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Medneuro- M2-2- NT systems > ANS pharmacology - Rex > Flashcards

ANS pharmacology - Rex Flashcards

1
Q

which statement is correct?
a. the sympathetic system is the FIGHT or FLIGHT system and its main NT is noradrenaline, whereas the parasympathetic system is the CALMING DOWN system and its main NT is ACh

b. a. the parasympathetic system is the FIGHT or FLIGHT system and its main NT is noradrenaline, whereas the sympathetic system is the CALMING DOWN system and its main NT is ACh

A

a

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2
Q

routes of the sympathetic and parasympathetic neurons

A

sympathetic: symp. nerves leave the T1-L3 region of the spinal cord–> synapse in para-or prevertebral ganglia & plexus of abdomen cavity–> postganglionic, nonmyelinated fibres arise from neurons –> all organs

Parasympathetic: preganglionic fibres leave CNS via cranial nerves and 3&4 sacral spinal roots–> travel much further than sympathetic fibres before synapsing in ganglia (sometimes ganglion is the target)–> postgang. parasympathetic fibres release ACh

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3
Q

which of the following statements is/are correct?
a. preganglionic fibres belong to the parasympathetic NS because they release ACh from their terminals

b. preganglionic fibres can be a part of both sympathetic and parasympathetic system and release ACh
c. preganglionic fibres are all myelinated
d. preganglionic fibres are unmyelinated fibres of the sympathetic NS
e. ACh from preganglionic fibres depolarises ganglion neurons by activating nAChR

A

b, c, e

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4
Q

what is the difference between the sympathetic and parasympathetic systems UNTIL the ganglion?

A

the place of origin; NT is the same (ACh)

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5
Q

what is the problem with drugs that block ACh-esterase?

A

these drugs increase ACh levels in the synaptic cleft; this leads to intoxication, and elicits reactions of BOTH systems (sympathetic and parasympathetic);

  • sympathetic activation- increased heart rate and BP, tachycardia…
  • parasympathetic activation- salivation…
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6
Q

which of the following statements about the ANS is/are correct?

a. all ANS neurons release NT (either ACh or NE)
b. some ANS neurones release neither ACh nor NE
c. adrenaline is a sympathomimetic agent
d. alpha1 receptors are the most common noradrenalin receptors
e. alpha2 receptors are more common than alpha1

A

b, c, e

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7
Q

which neurons release ACh?

A
  • ALL preganglionic autonomic fibres
  • postganglionic parasympathetic nerves
  • SOME postgang. sympathetic nerves (for thermoregulation, sweat glands and skeletal muscle vasodilator fibres)
  • nerve of the adrenal mdulla
  • somatic motor nerves to skeletal muscle endplates (NMJ)
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8
Q

which of the following statements about ACh is/are correct?

a. ACh released from nerve terminals of postganglionic parasympathetic fibres act on muscarinic ACh receptors (mAChR)
b. ACh released from nerve terminals of postganglionic parasympathetic fibres act on nicotinic ACh receptors (nAChR)
c. ACh released from postganglionic parasympathetic fibres can be blocked by atropine
d. ACh effect is usually excitatory except for the heart, which receives inhibitory cholinergic fibres from the vagus
e. ACh effect is always inhibitory

A

a, c, d

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9
Q

what are the 2 classes of cholinomimetic drugs?

A
  1. direct nicotinic or muscarinic agonists- act directly on receptors; only few uses (e.g. pilocarpine)
  2. anti-cholinoesterases- drugs which inhibit AChE and act indirectly by allowing ACh to accumulate in the synaptic cleft; used mainly for nicotinic effects on the NMJ (e.g. myasthenia graves treatment)
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10
Q

what are the parasympathetic effector organs most sensitive to muscarinic antagonists?

A

secretion of salivary, bronchial and sweat glands

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11
Q

inactivation of norepinephrine and epinephrine…

a. enzymatic degradation by the enzyme norepinephrine-decarboxylase (NEDC) and epinephrine decarboxylase (EDC)
b. diffusion
c. reuptake
d. all of the above

A

c

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12
Q

sympathomimetic amines (which one is WRONG)…

a. increase release of NE
b. are selective for NE
c. similar effect to epinephrine but last much longer
d. amphetamines have low abuse potential
e. have a positive effect on mood and depressive effect on appetite

A

d

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13
Q

medical uses of adrenoreceptor-antagonists

A
  • ß-blockers- treatment of hypertension, angina, cardiac arrhythmia, heart failure and glaucoma
  • alpha-blockers- little clinical use; parzosin (selective alpha1 antag.) used to treat hypertension
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14
Q

can you elaborate on the presynaptic modulation in the ANS

A

NTs of the sympathetic system have an inhibitory effect on ACh release from the parasympathetic NS –> release of NE and epinephrine further reduce release of ACh (negative feedback loop)

  • NE and ACh synapses are often close together in order to regulate the ANS activity (as sympathetic and parasympathetic systems work together)
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15
Q

what are the advantages of co-transmission in the ANS?

A
  • one component of the actors may be inactivated more slowly than the other and thus produce longer lasting effects.
  • balance of transmitter release may vary under different conditions, so differential release of one or another mediator may result from different impulse patterns
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16
Q

give one example for each of the following drug types:

  • direct parasympathomimetic drugs
  • indirect parasympathomimetics (anti-cholinoesterases)
  • muscarinic antagonist
A
  • direct: pilocarpine - eyedrops, used to reduce intraocular pressure; does not have an ester group so AChE ineffective
  • indirect: physiostigmine - decrease cardiac function, increases gut activity, used in CNS intoxication and glaucoma
  • mus. antagonists: Atropine - pronounced effect on cardiac and gut function.
17
Q

can you name the 3 types of drugs acting on the NMJ?

A
  1. agents that reduce ACh release - decrease Ca2+ influx–> reduce ACh exocytosis from presynapse
  2. agents that potentiate transmission- act on AChE, reducing its activity (more ACh in the cleft)
  3. NMJ blockers- competitive (e.g. pancurionium) or depolarising (e.g. suxamethonium)
18
Q

describe the IDEAL relaxant

A
  • non depolarising
  • rapid onset
  • dose dependent duration
  • no side effect
  • elimination independent of organ
  • no active or toxic metabolites
19
Q

what are the major subtypes of adrenoceptors?

A
  1. Alpha (1 &2)
  2. Beta (ß1, 2,3)
  • -> subtypes can be distinguished pharmacologically
  • -> different receptors are differently distributed according to tissue region
20
Q

alpha-adrenomimetic drugs…(which answer is WRONG?)

a. are used for nasal congestion and glaucoma
b. are non selective and thus have many side effects
c. include adrenaline
d. activate phospholipase C
e. are used to treat hypertentsion

A

b. are non selective and thus have many side effects

21
Q

how do MAOIs affect the noradrenergic synapse?

A

MAOI block monoamine-oxidase, so NA is not degraded in the presynaptic cell

22
Q

What effects would you expect when applying reserpine to a patient?

A
  • reserpine blocks the uptake of NA by vesicles (blocks VMAT transporters).
  • decreased blood pressure
  • tiredness
23
Q

what is the action of alpha-adrenoceptors?

A
  • contraction of the arterioles and veins –> raise BP (alpha1)
  • contraction of the radial miscalls of the iris (reduce tear production)
  • GI relaxation
  • bladder trigone contraction
  • uterus contraction
  • splenic capsule contraction
  • inhibit insulin secretion (mostly alpha2)
  • ejaculation of male sex organs
  • K+ and water secretion of salivary glands (alpha1)
24
Q

what is the action of beta adrenoceptors?

A
  • dilation of arterioles and veins –> decrease BP (ß2)
  • cardiac stimulation –> increase heart rate
  • bronchodialation (ß2)
  • enhanced tear secretion (eyes)
  • GI relaxation (ß2)
  • NMJ transmission - tremor (ß2)
  • augmented insulin and glucagon secretion (ß2)
  • liver glycogenesis (ß2)
  • lipolysis (degeneration of fats) (ß2)
  • renin release - kidney (ß1)
  • ADH secretion (pituitary) -ß1
25
Q

what drug would you prescribe to an asthmatic patient?

A
  1. ß2 agonists cause bronchodialation in the bronchiolar smooth muscle
  2. anticholinergic drugs- e.g. atropine, block cholinergic constrictor tone and act primarily on large airways

Medneuro- M2-2- NT systems (11 decks)

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