ANS Flashcards

1
Q

Which neurotransmitter is released at the parasympathetic first synapse?

A

Acetylcholine

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2
Q

Which type of receptor accepts the neurotransmitter at the parasympathetic first synapse?

A

Nicotinic ACh

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3
Q

Which neurotransmitter is released at the parasympathetic second synapse?

A

Acetylcholine

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4
Q

Which type of receptor accepts the neurotransmitter at the parasympathetic second synapse?

A

Muscarinic ACh

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5
Q

Which neurotransmitter is released at the sympathetic first synapse?

A

Acetylcholine

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6
Q

Which type of receptor accepts the neurotransmitter at the sympathetic first synapse?

A

Nicotinic ACh

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7
Q

Which neurotransmitter is released at the sympathetic second synapse?

A

Noradrenaline

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8
Q

Which type of receptor accepts the neurotransmitter at the sympathetic second synapse?

A

Alpha & beta adrenoreceptors

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9
Q

Which axon is longest in the parasympathetic nervous system?

A

Presynaptic (synapses near target organ)

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10
Q

Which axon is longest in the sympathetic nervous system?

A

Postsynaptic (synapses in sympathetic trunk = runs next to spinal cord)

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11
Q

Name two target organs purely innervated by only Sympathetic or the parasympathetic nervous system

A

Sweat glands

Blood vessels

(SYMPATHETIC)

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12
Q

Name 3 organs innervated by both the sympathetic and parasympathetic nervous system but the parasympathetic innervation predominates

A

GIT

Bladder

Salivary glands

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13
Q

What is the effect of the parasympathetics on the heart?

A

Slows

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14
Q

What is the effect of the sympathetics on the heart?

A

Fast

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15
Q

Name an organ in which the parasympathetics and sympathetics work together

A

Salivary glands

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16
Q

What are the 3 different types of G proteins?

A

q

s

i

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17
Q

What is a varicosity?

A

Sites where synapses occur along an axon = bulges out

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18
Q

1 in how many presynaptic action potentials cause a release?

A

50

19
Q

Which types of receptors are located at ganglionic synapses?

A

Inotrophic (ligand gated ion channels = acivated by 2 ACh = conformational change)

20
Q

What type of receptors are found at post ganglionic synapses?

A

Metabotrophic (GPCR) = changes what goes on inside cell

21
Q

What is the action of displacing agents?

A

They displace the NA from the synapse (displaces it from the varicosity)

  • competes with NA for uptake 1 (decrease reuptake of NA)
  • competes with NA for vesicular transporters
  • more NA in varicosity (reverse uptake 1 = Na & NA move out)
22
Q

What is pephedrine used for?

A

= displacing agent

  • reverse hypotension after epidural anaesthesia
  • decongestant nasal drops (vasoconstriction of mucosal blood vessels)
23
Q

What is pseudoephedrine used for?

A

Systemic nasal decongestant (in sprays, sudafed, lemsip & claritin D)

= displacing agent

n.b. some sudafeds and lemsips contain phenylephrine instead

24
Q

What is the action of amfetamine, metamfetamine & ecstacy at the CNS?

A

Cause severe hypotension

25
Q

What foods is tyramine found in?

A

mature cheese

pickled herring

broad bean pods

marmite

26
Q

What does tyramine cause?

A

High blood pressure

Sweating

27
Q

What happens when you give a person already taking a drug to increase snaptic [NA] a displacing agent too?

A

Hypertensive crysis

= hypertension, tachycardia (/reflex bradycardia)

28
Q

In which situations is methyldopa the preferred anti-hyertensive?

A

When other treatments have failed

In pregnancy

29
Q

What are the 2 different methods of action for methylopa as an anti-hypertensive?

A

Alpha 2 adrenoreceptor agonist

  1. inhbits NA exocytosis (also competes with NA & enters variosity through uptake 1 -> into vesicles => methyldopamine => methylNA
  2. reduces sympathetic drive to CNS -> crosses BBB = inhibits/reduces firing of SNS = decreased [NA] at synapses
30
Q

What does guanethidine do?

A

Noradrenergic neurone blocking drug

= rapid control of blood pressure in hypertensive emergency (depletes nerve endings of NA = no longer work)

VERY SEVERE SIDE EFFECTS

31
Q

SYMPATHETICS

Which receptors are the most prevalent in the heart?

A

Beta 1 adrenoreceptors

(sympathetics)

32
Q

SYMPATHETICS

What is the effect of the SNS on the heart?

A

Increased rate and contractility

33
Q

SYMPATHETICS

Which receptors are involved in constant sympathetic tone of the blood vessels?

A

Alpha 1 adrenoreceptors

34
Q

SYMPATHETICS

Why are beta 2 receptors in blood vessels not activated by NA from nerves?

A

They are extrasynaptic

35
Q

SYMPATHETICS

Which type of adrenoreceptors does circulating adrenaline (e.g. from stress) have a greater effect on?

A

Beta

(n.b. effect it concentration dependant)

36
Q

SYMPATHETICS

With a low circulating adrenaline level which receptors are activated?

And what is their effect?

A

Beta 2

Vasodilation

(activates adenyl cyclase = increase cAMP = inhibits myosin light chaine kinase = less contraction)

37
Q

SYMPATHETICS

With a high circulating adrenaline level which receptors are activated?

And what is their effect?

A

Alpha 1

Vasoconstriction

= activates phospholipase C = IP3 = increased intracellular Ca = contraction

38
Q

SYMPATHETICS

What are the main type of receptor in the lungs?

A

Beta 2 adrenoreceptors

39
Q

SYMPATHETICS

What are the lungs beta 2 adrenoreceptors activated by?

A

Circulating adrenaline or beta 2 agonists

40
Q

SYMPATHETICS

When the lungs beta adrenoreceptors are activated what happens to the lungs?

A

Brochodilation

41
Q

PARASYMPATHETICS

What happens when muscarinic receptors are stimulated?

A
  • Exocrine secretions = increased in salivary glands, GI tract, lacrimal & sweat glands
  • Smooth muscle = mainly contract (excluding blood vessels)
  • Heart = mostly inhibitory (hyperpolarisation via Gi)
  • ACh release from parasympathetic varicosities (inhibits Ca channels)
  • Vasodilation (NO from endothelial cells)
42
Q

What are the side effects of inhibition of muscarinic receptors?

A
  • Restlessness
  • Agitation
  • Disorientation (atropine)
  • Sedation
  • Amnesia (hyoscine)
43
Q

Which famous plant causes atrophine poisoning?

A

Deadly nightshade

44
Q

Why dont we use drugs for nACh receptors?

A

We wouldn’t be able to selectively activate SNS/PNS = mix of effects and would trigger autonomic reflexes