2-S4 contributions