Neurotransmitters Flashcards
Neurotransmitters are —— chemicals
Endogenous
Neurotransmitter classification:
What class for dopamine, noradrenaline, adrenaline, serotonin?
Monoamines
What are the catecholamines?
- dopamine
- noradrenaline
- adrenaline
Neurotransmitter nomenclature: neurones suffix
Ergic
Cholinergic etc
Neurotransmitter Nomenclature: Receptors:
- cholinergic receptors
- dopaminergic receptors
- adrenoreceptors
Noradrenaline and adrenaline are most important in the —— nervous system
Sympathetic: cardiac contraction, release of glucose,
Dopamine, noradrenaline and adrenaline share the same synthesis pathway.
True or false?
True
Dopamine, noradrenaline and adrenaline come from amino acid tyrosine.
True or False?
True
What is the order of synthesis of dopamine, noradrenaline and adrenaline? Why does synthesis stop?
- Tyrosine
- dopa
- dopamine
- noradrenaline
- adrenaline
- synthesis stops depending on the enzymes present in the neurone
Noradrenaline is released by ——— nerve terminals.
Adrenaline is secreted by ———— cells in the ——— ———.
- sympathetic
- chromaffin cells
- adrenal medulla
Agonists of alpha adrenoreceptors in order of affinity (highest to lowest):
Noradrenaline
Adrenaline
Isoprenaline
Antagonists of alpha adrenoreceptors
Phentolamine
Agonists of beta adrenoreceptors in order of affinity
Isoprenaline
Adrenaline
Noradrenaline
Antagonists of beta adrenoreceptors:
Propranolol
Beta adrenoreceptors are sensitive to up/down regulation.
True or False?
True
Regulating expression or numbers of receptors
Alpha 1 adrenoreceptors are mainly post synaptic.
True or False?
True
Alpha 2 adrenoreceptors are mainly pre-synaptic.
True or False?
False
Both post or pre synaptic
Function of alpha 2 adrenoreceptors on pre-synaptic membrane.
- Control release of noradrenaline
- mechanism of negative feedback
- NA released in synaptic cleft and acts upon post synaptic receptors
- when NA binds to the pre-synaptic receptors, stops the release of NA from pre-synaptic neurone
Fill in the table.
Pre-synaptic receptors are generally
Involved in feedback mechanisms for example alpha 2 adrenoreceptors
Fill in the table.
Signal Termination: Adrenergenic transmission in ANS
- main mechanisms vis plasma membrane noradrenaline transporter (NAT or NET)
- transporter in membrane of pre-synaptic neurone
- limits action and recycles as re-packaged in vesicles
Minority uptake by non neuronal cells:
- metabolism of endogenous and exogenous NA and Adr
- Monoamine oxidases MAO
- Catech-O-methyl transferase COMT
Antidepressants and cocaine inhibit
NAT
Other monamine transporters
Propranolol stops signs of external anxiety.
True or False?
True
Peripheral nervousness
Hand tremors
Too much propranolol causes
Tolerance
Beta receptors upregulated so more agonists can bind
Fill in the table.
Fill in the table.
Ach receptors.
Location of Ach receptors and effect of activation.
Signal termination of acetylcholine
Metabolism by acetylcholinesterase (AChE) and butyrylcholinesterase BuChe
The autonomic system regulates
Branches of the nervous system that regulates involuntary functions
Complete diagram.
Parasympathetic and how to remember.
- parasympathetic, long, at eases so in the end muscarinic receptors
Complete diagram.
Sympathetic and how to remember.
ANS - parasympathetic:
- preganglionic neurones
- cell bodies in the grey matter of the brain stem or lateral horn of spinal chord grey matter from S2-S4
- long, synapse with postganglionic neurones at or near organ
- release Ach to activate nicotine receptors on postganglionic neurones
ANS - Parasympathetic:
Postganglionic neurones
- cell bodies are in indistinct ganglia near or on their final target organ (further away from the spinal chord)
— short, synapse on the target organ
- releases Ach to activate muscarinic receptors on the target organ
ANS - Sympathetic:
Pre-ganglion if
- cell bodies are in the lateral horn of spinal cord grey matter from T!-L@ hence thoracolumbar
- short synapse with postganglionic neurones near spinal chord
ANS - Sympathetic:
Postganglionic neurones
- cell bodies are in the sympathetic chain, other named ganglia or in the adrenal medulla; closer to the spinal cord
- long synapse on the target organ
- releases noradrenaline to activate Adrenergenic receptors on target organs
ANS - adrenal medulla - sympathetic supply
- postganglionic axons never develop and the chromaffin cells take on endocrine role as not released by neurone - fight or flight
- release adrenaline or noradrenaline into the bloodstream
- useful for stress reaction, quick use of adrenaline, some NA
ANS - sweat glands - which supply - why useful
- effects of the sympathetic nervous system on sweat glands are mediated by muscarinic receptors because in this special case the postganglionic neurones are also cholinergic
- cholinergic pre and postganglionic usually para sympathetic but is sympathetic in sweat glands and is the exception
- can be useful to detect intoxications or overdose; a drug that affects muscarinic receptors and hence parasympathetic and this special case or sympathetic system affected by drug
Fill in diagram.
Fill in table.
Sympathomimetic drugs
- stimulation, mimicking effect of sympathetic nervous system
- adrenoreceptors agonists are directly acting sympathomimetic drugs
- alteration of release,metabolism, reuptake: indirectly acting sympathomimetic drugs
Sympatholytic drugs
- inhibition (direct and indirect) of sympathetic nervous system
Parasympathomimetic drugs
- stimulation of parasympathetic
- cholinomimetic or cholinergic
Parasympatholytic drugs
Inhibition of parasympathetic nervous system
How can we module the ANS to lower blood pressure?
Sympathetic
Parasympathetic
Adverse effects
Parasympathetic: stimulate (agonist) muscarinic receptors, inhibit acetylcholinesterase enzymes to recent reuptake
Sympathetic: inhibit (antagonists) alpha 1 receptors, no vasoconstriction, inhibit beta 1 lower heart rate and force of contraction of heart, stimulate beta 2 in blood vessels as vasodilation
Adverse:
Parasympathetic: bronchoconstriction, visual disturbances, incontinence, salivation
Sympathetic: tremors, glycogenolysis, bronchodilator
Using a non-selective alpha antagonist to decrease blood pressure was not sustained because
Increases neurotransmitter release as inhibition of alpha 2
So releases noradrenaline concentration which is competing with antagonist and eventually wins increasing blood pressure again
