The Sympathetic Nervous System I and II Flashcards Preview

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Flashcards in The Sympathetic Nervous System I and II Deck (28)
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1
Q

What are post ganglionic sympathetic neurotransmitters?

A

noradrenaline, with ATP as a secondary transmitter. Co-transmitters can be NPY

2
Q

What is so special about sweat glands?

A

They release ACh post synaptically which acts on mAChRs.

3
Q

What G proteins are a-receptors coupled to and explain their mechanism

A

a1 receptors are coupled to Gq receptors. This is coupled with phospholipase C. When activated, PLC will cleave pip into DAG and IP3. IP3 will bind and release Ca2+, and this Ca2+ will work with DAG to activate PKC. PKC activation causes phosphorylation of the target protein.

a2 receptors are coupled with Gi proteins. This is an AC inhibitor on the pre-synpatic nerve terminal.

4
Q

What G proteins are B receptors coupled to and explain their mechanism.

A

Gs proteins - this is coupled with adenylate cyclase, which converts ATP into cAMP. cAMP will cause influx of Ca2+ and heart muscle contraction.

5
Q

Which B adrenoceptors are non-innervated?

A

B2 are non innervated and must rely on circulating adrenaline.

6
Q

What metabolic effects of skeletal muscle do B2 receptors mediate?

A

The conversion of glycogen into lactic acid, causing hyperlactic acidemia.

7
Q

What effect does a1 adrenoceptors have on the liver?

A

It will cause the release of K+, which leads to hyperkalaemia.

8
Q

What effect does a2 adrenoceptors have on insulin release

A

Activation of a2 adrenoceptors cause inhibition of insulin release.

9
Q

What is adrenaline reversal?

A

Adrenaline reversal occurs during the administration of a1 antagonists. When the a1 receptor is antagonised, the adrenaline will reveal effects on the B2 receptor, which is vasodilation and hence a fall in blood pressure.

10
Q

What is a adrenoceptor agonist used as a nasal decongestant?

A

phenylphrine

11
Q

What is a a-adrenoceptor antihypertensive?

A

clonidine

12
Q

What kind of drug is dipivefrine and what can it be used for? How does it work?

A

dipivefrine is used for simple open glaucoma >21 mmHg intraocular pressure. This is a prodrug. The esterification of adrenaline with pivalic acid will allow this drug to cross the cornea easily.

As a result, it will reduce the rate of production of aqueous humor by a2 activation and causing vasoconstriction of afferent arterioles in ciliary body. It also facilitates absorption of aqueous humor by activating a2 adrenoceptos on veins that drain the canal of schlemm.

13
Q

Why is dipivefrine contra-indicated in closed angle glaucoma?

A

Because the increase in pupillary size (mydriatic action) ill just worsen the angle.

14
Q

What can dobutamine be used for?

A

cardiogenic chock for cardiopulmonary resuscitation because it is a b1 agonist

15
Q

What are some side effects of salbutamol?

A

skeletal muscle tremors, hypokalemia

16
Q

What receptor agonists can be used in treatment of premature labour?

A

B2 to allow relaxation of uterine smooth muscle

17
Q

What are examples of indirect acting sympathomimetics?

A

Tyramine, Cocaine, Ephedrine, AMPHETAMINE

18
Q

What type of drug is phentolamine

A

Short acting reversible competitive alpha antagonist that is nonselective

19
Q

What type of drug is phenoxybenzamine?

A

Irreversible non competitive alpha antagonist that is non selective and non surmountable

20
Q

One use of Ergometrine

A

Postpartum haemorrhage

21
Q

One use of ergotamine

A

Migraine in acute attack

22
Q

One possible Ergot Alkaloid treatment for dementia

A

Hydergine

23
Q

Which B adrenoceptor antagonist shows local anaesthetic action?

A

Sotalol

24
Q

Which Beta blocker is used to treat aqueous humor production?

A

Timolol

25
Q

What can be an alternative option to surgery in the treatment of phaeochromocytoma?

A

a-methyltyrosine. This inhibits the tyrosine hydroxilase enzyme, causing block in the conversion of L tyrosine to L dopa. NA cannot be formed.

26
Q

What is the difference between MAO and COMT?

A

MAO and COMT both metabolize catecholamines, however COMT is specfic to catecholamines and MAO can metabolize other amines as well.

27
Q

Describe the Cheese Reaction

A

MAO usually metabolizes tyramine, which is present in foods made by bacteria in the intestinal epithelium. In the presence of MAO inhibition, the tyramine will enter via uptake 1 and displace NA. This evokes vasoconstriction at post junctional a adrenoceptors causing lethal hypertension. The likelihood of this phenomenon is reduced if mpatient is on a specific MAO-B inhibitor.

28
Q

What is the NA metabolite found in urine?

A

VMA. This is a good indicator of phaeocytochroma.