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Synaptic Transmission
N/A
65
Anatomy
Graduate
01/14/2012

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Term
What are the two primary types of synapses?
Definition
Electrical and chemical
Term
Gap junctions, connexions, electrotonic synapses, and ephaptic connections are all examples of what?
Definition
Electrical synapses
Term
Within the CNS, electrical synapses are most common among what types of cells?
Definition
Glial cells (though also occurs between neurons)
Term
Specializations of cell membranes, most commonly epithelia, where ion channels allow the exchange of ions between cells are characteristic of what type of chemical synapse?
Definition
Ephaptic connections
Term
Ephaptic connections are most common among what types of cells in the CNS?
Definition
Astrocytes
Term
What type of electrical synapse uses connexons to form channels between two nearby cell membranes?
Definition
Gap junctions
Term
Gap junctions allow the transfer of what kinds of substances between synaptic cells?
Definition
Ions
Term
Gap junctions are used in the nervous sytem to allow for a very rapid transmission of information between neurons responsible for what types of actions?
Definition
Oscillatory or rhythmic (ex. olfactory bulb, hypothalamus, eye movement nuclei)
Term
What disease is characterized by defects in genes for connexins that results in demyelination and slowing of conduction in peripheral axons, leading to muscle weakness, atrophy, and sensory loss?
Definition
Charcot-Marie-Tooth disease
Term
The use of chemical substances known as neurotransmitters in order to convey electrical activity between neurons describes what type of synapses?
Definition
Chemical synapses
Term
Which are faster, chemical or electrical synapses? Which allows for more complex information processing?
Definition
Electrical synapses are slower, allow for more complex signals
Term
What are the three primary elements of chemical synapses?
Definition
Presynaptic element (bouton), synaptic cleft, postsynaptic element 
Term
Electrical to chemical transduction in the presynaptic terminal is achieved via depolarization causing the opening of voltage sensitive channels for what ion?
Definition
Calcium
Term
The release of neurotransmitter into the synaptic cleft is controlled through what proteins?
Definition
Calmodulin and synaptotagmin
Term
Neurotransmitter vesicle membranes are recycled through a process involving what proteins?
Definition
Dynamin and clatharin
Term
What type of axons release neurotransmitters along varicosities rather than at the synaptic junction or via vesicular release?
Definition
Autonomic axons, usually sympathetic
Term
Where are large molecule neurotransmitters synthesized?
Definition
Golgi apparatus
Term
What types of neurotransmitters are commonly recycled?
Definition
Small neurotransmitters
Term
What are the two synapse receptor categories?
Definition
Ionotropic, metabotropic
Term
What type of synapse include small molecule synapses, fast synapses, and single messenger synapses?
Definition
Ionotropic synapses
Term
What type of synapses include larger neuropeptide synapses, slow synapses, and second messenger synapses?
Definition
Metabotropic synapses
Term
Activation of ionotropic receptors at postsynaptic axons generally leads to what response?
Definition
Depolarization or hyperpolarization of the postsynaptic membrane
Term
Metabotropic synapses generally cause what type of response in the postsynaptic cell?
Definition
Activation of an enzymatic cascade to produce a product that produces that actual transduction event
Term
What is tthe main advantage to metabotropic synapses?
Definition
Magnification of transduction and regulation of the postsynaptic cell
Term
The majority of metabotropic receptors initate what type of protein mediated pathway?
Definition
G-protein mediated second messengers
Term
What are the most common secondary messengers?
Definition
Adenylyl cyclase, phospholipase C, phospholipase A
Term
Adenylyl cyclase produces what second messenger for protein phosphorylation?
Definition
cAMP
Term
Phospholipase C produces what secondary messengers in order to release calcium stores?
Definition
Phosphoinositol and diacylglycerol
Term
What cascade does phospholipase A initiate?
Definition
Arachidonic acid cascade
Term
Describe the steps of the cAMP system
Definition
Activated receptor -> releases G-protein -> binds to GTP and adenylate cyclase -> converts ATP to cAMP -> stimulates protein kinase A to initiate a response (ex. phsophorylation and opening of sodium ion channels)
Term
The G-protein activated GTP complex in a phospholipase C pathway activates phospholipase C which splits a membrane phospholipid into what two secondary messengers? 
Definition
Diacylglycerol (DAG) and inositol phosphate
Term
Diacylglycerol (DAG) activates what protein in the phospholipase C pathway?
Definition
Kinase C
Term
Destruction of the neurotransmitter or modification by membrane bound enzymes at the synaptic cleft describes what mechanism of removal of neurotransmitters at the synpatic cleft?
Definition
Inactivation
Term
Pinocytosis or direct uptake of neurotransmitters bound to recepors on the postsynaptic cleft describes what mode of neurotrasmitter removal?
Definition
Reputake
Term
Describe the reuptake process of catecholamines
Definition
Inactivated by MAO and COMT, taken up at presynaptic terminal for reuse or diffusion
Term
Astrocytes are particularly active in the regulation and control of what substances?
Definition
Glutamate and GABA
Term
Neurotransmitter receptors on neuroglial cells modulate neuroglial control of what tasks?
Definition
Maintenance of synaptic environment, recycling of transmitters, balance of ions in the extracellular environment
Term
What are the other forms of synaptic communication aside from presynaptic to postsynaptic activation?
Definition
Presynaptic receptor-mediated autoregulation, retrorograde transmission
Term
The process of feedback from the postsynaptic cell is known as what?
Definition
Retrograde transmission
Term
In retrograde trnasmission, the postsynaptic cell responds to synaptic activation by releasing a second chemical messenger that affects the presynaptic cell. Give an example of a retrograde neuromodulator
Definition
NO
Term
The use of receptors on the presynaptic membrane that bind to the neurotransmitters released at the presynaptic cleft describes what form of regulation?
Definition
Presynaptic autoregulation
Term
What part of the heart uses presynaptic autoregulation?
Definition
Sinoatrial node (negative feedback)
Term
Why is retrograde transport important to the neuron?
Definition
Neuromodulation via retrograde transport is an essential part of cell maintenance. Both the neuron and its target cell may die if this connection is severed.
Term
Phosphorylation of neurotransmitter-bound receptors initiating a reduction in their binding or transduction efficiency describes what type of receptor regulation?
Definition
Desensitization
Term
Invaginations internalizing receptors for desensitization are called what?
Definition
Caveoli
Term
A decrease in receptor number by means of degredation or regulation of transcription is referred to as what?
Definition
Downregulation (converse is known as upregulation)
Term
The loss of neuronal contact with a cell may result in a larger than normal increase of receptors via upregulation. This is known as what?
Definition
Denervation supersensitivity
Term
What are the amino acid neurotransmitters?
Definition
Glutamate, GABA, glycine
Term
What are the biogenic amine neurotransmitters?
Definition
Acetylcholine, monoamine, catecholamines, serotonin, histamine
Term
What are the neuropeptide neurotransmitters?
Definition
VIP, substance P, enkephalins, endorphins, orexin, oxytocin, vasopressin
Term
What are the purine neurotransmitters?
Definition
Adenosine, ATP
Term
What are the gaseous neurotransmitters?
Definition
Nitric oxide, carbon monoxide
Term
What ist he most prevvalent excitatory neurotransmitter in ths CNS?
Definition
Glutamate
Term
How is glutamate synthesized for use in the CNS?
Definition
From alpha-ketoglutarate by GABA transaminase
Term
What glial cell aides in the recycling of glutamate?
Definition
Astrocytes
Term
What is the primary inhibitory neurotransmitter in the brain?
Definition
GABA
Term
In what part of the brain is GABA found in high amounts?
Definition
Striatum and lentiform nuclei, hypothalamus, hippocampus, periaqueductal gray, purkinje cells of the cerebellum
Term
What is the primary inhibitory neurotransmitter in the brainstem and spinal cord?
Definition
Glycine
Term
What neurotransmitter is important in both the CNS and PNS with both excitatory and inhibitory properties through both inotropic and metabotropic receptors?
Definition
Acetylcholine
Term
What type of neurotransmittters are synthesized from tyrosine to create the neurotransmitters dopamine, norepinepherine, and epinepherine to produce both excitatory and inhibitory effects?
Definition
Catecholamines
Term
What is the major enzyme involved in the inactivation and recycling of catecholamines?
Definition
Catechol-O-methyl transferase (COMT)
Term
What biogenic amine neurotransmitters is synthesized from tryptophan to elicit both excitatory and inhibitory effects, particularly dealing with emotional behavioral states?
Definition
Serotonin
Term
What excitatory biogenic amine neurotransmitor is synthesized by histidine decarboxylase?
Definition
Histamine
Term
Neuropeptide neurotransmitters use what types of receptors?
Definition
Metabotropic and G-protein coupled
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