TASK 3 Flashcards
_Neurotransmitter
They are also called synaptic transmitter, chemical transmitter, or simply transmitter. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons. So, NEURONS integrate electrical information from many synapses and may then release a chemical or neurotransmitter – an endogenous substance that communicates the result of that information processing to the postsynaptic cell
To be considered a neurotransmitter, a substance should meet the following criteria
_the substance exists in presynaptic axon terminals _the presynaptic cell contains appropriate enzymes for synthesizing the substance _the substance is released in significant quantities when action potentials reach the terminals _specific receptors that recognize the released substance exist on the postsynaptic membrane _experimental application of the substance produces changes in postsynaptic cells _blocking release of the substance prevents presynaptic activity from affecting the postsynaptic cell
receptor
A protein molecule that binds and reacts to molecules of a neurotransmitter or hormone
_metabotropic receptor
– a receptor protein that does not contain an ion channel but may, when activated, use a G protein system to alter functioning of the postsynaptic cell
_G protein
– act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. There are two classes of G proteins. _monomeric small GTPases, _heterotrimeric G protein complexes
_monomeric small GTPases,
It is a kind of G PROTEIN
_heterotrimeric G protein complexes
It is a kind of G PROTEIN, composed by subunits _alpha (α) _beta (β) _gamma (γ)
_ionotropic receptor
– a receptor protein that includes an ion channel that is opened when the receptor is bound by an antagonist LEADS TO _Excitatory postsynaptic potential (EPSPs) _inhibitory postsynaptic potential (IPSPs)
_transporters
– specialized receptors in the presynaptic membrane that recognize neurotransmitter molecules and return to the presynaptic neuron for reuse
_exogenous
– arising from outside the body
_endogenous
– arising from inside the body
_ligand
– substance that binds to receptor molecules
TYPES OF NEUROTRANSMITTERS
_amino acid neurotransmitters _amine neurotransmitters _peptide neurotransmitters _gas neurotransmitters
_amino acid neurotransmitters
a neurotransmitter that is itself an amino acid _GABA _Glycine _Glutamate _Aspartate
_GABA
(gamma-aminobutyric acid) – typically has an inhibitory effect. Most of them (as Valium) are potent tranquillizers _GABA A - ionotropic receptors (gated chloride channels) – when activated they produce fast inhibitory postsynaptic potentials. It is made up by 5 protein subunits surrounding a Cl- ion channel, different combinations of those protein, thus different kinds of GABA A _GABA B – metabotropic receptors, typically producing a slow occurring inhibitory postsynaptic potential _GABA C – receptors that are ionotropic with a chloride channel, but they differ from other GABA receptors in certain details of their subunit structure IT IS A GABA, AMINOACID NEUROTRANSMITTER
_GABA A
- ionotropic receptors (gated chloride channels) – when activated they produce fast inhibitory postsynaptic potentials. It is made up by 5 protein subunits surrounding a Cl- ion channel, different combinations of those protein, thus different kinds of GABA A IT IS A GABA, AMINOACID NEUROTRANSMITTER
_GABA B
– metabotropic receptors, typically producing a slow occurring inhibitory postsynaptic potential IT IS A GABA, AMINOACID NEUROTRANSMITTER
_GABA C
– receptors that are ionotropic with a chloride channel, but they differ from other GABA receptors in certain details of their subunit structure IT IS A GABA, AMINOACID NEUROTRANSMITTER
_glycine
– typically has an inhibitory effect, AMINO ACID NEUROTRANSMITTER
_glutamate
– an amino acid neurotransmitter, the most common excitatory transmitter
_glutamatergic
– referring to cells that use GLUTAMATE as their synaptic transmitter
_excitotoxicity
– the property by which neurons die when overstimulated , as with large amount of GLUTAMATE(produced in phenomenon in which neural injury is involved, such as a stroke or trauma)
_aspartate
– an amino acid neurotransmitter that is excitatory at many synapses
_amine neurotransmitters
a neurotransmitter based on modifications of a single amino acid _quaternary amines _monoamines
_quaternary amines
acetylcholine (ACh)
acetylcholine (ACh)
distributed by neurons called _cholinergic – neurons that distribute acetylcholine in the brain TWO TYPES of acetylcholine _nicotinic (nACh) – most of them are ionotropic , responding rapidly and having an excitatory effect _muscarinic (mACh) – they’re G protein-coupled (metabotropic) receptors, so they have slower responses when activated , and they can be either excitatory or inhibitory. They can be blocked by atropine or scopolamine (drugs)
_nicotinic (nACh)
– most of them are ionotropic , responding rapidly and having an excitatory effect TYPE OF acetylcholine (ACh)
_muscarinic (mACh)
– they’re G protein-coupled (metabotropic) receptors, so they have slower responses when activated , and they can be either excitatory or inhibitory. They can be blocked by atropine or scopolamine (drugs) TYPE OF acetylcholine (ACh)
_cholinergic
– neurons that distribute acetylcholine in the brain
_monoamines
_indoleamines _catecholamine amino neurotransmitters
_indoleamines
modified amino acids derived from the amino acid tryptophan _serotonin (5-HT) _melatonin amino neurotransmitters, MONOAMINES
_catecholamine
derived from the amino acid tyrosine _dopamine (DA) and hippocampus. _norepinephrine (NE) _epinephrine (adrenaline) amino neurotransmitters, MONOAMINES
_serotonin (5-HT)
– a neurotransmitter that is produced in the raphe nuclei (midbrain and brainstem) and is active in structures throughout the cerebral emispheres (only 200 million of the 80-90 billion neurons of the human brain are serotonergic, but they exert widespread influence through the rest of the brain) amino neurotransmitters, monoamines , INDOLAMINES
_serotonergic
- neurons that use serotonin as their synaptic transmitter
_melatonin
amino neurotransmitters, monoamines , INDOLAMINES
dopamine (DA)
– about a million neurons contain dopamine. Found in the midbrain – especially the substantia nigra and basal forebrain. They follow two main pathways _mesostriatal pathway _mesolimbocortical pathway amino neurotransmitters, monoamines , CATECHOLAMINE
_mesostriatal pathway
PATHWAY FOR DOPAMINE ,substantia nigra to stratium (caudate and putamen)
_mesolimbocortical pathway
PATHWAY FOR DOPAMINE ventral tegmental area (VTA) to nucleus accumbens, cortex (including the insula), and hippocampus.
_norepinephrine (NE)
– produced and released by symphatetic postgangliolic neurons to accelerate organ activity. Also produced in the brainstem by _locus coeruleus – in the pons , literally “blue spot” a small nucleus in the brainstem whose neurons produce norepinephrine , or better noradrenergic cells in the locus coeruleus produce them __amino neurotransmitters, monoamines , CATECHOLAMINE
_locus coeruleus
– in the pons , literally “blue spot” a small nucleus in the brainstem whose neurons produce norepinephrine , or better noradrenergic cells in the locus coeruleus produce them
_epinephrine (adrenaline)
amino neurotransmitters, monoamines , CATECHOLAMINE
_peptide neurotransmitters
a neurotransmitter consisting in a short chain of amino acids _opioid peptides _other neuropeptides
_opioid peptides
A group of endogenous substances with actions that resemble those of opiate drugs like morphines _Enkephalins _met-enkephalin _leu-enkephalin _Endorphins _ β-endorphin _Dynorphins _dynorphin A IT IS A PEPTIDE NEUROTRANSMITTER
_other neuropeptides
_neuropeptide Y (NPY) ¬_oxytocin _substance P _cholecystokinin (CCK) _vasopressin _hypothalamic releasing hormones
_Enkephalins
peptide neurotransmitters, OPIOID PEPTIDES
_Endorphins
peptide neurotransmitters, OPIOID PEPTIDES
_Dynorphins
peptide neurotransmitters, OPIOID PEPTIDES
_gas neurotransmitters
a soluble gas that is produced and released by a neuron to alter the functioning of another neuron _nitric oxide (NO) _carbon monoxide
_retrograde transmitter
– function of NO (nitric oxide) , it diffuses from the postsynaptic neuron back to the presynaptic neuron
_agonist
– (exogenous ligand-drug- or endogenous –transmitters) influence normal activity of synapses by initiating a response like that of another molecule (neurotransmitter probably) – open the ion channel _non-competitive agonists
_non-competitive agonists
agonist binds to target receptors at a site that is different from where the endogenous ligand binds, in the case of the agonist the channel opens
_antagonist
– influence normal activity of synapses blocking action of a neurotransmitter, channel stays close _competitive antagonists _non-competitive antagonists
_competitive antagonists
– block agonists from binding to the receptors
_non-competitive antagonists
- antagonist binds to target receptors at a site that is different from where the endogenous ligand binds, in the case of the antagonist the channel stays close
_inverse agonist
– a substance that binds to a receptor and causes it to do the opposite of what the naturally occurring transmitter does
_partial agonist
– a drug that, when bound to a receptor, has less effect than the endogenous ligand would
_binding affinity
– the propensity of molecules of a drug (or other ligand) to bind to receptors
_dose-response curve (DRC)
– graph that shows drug doses and observed effects
_tolerance
– condition in which with repeated exposure to a drug , an individual becomes less responsive to a constant dose. It can develop in several ways: _metabolic tolerance _functional tolerance
_metabolic tolerance
– the form of drug tolerance that arises when repeated exposure to the drug causes the metabolic machinery of the body to become more efficient at cleaning the drug TYPE OF DRUG TOLERANCE
_functional tolerance
– decreased responding to a drug after repeated exposures, generally as a consequence of up- or down-regulation of receptors _up-regulation _down regulation TYPE OF DRUG TOLERANCE
_up-regulation
– a compensatory INCREASE in receptor availability at the synapses of a neuron HAPPENS IN FUNCTIONAL TOLERANCE
_down regulation
a compensatory REDUCTION in receptor availability at the synapses of a neuron HAPPENS IN FUNCTIONAL TOLERANCE
_cross-tolerance
- a condition in which the development of tolerance for one drug causes an individual to develop tolerance for another drug TYPE OF DRUG TOLERANCE
TOLERANCE CAUSES
_withdrawal symptom _sensitization
_withdrawal symptom
– uncomfortable symptom that arises when a person stops taking a drug that he/she has used frequently, especially at high doses
_sensitization
– a process in which some drug responses can became STRONGER with repeated treatments. It is thought to contribute to the drug craving that addicts experience
_bioavailable
– referring to a substance, usually a drug, that is present in the body in a dorm that is able to interact with physiological mechanisms
THE DURATION OF A DRUG EFFECT IS LARGELY DETERMINED BY THE MANNER IN WHICH THE DRUG IS METABOLIZED AND EXCRETED FROM THE BODY
(via kidneys, liver, lungs and other routes)
_biotransformation
– process in which enzymes convert a drug into a metabolite (intermediate and product of metabolism) that is itself active, possibly in ways that are substantially different from the actions of the original substance
_pharmacokinetics
– collective name for all the factors that affect the movement of a drug into, through, and out the body
_blood-brain barrier
– the thigh conjunctions between the endothelial cells of blood vessels within the CNS that inhibit the movement of larger molecules out of the bloodstream and into the brain. This barrier poses a major challenge for neuropharmacology because many drugs that might be clinically or experimentally useful are too large to pass the blood-brain barrier to enter the brain.
_Local anaesthetic
- a drug, such as procaine or lidocaine, that blocks sodium channel to stop neural transmission in pain fibres
_autoreceptor
– a receptor for a synaptic transmitter that is located in the presynaptic membrane, telling the axon terminal how much transmitter has been released
_adenosine
- in the context of neural transmission, a neuromodulator that alters synaptic activity
_transmitter reuptake
– same drugs interfere with it, it is the reabsorption of synaptic transmitter by the axon terminal from which it was released
_degradation
– drug effect, chemical breakdown of neurotransmitter into inactive metabolites
SYNAPTIC TRANSMISSION
SYNAPSES MAKE ELECTRICAL SIGNALS THAT TURN IN CHEMICAL ONES
METABOTROPIC AND MONOTROPIC RECEPTORS
SYNAPTIC TRASMITTORS AND FAMILIES
FUNCTION /SUBTIPES OF RECEPTORS
DRUG EFFECTS PRESYNAPTIC LEVEL
DRUGS EFFECTS POSTSYNAPTIC LEVEL
ROUTES OF ADMINISTRATION AND TYPES OF DRUGS
