Neurotransmitters Flashcards
What could happen after a NT has had its effect on the target cell?
Re-uptake, enzymal inactivation and diffusion.
What are the 2 types of NT receptors?
Ionotropic and metabotropic.
What are the 3 types of NTs?
AAs, biogenic amides and peptides.
What are examples of AA NTs?
Glutamate, GABA and glycine.
What comprises the biogenic amines?
Catecholamines and indolamines.
What are examples of catecholamines?
Noradrenaline, adrenaline and dopamine.
What is an example of an indolamine?
Serotonin.
What are examples of peptide NTs?
Encephalin, endorphin and dynorphin.
What is the function of glutamate as a NT?
Primary excitatory NT in the CNS.
What is glutamate involved in?
Memory, learning and cell death.
What does GABA stand for?
Gamma- aminobutyric acid.
What is the function of GABA?
Principal inhibitory NT in the CNS.
How does GABA act?
Via chloride channels.
What is the function of glycine in the CNS?
Second most common inhibitory NT in the CNS.
What is the function of glycine outside the CNS?
Primary inhibitory NT in the spinal cord and brainstem.
What type of post-synaptic receptor does glutamate use?
Mostly via ionotropic receptors
What are the 3 types of ionotropic receptors that glutamate uses?
NMDA, Kainate and AMPA.
What ions do NMDA receptors allow the passage of?
Calcium ions.
Which ions do the Kainate receptors allow the passage of?
Sodium and potassium ions.
Which ions do the AMPA receptors allow the passage of?
Permeable to cations (positive).
Where does glutamate act?
Widespread in the CNS.
Where do glutamate neurons span in the CNS?
Hemispheres and descending to the brainstem or spinal cord.
What is synaptic plasticity?
Process by which synapses are strengthened or weakened by feedback mechanisms.
What is synaptic plasticity used for?
For storing long or short term memories.
What is excitotoxicity?
Excessive stimulation of NMDA receptors causes a large influx of calcium ions.
What can excitotoxicity result in?
Cell death.
What is dysfunction of glutamate NT linked to?
Karl Lashley’s visual aura in migraines.
What mental disorder is glutamate implicated in?
Cortical spreading depression (CSD).
Which brain disorder is glutamate dysfunction linked to?
Epilepsy.
How does glutamate dysfunction cause epilepsy?
Excess excitation causes a feedback loop, uncontrolled excitation causes over expanding in brain.
What can epilepsy begin as?
Partial seizures.
What happens if partial seizures become more uncontrolled?
They can become Grand Mal seizures.
What can epileptic seizures be treated with?
Phenytoin and Benzodiazepines.
How does phenytoin treat epilepsy?
Increases the refractory period between firings in voltage gated sodium channels.
How does benzodiazepines treat epilepsy?
Increase the action of GABA (inhibitory).
What is the mechanism of benzodiazepines on GABA channels?
When benzodiazepines are bound, GABA can open the channel more often.
Are benzodiazepines specific?
They only enhance the action of existing GABA molecules.
Where is GABA mainly found?
In the interneurons of the CNS.
Where is GABA also found?
In striatum and globus pallidus.
What does GABA act on?
Ligand gated chloride channels.
What is GABA inactivated by?
Presynaptic reuptake.
What does alcoholism cause?
A change in GABA transmission.
What does withdrawal of alcohol from an alcoholic result in?
Convulsive movements and seizures.
What can alcoholism be treated with?
Benzodiazepines and phenytoin.
What is tetanus caused by?
Toxin from clostridium tetani.
How does tetanus cause disease?
Inhibits release of glycine and shifts excitation-inhibition balance.
What are the mild effects of tetanus?
They are restricted to muscles innervated by cranial nerves.
What are the more serious effects of tetanus?
Epileptiform fits.
What is tetanus treated with?
Anti-toxin and benzodiazepines.
What is dopamine?
A NT and neuromodulator.
What is dopamine involved in?
Pleasure, addiction and movement.
Which system is noradrenalin involved in?
The sympathetic (fight or flight) NT.
What is decreased potentiality of noradrenaline associated with?
Parkinson’s and ADHD.
Where are all catecholamines synthesized?
In the bouton and inactivated by reuptake.
What is adrenaline involved in?
The sympathetic system.
Where is adrenaline produced?
A peripheral hormone from the adrenal medulla.
What is the synthesis route order of catecholamines?
Tyrosine, DOPA, dopamine, noradrenaline and finally adrenaline.
What are adrenoreceptors?
G-protein linked metabotropic receptors for noradrenaline.
Which areas of the brain does noradrenaline work in?
Locus coeruleus and medulla/hypothalamus.
For what processes is noradrenaline used in the locus coeruleus?
Sleep, wakefulness, alertness and attention.
For what is noradrenaline controlling in the medulla?
Feeding behaviour.
For what is noradrenaline controlling in the hypothalamus?
Blood pressure regulation.
What are dopaminergic receptors?
G-protein linked metabotropic receptors.
Where does dopamine work in the brain?
Nigrostriatal, mesolimbic and mesocortical and the tuberohypophyseal system.
What is dopamine controlling in the nigrostriatal area in the brain?
Motor control.
What is dopamine controlling in the mesolimbic and mesocortical areas of the brain?
Behavioural effects.
What is dopamine controlling in the tuberohypophyseal system?
Endocrine control via the anterior pituitary.
How is dopamine linked to Parkinson’s?
Symptoms due to depleted dopamine in the motor coordinated circuits.
What are the symptoms of Parkinson’s linked to dopamine dysfunction?
Tremor, muscle rigidity and bradykinesia or akinesia.
What does bradykinesia mean?
Slowness of movement.
What does akinesia mean?
Loss of ability to move muscles voluntarily.
How is dopamine dysfunction linked to Schizophrenia?
Over production of dopamine in the mesolimbic system.
What is used to treat Schizophrenia?
Antipsychotics.
How is addiction linked to dopamine?
Works through pleasure centres of the CNS located in the mesolimbic dopamine system.
Where in the brain does serotonin work?
Locus coeruleus and the Raphe nuclei.
What processes is serotonin involved in the locus coeruleus?
Sensory signals.
What processes is serotonin involved in the raphe nuclei?
Sleep, wakefulness and mood.
Which mental disorders are associated with serotonin?
Depression and OCD.
How is depression and OCD treated?
With serotonin reuptake inhibitors such as Fluoxetine.
What is Fluoxetine also known as?
Prozac
How are the effects of MDMA caused?
By causing the release and preventing subsequent reuptake of serotonin.
How is serotonin involved in some drugs of abuse?
Receptor agonists include LSD, psilocybin and mescaline.
Where are peptide NTs made?
In the cell body and transported to the bouton.
Which peptide NTs are implicated in schizophrenia?
Neuropeptide Y, neurotensin and cholecystokinin.
What is substance P involved in?
Pain transmission.
What are the effects of endorphins and encephalins on opioid receptors?
They act on opioid receptors as endogenous ligands.
What are examples of opioids?
Morphine, codeine, pethidine, methadone and diamorphine.
What do opioids do to opioid receptors?
Cause downregulation of opioid receptors in the CNS.
What does downregulation of opioid receptors cause?
Opioid tolerance and increased tolerance.
Where are opioid receptors also present?
In the limbic system and periaqueductal grey.
What can reduce opioid withdrawal symptoms?
Naloxone as an opioid receptor antagonist.
Where is acetylcholine found?
In the peripheral and CNS as well as neuromuscular junctions.
Which areas of the brain are essential for formation of new memories and learning?
The hippocampus and cortex.
In the CNS, where do neurons project into?
The hippocampus and cortex.
Which disease is associated with dysfunction of ACh in the CNS?
Alzheimer’s disease.
How does nicotine affect the body?
Acts on nicotonic acetylcholine receptors found in the CNS and PNS.
What do anticholinesterases do?
Prevent the breakdown of ACh and prolong its activity.
What are the therapeutic uses of anticholinesterases?
Donepezil in Alzheimer’s.
What are the toxic uses of anticholinesterases?
Insecticides and nerve gases.
