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Membranes and Receptors > The Autonomic Nervous System and Drugs > Flashcards

The Autonomic Nervous System and Drugs Flashcards

1
Q

Where in the spine do parasympathetic fibres originate from?

A

Cranio-sacral

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2
Q

Are the pre-ganglionic fibres of the parasympathetic system long or short?

A

Long myelinated

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3
Q

Are the post ganglionic fibres of the parasympathetic system long or short

A

Short, unmyelinated

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4
Q

Where are the ganglia of parasympathetic fibres located?

A

In the tissues

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5
Q

What is the main neurotransmitter of the parasympathetic nervous system

A

ACh

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6
Q

How many ACh molecules need to bind to a nicotinic AChR in order for it to open

A

2

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7
Q

From what region of the spine to fibres of the sympathetic system originate from

A

Thoracolumbar

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8
Q

Are the preganglionic fibres of the sympathetic nervous system long or short

A

Short

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9
Q

Where are the sympathetic ganglia located

A

Paravertebral chain

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10
Q

Are the postganglionic fibres of the sympathetic system long or short

A

Long unmyelinated

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11
Q

What is the main neurotransmitter of the sympathetic nervous system

A

Noradrenaline

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12
Q

How is noradrenaline synthesised? What is the rate limiting step

A

Tyrosine–> L-DOPA –> Dopamine –> Noradrenaline (–> adrenaline)

Rate limiting step is the reaction of tyrosine –> L-DOPA by tyrosine hydroxylase
The final step occurs in the vesicles

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13
Q

Why is tyrosine considered an essential amino acid

A

As it is not one that we can make ourselves it has to come from the diet

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14
Q

What else is tyrosine important in the synthesis of

A

Thyroxine

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15
Q

What type of neurones can all pre-ganglionic neutrons be considered to be

A

Cholinergic

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16
Q

What is the difference between muscarinic and nicotinic ACh receptors

A 
Nicotinic = ligand gated
Muscarinic = GPCR
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17
Q

Where will you find post-ganglionic neutrons that are not adrenergic

A

Sweat glands and hair follicles

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18
Q

What is the name of the substances that can be co-released with NA or ACh and give an example of one

A

Non-adrenergic, non-cholinergic (NANC) transmitters

e.g. 5-HT (serotonin)

19
Q

Describe the sympathetic postganglionic neutrons at the adrenal glands

A

The neurones form chromatin cells which when stimulated by the release of ACh from the presynaptic neurone release adrenaline into the blood stream

20
Q

Describe the synthesis of ACh and where is occurs

A

Synthesised from choline and acetyl Co-A by the enzyme choline acetyltransferase (CAT)
In the cytoplasm of cholinergic terminals

21
Q

How is ACh broken down?

A

By acetylcholinesterase

to acetate and choline (which is largely recycled by reuptake through a choline transporter)

22
Q

Explain how acetylcholinesterase can be used as a drug target and give an example of one such drug

A

Inhibitors for acetylcholinesterase can be used to prevent the breakdown of ACh and therefore prolong the action at the postsynaptic membrane
This is useful in myasthenia gravis
e.g. pyridostigmine

23
Q

Name nicotinic cholireceptor antagonist that has action at the ganglion and give its action

A

Trimethapan ganglion-blocker which is used in hypertensive crisis during surgery

24
Q

Name a nicotinic AChR antagonist which has action at the neuromuscular junction

A

Tubocurarine –> muscle paralysis

25
Q

What is the action of pilocarpine and what receptors does it act on

A

Muscarinic AChR agonist used to treat glaucoma

26
Q

Name a muscarinic AChR antagonist and give its use

A

Ipratropium bromide and tiotropium used to treat asthma and COPD (prevent bronchoconstriction)

27
Q

What type of drug is donepezil and when is it used

A

Acetylcholinesterase inhibitor used in Alzheimer’s disease

28
Q

What is the enzyme that is packaged in the vesicle that converts dopamine to noradrenalin

A

Dopamine beta hydroxylase

29
Q

What is a noradrenergic varicosity

A

A specialised site for Ca2+ dependent NA release on a highly branched axonal network

30
Q

Explain what Uptake 1 and Uptake 2 are

A

Two pathways of termination of the action of NA (proteins)

Uptake 1 captures 90-95% of NA reuptake into the vesicle by Na+-dependent high affinity transporter

Uptake 2 takes up that NA not captured by Uptake 1, lower affinity, non-neuronal

31
Q

What can happen to NA in the pre-synaptic terminal that is not taken up into vesicles

A

Can be metabolism by 2 enzymes:
Monoamine oxidase (MAO)
Catechol-O-methyltransferase (COMT)

32
Q

What is the action of alpha-methyl tyrosine

A

Competitive inhibition of tyrosine hydroxylase (prevents NA formation in pheochromocytoma)

33
Q

What is the action of alpha-methyl-DOPA

A

‘False transmitter’ accumulates in vesicles with NA and preferentially binds to pre-synaptic alpha 2 adrenoreceptor so exploited for treatment of hypertension

34
Q

What is the action of CarbiDOPA

A

Inhibits the action of DOPA decarboxylase in the periphery

Used in Parkinsons

35
Q

What are indirectly acting sympathomimetic agents and what is there use

A

They are structurally related to NA therefore recognised and taken up into the adrenergic terminal by Uptake 1 and into the vesicle –> leak of NA from the vesicle
e.g. amphetamine

36
Q

What class of drugs are uptake 1 inhibitor

A

Tricyclic anti-depressants

37
Q

What is dobutamine and what are its actions

A

Selective beta 1 agoinst

Positive chronotropic and ionotropic effects in the heart

38
Q

What salbutamol an example of and what are its actions

A

Beta 2 agoinst

Bronchodilation

39
Q

What is ephedrine an example of and what are its actions

A

Selective alpha 1 agonist

Used as nasal decongestant

40
Q

Name a selective alpha 2 receptor agonist and give its action

A

Clonidine

Used as an anti-hypertensive

41
Q

Name an alpha antagonist and give its use

A

Phentolamine

Used for peripheral vasodilation to treat peripheral vascular disease

42
Q

Name a selective alpha 1 antagonist and give its use

A

Prazosin

Used to treat hypertension

43
Q

Name a beta blocker and give its use

A

Propranolol
Used to treat hypertension, MI, angina
Contraindicated in asthmatics as can cause bronchoconstriciton

Membranes and Receptors (2 decks)

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