Introduction. Flashcards
What is the cholinergic nervous system?
The part of the parasympathetic nervous system uses ACH as the neurotransmitter at the pre-ganglion and at the effector cell.
What is the main neurotransmitter of the cholinergic nervous system?
Acetylcholine.
Where are neurotransmitters synthesised and stored?
In the pre-synaptic neuron.
What are the major pre-cursors for acetylcholine formation?
Choline and acetyl co-enzyme A.
What molecule is acetyl co-A derived from?
Pyruvate.
Where is acetyl Co-A synthesised?
In the mitchondria of the terminal end of the pre-synaptic neuron.
Where does the choline that is used to synthesise ACH come from?
It is bought in from the extracellular fluid.
What enzyme binds the choline group to the acetyl group during ACH formation?
Acetyl transferase.
What part of the pre-synaptic neuron does acetyl transferase lead to the binding of acetyl and choline?
In the cytoplasm.
When will ACH be released by the pre-synaptic neuron/
Following an action potential.
What receptors will ACH bind to on the post synaptic neuron?
Muscarinic or nicotinic receptors.
What enzyme breaks down ACH in the synaptic ganglion?
Acetylcholine esterase.
What drug inhibits choline transport?
Hemicholinium.
What drug inhibits ACH transport to the membranes of the pre-synaptic vesicle?
Vesamicol.
What toxins will affect the release of ACH from the pre-synaptic neuron?
Botulinum.
Black widow toxin.
What does acetylcholine break acetylcholine into?
Acetate and choline.
What happens to the choline that is formed form the breakdown of ACH in the synaptic cleft?
It is recycled.
Where is acetylcholine esterase synthesised?
In the autonomic ganglia.
In the neuromuscular motor endplates.
In the visceral neuroeffector junctions.
What is the function of butyryl cholinesterase?
It breaks down choline esters that come form an exogenous source e.g. in food.
What happens if acetylcholine esterase is inhibited?
Acetylcholine will build up in the synaptic cleft.
What effects are generated when ACH binds to a nicotinic receptor?
Nicotinic effects.
What effects are generated when ACH binds to a muscarinic receptor?
Muscarinic effects.
What kind of receptors are nicotinic receptors?
Ligand gated ion channels.
Where are nicotinic receptors mainly found in the body?
At the neuromuscular junction of skeletal muscle.
What are the 2 subtypes of nicotinic receptors?
Nicotinic muscular receptors.
Nicotinic neuronal receptors.
Where are nicotinic muscular receptors found?
In the neuromuscular junction.
What effects will depolarisation of neuromuscular junctions lead to?
Contraction of skeletal muscle.
Where are nicotinic neuronal receptors found?
In the autonomic ganglion.
In the CNS.
In the adrenal medulla.
Muscarinic receptors are what kind of receptors?
GCPR’s.
What kind of responses can be released by muscarinic receptors?
Excitatory and inhibitory responses.
What kind of responses can be released by nicotinic receptors?
Only excitatory responses.
Where nicotinic receptors located?
On the postsynaptic membrane of parasympathetic neurons.
On the vascular endothelium.
On the pre-synaptic nerve terminals.
In the CNS.
When will nicotinic receptors in the vascular endothelium be activated?
When the ACH is released into the blood.
Where are non-innervated muscarinic receptors located?
In the vascular endothelium.
What happens when the nicotinic receptors in the neuroeffector junction of the sympathetic nervous system have?
They decrease the cardiac responses to sympathetic nerve activity.
What are the 5 subtypes of muscarinic receptors?
M1.
M2.
M3.
M4.
M5.
Where are M1 muscarinic receptors found?
On the ganglia and in secretory glands.
Where are M2 muscarinic receptors found?
In the myocardium and in smooth muscle.
Where are M3 and M4 muscarinic receptors found?
In smooth muscle and in secretory glands.
Where are M5 muscarinic receptors found?
In the CNS only.
What kind of muscarinic receptors are found in the CNS?
All 5 subtypes.
What protein is attached to the M1, M3 and M5 muscarinic receptors?
GQ protein.
What protein is attached to the M2 and M4 muscarinic receptors?
GI protein which inhibits adenylyl cyclase and activates receptor operated potassium channels.
What effects will M2 receptors have on the body?
They decrease impulse conduction in the SA and AV node and this leads to decrease in heart rate.
What effects will M3 receptors have on the body?
Smooth muscle contraction and increased secretion of secretory glands.
What happens when non-innervated M3 receptors in the vascular endothelium are activated?
Release of nitric oxide and vasodilation.
What are the effects of cholinergic agonists?
They produce acetylcholine like effects on the effector cell.
What are parasympathomimetic agents?
Drugs that are cholinergic agonists.
What effect will indirect acting choline esters have?
They cause acetylcholine to build up in the synaptic junction.
How will indirect acting choline esters cause acetylcholine to build up in the synaptic junction?
By inhibiting acetylcholine esterase.
What are the effects of increasing acetylcholine build up in the synaptic junction?
Increased cholinergic effects.
What are the 2 classes of direct acting parasympathomimetics?
Choline esters.
Natural alkaloids.
What are the 2 types of choline esters that are direct acting parasympathomimetic agents?
Carbachol.
Bethanechol.
What is the types of natural alkaloid that is a direct acting parasympathomimetic agents?
Pilocarpine.
What are the 2 types of pilocarpine?
Arecoline.
Muscarine.
What are the 2 classes of cholinesterase inhibitors?
Reversible.
Irreversible.
What are the 4 classes of reversible cholinesterase inhibitors?
Physostigmine.
Neostigmine.
Edrophonium.
Pyridostigmine.
What is the main class of irreversible cholinesterase inhibitors?
Organophosphates.
What effects will indirect cholinergic agonists have?
They inhibit acetylcholine esterase.
