MODULE B

Question 1

Compare Sympathetic and Parasympathetic systems

Answer 1

Sympathetic:

• preganglionic fibres leave via thoracic and lumbar nerves
• fight or flight, widespread results
• short pre- fibres, long post- fibres
• ACh at ganglionic synapse, Norep at neuroeffector site
• Norep and Norep-like drugs affect adrenergic receptors
• bronchodilate, cardiac stimulation

Parasympathetic:

• fibres leave via sacral and cranial nerves
• rest and digest, targeted refined effects
• long pre-fibres, short post-
• ACh at ganglionic synapse and neuroeffector site
• bronchoconstriction, cardiac inhibition

Question 2

How does Botulinum Toxin work?

Answer 2

blocks exocytotic release of acetylcholine and inhibits neuromuscular transmission

Question 3

Describe Acetylcholine Inactivation

Answer 3

by hydrolysis by two enzymes: acetylcholinesterase (inactivates only ACh, found in neuroeffector synapse) and pseudocholinesterase (inactivates choline esters or drugs like ACh, found in blood)

Question 4

Purpose of ACh autorecptors on presynaptic neuron

Answer 4

negative feedback receptors; any excess ACh in synapse that binds to these receptors inhibits release of more ACh

Question 5

receptors that respond to ACh or ACh-like drugs

Answer 5

cholinergic receptors

Question 6

two types of cholinergics

Answer 6

muscarinic (M1-5) and nicotinic (mN, nN)

Question 7

where muscarinic receptors are found

Answer 7

in smooth muscle, cardiac tissue, glands

Question 8

type of receptor muscarinic

Answer 8

G protein-coupled receptors

Question 9

M2 Receptors

Answer 9

(cardiac) located on cardiac muscle cells, stimulates a slowing of the heart (bradycardia)

Question 10

M3 Receptors

Answer 10

(glandular) located on bronchial smooth muscle, exocrine glands and on pulmonary and bronchial vascular smooth muscle, stimulates bronchoconstriction, ^ mucus secretion and vasodilation

Question 11

type of receptor nicotinic

Answer 11

ligand-gated Na+ channels = sodium influx and membrane depolarization

Question 12

nN Receptors

Answer 12

(neuronal, ganglionic) located at all pre-synaptic or autonomic ganglia
stimulation = excitement of postganglionic fibres and release of neurotransmitters at sympathetic and parasympathetic neuroeffector site

Question 13

mN Receptors

Answer 13

(muscle) , located in skeletal muscle, results in skeletal muscle contraction
- ACh-gated sodium channel

Question 14

direct-acting cholinergics

Answer 14

similar in chemical shape to ACh or natural plant alkaloids

• directly attach to receptor and stimulate it
• not site specific, resulting in overlapping effects
• inactivated by cholinersterase enzyme

Question 15

examples of direct-acting cholinergics

Answer 15

pilocarpine, provocholine (methacholine) and champ (verenicline)

Question 16

clinical effects of direct-acting cholinergics

Answer 16

constrict pupils, ^ mucus, decrease HR, contraction of bronchial smooth muscle

Question 17

two forms of indirect-acting cholinergics

Answer 17

reversible and quasireversible

Question 18

use of reversible cholinesterase inhibitors

Answer 18

• reverse neuromuscular blockade caused by non-depolarizing neuromuscular blockers (cuarariform drugs)
• Dx and Tx when lack of ACh is problem
• Tx glaucoma

Question 19

examples of indirect acting cholinergics

Answer 19

tension (edrophonium), prostigmin (neostigmine), mestinon (pyridostimine)