Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
Define the criteria for accepting a substance as a (classical) neurotransmitter
|
1. localization- localized to the presynaptic element & present w/i presynaptic neuron
2. release- released from presynaptic element upon activation of terminal & depolarization of neuron 3. identity- action on target cells is same as effects on presynaptic neuron by transmitter |
|
Describe the distribution of Glutamate
|
-most prevalent fast excitatory transmitter in CNS
-used by about 1/2 neurons in brain |
|
Describe the synthesis of Glutamate
|
Its derived from a-ketoglutarate by GABA transaminase, which is also a precursor for the inhibitory neurotransmitter g-aminobutyric acid (GABA).
-derived from glutamine & converted to glutamate & ammonia by mitochondria |
|
Describe the inactivation mechanisms of Glutamate
|
-reuptake directly by presynaptic terminal transporters
-indirectly through astrocyte transporters -converted back to glutamine & transported back to terminal |
|
Describe the functions of Glutamate
|
-role in learning & memory
-Ca2+ ion entry through NMDA activated channels in ischemic tissue ^can exacerbate injury & increase cell death -associated w/ excitotoxicity |
|
Describe the distribution of GABA
|
-primary inhibitory neurotransmitter in brain
-found in high amnts in substantia nigra stratum, lentiform nuclei, hypothalmus, hippocampus, periaqueductal gray |
|
Describe the synthesis of GABA
|
-GABA is synthesized from glutamate by glutamic acid decarboxylase.
-It is also converted from glutamine-->glutamate --> GABA |
|
Describe the inactivation mechanisms of GABA
|
The recycling mechanisms are therefore similar to glutamate, except for the additional step of conversion back to glutamate from glutamine in both neurons and astrocytes.
|
|
Describe the functions of GABA
|
-transmitter for Purkinje cells of cerebellum
-linked to chloride ion channels, usually hyperpolarizes, occasionaly excitatory -associated w/ drug effects: anesthetics, caffeine, alcohol |
|
What AA neurotransmitter is implicated in epilepsy, bipolar disorder, schizophrenia, & anxiety disorders
|
GABA
|
|
Describe the distribution of Acetylcholine
|
-in CNS & PNS
-CNS: motor & preganglionic autonomic neurons use it. -excitatory & inhibitory properties -ionotropic & metabotropic receptors. -broadly projecting ACh systems that are part of conscious arousal. |
|
Describe the synthesis of Acetylcholine
|
synthesized from choline and acetyl Coenzyme A by choline acetylase
|
|
Describe the inactivation mechanisms of Acetylcholine
|
After release, acetylcholine is broken down by acetylcholinesterase to choline and acetic acid. Both components are transported into the terminal and recycled
|
|
Describe the functions of Acetylcholine
|
involved in diverse functions from memory to muscle contraction
|
|
What does the loss of acetylcholine containing neurons in the nucleus basalis (brain) lead to?
|
Alzheimer's disease
|
|
Describe the distribution of Dopamine & Norepinephrine
|
-throughout nervous system
-both excitatory & inhibitory |
|
Describe the synthesis of Dopamine & norepinephreine
|
tyrosine-->dopamine-->norepinephrine
|
|
Describe the inactivation mechanisms of Dopamine & norepinephrine
|
-inactivation and recycling by catechol-O-methyl transferase (COMT) on the post synaptic membrane and monoamine oxidase (MAO) in the presynaptic terminal cytoplasm.
|
|
Describe the functions of Dopamine & norepinephrine
|
-modulate consciousness, sleep, & motor activity in brain
-motor functions, rewarding behaviors/addiction |
|
Why are most of the enzymes involved in this pathway significant?
tyrosine-->dopamine-->norepinephrine -->epinephrine |
tyrosine--(amino acid hydrolase)--> DOPA
DOPA--(dopa decarboxylase)--> dopamine dopamine--(dopamine b-hydroxylase)--> NE NE--(phentolamine N- methytransferase)--> EPI *are modifiable by pharmocologic or toxic agents. |
|
What neurotransmitter is involved in Parkinson disease?
|
dopamine
|
|
Many antipsychotic drugs have their primary actions on ____________ receptors
|
catecholamine
|
|
Describe the distribution of serotonin
|
excitatory & inhibitory
|
|
Describe the synthesis of serotonin
|
synthesized from tryptophan by subsequent actions of tryptophan hydroxlase, and 5-hydroxytryptophan decarboxylase.
|
|
Describe the inactivation mechanisms of serotonin
|
-broken down by monoamine oxidase and or transported back into the presynaptic terminal.
|
|
Antidepressents work through inhibiting the reuptake of ____________ or through inhibiting monamine oxidases (MAOI)
|
serotonin (SSRIs)
|
|
Describe the functions of serotonin
|
- sleep/wake cycles, emotional behavioral states & prominent component of platelets (vasoconstriction).
-associated with the action of may hallucinogens (LSD, mescaline, ecstasy). |
|
Describe the distribution of histamine
|
-excitatory
-component of mast cells and basophils (vasodilation) and involved in gastric secretion. |
|
Describe the synthesis of histamine
|
synthesized from histidine by histidine decarboxylase.
|
|
Describe the inactivation mechanisms of histamine
|
-broken down by histamine N methyltransferase and diamine oxidase.
Antihistamines are generally receptor blockers. |
|
Describe the functions of histamine
|
Centrally, it is associated with sleep/wake cycles an the maintenance of a conscious state
|
|
Describe the properties of neuropeptides in the CNS
|
-located in the CNS and PNS
*substance P, b-endorphin, enkephalins and vasoactive intestinal polypeptide (VIP). -all metabotropic and G-protein coupled -Release is often non-synaptic or as a co-transmitter -Centrally, neuropeptides are prominent in the hypothalamus, also found in the brainstem and basal ganglia. *oxytocin & vasopressin |
|
Describe the functions of neuropeptides in the CNS
|
-many have primary functions related to enteric nervous system
-major roles in autonomic function (oxytocin, vasopressin) -pain (substance P) -pain/pleasure (b-endorphin & enkephalon) -circadian rhythm (VIP) |
|
Describe the properties of purines in the CNS
|
-ATP & Adenosine are synthesized & recycled through the same pathways for energy metabolism in mitochondria.
-ATP is often a co-transmitter packaged with other neurotransmitters (noradrenaline & neuropeptide Y) |
|
Describe the functions of purines in the CNS
|
-released from sympathetic perivascular nerve fibers and act on vascular smooth muscle, constricting or relaxing depending on receptor
-act on purine autoreceptors to effectively regulate their own release and that of any cotransmitter |
|
Describe the properties of nitric oxide as a transcellular messenger in the CNS
|
-gasotransmitters
-interact as cotransmitter -sympathetic enzymes present in neurons of brain *Nitric oxide responses are mediated through a cGMP mechanism in both neurons and neuroglia |
|
Describe the functions of nitric oxide as a transcellular messenger in the CNS
|
-mediate numerous effects in body tissue particularly related to vascular smooth muscle.
- a neuromodulator at the synaptic level in both a feed forward and feedback (retrograde) regulation of synaptic activity. |
|
Describe the properties of endocannabinoids as a transcellular messenger in the CNS
|
-synthesized from arachidonic acid derivatives
-degraded by fatty acid amide hydrolase and monacylglycerol lipase. -act through two primary receptors CB1 (nervous system, and organs) and CB2 (immune system |
|
Describe the functions of endocannabinoids as transcellular messenger in the CNS
|
-In the nervous system, modulate synaptic transmission as a retrograde feedback effect.
-effect physiological processes associated w/ appetite, pain sensation, mood and memory |
|
What is retrograde transmission?
|
-proccess of feedback from postsynaptic cell
-postsynaptic cell responds to synaptic activation by releasing a second chemical messenger capable of affecting the presynaptic nerve terminal or neuron. . |