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Pharm 1 > ANS > Flashcards

ANS Flashcards

1
Q

Where are the SNS nerves located?

A

T1-L2

Preganglia near the spinal cord

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2
Q

What do the post ganglia nerves do in the SNS?

A

Secrete nor-epi—> adrenergic fibers

  • dopamine enters synaptic vessel
  • dopamine beta hydroxylase converts dopamine to norepinephrine
  • an action potential releases norepinephrine from the synaptic vessel
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3
Q

How is a norepinephrine signal terminated?

A
  • re-uptake
  • dilution by diffusion
  • metabolism: monoamine oxidase (MAO) and catecholamines-o-methyl transerase (COMT)
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4
Q

How does SNS stimulation work on a cellular level?

A
  • works on G coupled protein mechanism (not ion gated channel)
  • activates adenolate-cyclase—> ∆es ATP into cAMP
  • PDE3 stops mechanics of cAMP
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5
Q

What is the Alpha 1- post synaptic reaction?

A

** flight or flight
- activation increases intracellular Ca++
—> smooth muscle contraction and peripheral vasoconstriction
- bronchoconstriction: not what we want (ß-2= bronchodilation)
- inhibits insulin secretion
- stimulates glucogenolyis and gluconeogenesis
- mydriasis
- GI relaxation

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6
Q

What does Alpha 2 stimulation do?

A
  • negative feedback loops*
  • presynaptic in PNS
    • decreased Ca entry into cell
    • limits release of norepinephrine —> says “we’ve had enough”
  • Post synaptic in CNS: (precedex)
    • sedation
    • decreased sympathetic outflow
    • hypotension
    • platelet aggregation
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7
Q

What happens with ß-1 stimulation at the postsynaptic receptor?

A

(ß-blockers block this)

  • primarily the HEART
  • increases HR, conduction velocity, and myocardial contractility
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8
Q

What happens we ß-2 stimulation occurs at the postsynaptic receptor?

A

(Balances alpha)

  • stimulation leads to smooth muscle relaxation
  • peripheral vasodilation
  • decreases BP
  • Bronchodilation.
  • increases insulin secretion
  • increases glycogenolysis and gluconeogenesis
  • decreases GI motility
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9
Q

What is true regarding PNS?

A
  • cranio-sacral nerve origin: CN III, V, VII, X and sacral nerves 2,3,4
  • preganglia:near origins of innervation
  • post-ganglia secrete ACH—> cholinergic fibers
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10
Q

What does acetylcholine (Ach) do?

A
  • activates both arms of ANS
  • choline + acetylcholine CoA—> acetylcholine
  • Ca mediated action potential
  • deactivated by AchE
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11
Q

What are the cholinergic receptors?

A

Nicotinic

Muscarinic

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12
Q

What happens to the heart with SNS and PNS stimulation?

A

SNS stim:

  • increases HR and conduction velocity
  • increases automaticity and contractility

PNS stim:
- decreases HR, conduction velocity and slightly decreases contractility

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13
Q

What happens to bronchial smooth muscle with SNS and PNS stimulation?

A

SNS stim:
- relaxation

PNS stim:
- contraction

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14
Q

What happens to the GI tract with SNS and PNS stimulation?

A 
SNS stim:
- decreased motility and secretion
- sphincter contraction
PNS stim:
- increased motility and secretion
- sphincter relaxation
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15
Q

What happens to the gallbladder and urinary bladder with SNS and PNS stimulation?

A

SNS stim:
- relaxation of gall bladder and smooth muscle of bladder
- urinary sphincter contracts
PNS stim:
- contraction of gall bladder and smooth muscle of bladder
- urinary sphincter relaxation

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16
Q

What is down regulation?

A

Extended exposure to agonists decreases the number of receptors, BUT not their response
- results in tachyphylaxis (rapidly decreased response to successive doses of a drug, rendering it less effective)

17
Q

What is up regulation?

A

Chronic depletion of catecholamines or use or antagonists increases the number of receptors, BUT not their sensitivity
- may account for withdrawal syndrome with ß-blockers

18
Q

There are 3 types of receptor desensitization: receptor uncoupling, sequestration, and down regulation. What is occurring in each?

A

RECEPTOR UNCOUPLING:

  • inability of receptor to bind G protein —> alters function of receptor
  • occurs rapidly (seconds to minutes)

SEQUESTRATION

  • movement of receptors from cell surface to intracellular compartments
  • occurs more slowly (minutes- hours)
  • still reversible

DOWN-REGULATION:

  • movement of receptors from cell surface to intracellular compartments, BUT then destroyed.
  • prolonged process (hours-days)
19
Q

What is pheochromocytoma?

A

Uncontrolled release of catecholamines d/t adrenal gland tumor
—> constant CNS stimulation

20
Q

What are catecholamines?

A

(Catechole structure and amine/protein)

  • both neurotransmitters and hormones
  • act on adrenergic receptors
  • dopamine, epinephrine, norepinephrine, isoproterenol, dobutamine
21
Q

What are sympathomimetics?

A
  • compounds that resemble catecholamines
    • missing certain structures
  • any drug that acts at SNS is considered a sympathomimetic
    • some act on SNS, but don’t resemble catecholamines
22
Q

What is an indirect sympathomimetic?

A

Ephedrine

  • synthetic non-catecholamine
  • releases endogenous norepinephrine from post ganglionic sympathetic nerve endings
23
Q

What is a direct- acting sympathomimetic?

A

(Phenylephrine)

  • catecholamines and synthetic catecholamines
  • activate adrenergic receptors directly
24
Q

_________________ is a pure alpha agonist, while _________________ is a pure ß-agonist.

A
  • phenylephrine

- isoproterenol

25
Q

What are the main things that cause autonomic dysfunction?

A 
Aging:
- orthostasis—> compensatory vasoconstriction fails
- temperature instability
- decreased stress response
- decrease pre-junctions terminals
Diabetes:
- diarrhea
- impotence
- gastroporesis
- hemodynamic instability —> hypotension
26
Q

What does the adrenal medulla do?

A

Release epinephrine (80%) and norepinephrine in response to Ach trigger at cholinergic fibers d/t Ca++ influx

Pharm 1 (9 decks)

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