Autonomic Nervous System ( 2)

Question 1

What is the equation for the formation of ACH?

Answer 1

Acetyl coA+ choline = acetylcholine + coenzyme A

Question 2

How is ACH broken down ?.

Answer 2

ACH = acetate + choline by acetylcholine esterase

Question 3

What is an example of a ganglion blocking drug?

Answer 3

Trimethaphan which is a nicotinicantagonist

• it is used to treat hypertension.

BUT IT IS NOT USED A LOT NOWADAYS.

Question 4

How can we treat myasthenia gravis ?

Answer 4

• ACH esterase inhibitors gets pyridostigmine which inhibits ACH esterase which allows ACH concentration to increase in the synaptic cleft - this makes it more likely for ACH to bind to receptors.

Question 5

Tolterodine

Answer 5

Muscarinic antagonist which is used to treat an overactive bladder

Question 6

A relative lack of selectively of drugs means that there are often unwanted side effects.

• for example non-selective muscarinic ACH receptor agonist is likely to cause autonomic side effects such as …..

Answer 6

• heart rate decreases
• cardiac output decreases
• bronchoconstriction increases
• GI tract peristalsis increases
• sweating and salvation increases

Question 7

What does the SLUDGE mnemonic for ?

Answer 7

Describes the pathological effects on the the parasympathetic nervous system which is usually due to over stimulation of the muscarinic ACH receptors: this is CAUSED

1) overdosed on drugs
2) magic mushrooms consumption
3) organophosphorus poisoning ( sarin or parathion)

Question 8

SLUDGE mnemonic

Answer 8

S - salivation : stimulation of the salivary glands

LACRIMATION: stimulation of lacrimal gland

URINATION : relaxation of the urethral internal sphincter muscle and detrusor muscle contraction

DEFECATION ( discharge of faeces )

Gastrointestinal upset : diarrhoea

EMESIS: vomiting

Question 9

What may sludge be treated with ?

Answer 9

• atropine or any other anti-cholingeric agents

Question 10

Tolterodine , darifenacin , oxybutynin

Answer 10

Used to treat an overactive bladder

• they are muscarinic ACH antagonists

Question 11

Ipratropium triotropium

Answer 11

Used to treat some forms of asthma and COPD

• it is a muscarinic ACH antagonist

Question 12

Pilocarpine and bethanechol

Answer 12

Muscarinic ACH receptor agonists

• used to treat glaucoma and stimulate bladder emptying

Question 13

What is a varicosities

Answer 13

Specialised site for ca2+ dependent noradrenaline release

Question 14

How is noradrenaline synthesised ?

Answer 14

1) begins with tyrosine
2) tyrosine is hydroxylated by tyrosine hydroxylase which forms DOPA
3) DOPA is then decarboxylated by DOPA decarboxylase which forms DOPAMINE.
4) ALL THR ABOVE OCCURS IN THE CYTOSOL
5) dopamine is then hydroxylated by dopamine -B -hydroxylase which forms noradrenaline ( THIS OCCURS IN THE VESICLE).

Question 15

Does noradrenaline have limited or extended time when it comes to influencing post synapticadrenoceptors?

Answer 15

Limited time as it is rapidly removed from the synaptic cleft by noradrenaline transporter proteins

Question 16

How is noradrenaline taken up to the pre-synaptic terminal ?

Answer 16

• taken up by Na+ dependant , high affinity transporter

- this is called ‘ uptake 1’

Question 17

What happens if noradrenaline is not recaptured by uptake 1?

Answer 17

It is then taken up by a lower affinity, non neuronal mechanism

Question 18

What occurs during the pre- synaptic terminal when nor adrenaline is taken up?

Answer 18

• if it is not taken up by vesicles , it is susceptible to metabolism by 2 enzymes
  1) monoamine oxidase
  2) catechol-O-methyltransferase

Question 19

Why do we need to use selective agonists/antagonists ?

Answer 19

To prevent side effects

Question 20

What is an example of a selective agonist that works to reverse bronchoconstriction?

Answer 20

• salbutamol which works on b2-adrenoreceptors by causing the smooth muscle to relax causing the airways to widen.
• this is selective because it is important to limit possible cardiovascular side effects.