Chemical Transmission in the Nervous System

Question 1

What are the major sites of pharmacological manipulation at synapses?

Answer 1

action potential propagation, NT synthesis, NT storage, NT metabolism, NT release, NT uptake, NT degradation, receptors

Question 2

Which fibre is longer in the sympathetic nervous system?

Answer 2

The post ganglionic fibre

Question 3

Which fibre is longer in the parasympathetic nervous system?

Answer 3

The pre ganglionic fibre

Question 4

How is acetylcholine synthesised?

Answer 4

A choline carrier takes choline into the neuron where it combines with Acetyl CoA (from mitochondria) by the enzyme choline-acetyltransferase to make acetylcholine. Acetylcholine is taken up into vesicles by acetylcholine carrier.

Question 5

How is noradrenaline synthesised?

Answer 5

Tyrosine is taken up into the neurone where it is converted to L-DOPA by tyrosine hydroxyls. L-DOPA is converted to dopamine by DOPA decarboxylase. Dopamine is taken up into vesicles where it is converted to noradrenaline by dopamine-beta-hydroxylase.

Question 6

How is adrenaline synthesised?

Answer 6

Noradrenaline is synthesised as before and then in the vesicle it is converted to adrenaline by phenylethanolamine-N-methyl transferase.

Question 7

How is acetylcholine inactivated?

Answer 7

It is broken down into choline in the synapse by acetylcholine esterase

Question 8

How is noradrenaline inactivated?

Answer 8

It is taken back up into the pre junctional cell by uptake 1 and taken up into the post junctional cell by uptake 2

Question 9

What is the neurotransmitter used by post ganglionic parasympathetic fibres?

Answer 9

Acetylcholine

Question 10

What is the neurotransmitter used by post ganglionic sympathetic fibres?

Answer 10

Noradrenaline - with the exception of at the sweat glands and the adrenals where acetylcholine is used

Question 11

What is the neurotransmitter used by all pre ganglionic fibres in the sympathetic and parasympathetic nervous systems?

Answer 11

Acetylcholine

Question 12

What are the receptors for acetylcholine?

Answer 12

Nicotinic receptors (ligand gated ion channels) and muscarinic receptors (GPCRs)

Question 13

What is the natural antagonist for muscarinic receptors?

Answer 13

atropine

Question 14

What is the natural antagonist for nicotinic receptors?

Answer 14

curare

Question 15

What are the receptors for noradrenaline?

Answer 15

alpha and beta adrenoceptors (GPCRs)

Question 16

Where are nicotinic receptors located?

Answer 16

At the ganglion for both sympathetic and parasympathetic pre ganglionic fibres and on skeletal muscle

Question 17

Where are muscarinic receptors?

Answer 17

At the organs/tissues for parasympathetic post ganglionic fibres

Question 18

Where are alpha/beta adrenoceptors?

Answer 18

At the organs/tissues for sympathetic post ganglionic fibres

Question 19

What is the clinical significance of receptor polymorphisms?

Answer 19

Different people will have different drug responses