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27 Cards in this Set

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  • Back
What type of neuroeffector junctions are found in s.muscle, cardiac muscle and exocrine glands?
postganglionic neuroeffector junctions
What is the major CNS excitatory NT?
Glutamic acid
What are the major CNS inhibitory NTs?
glycine and GABA
Where are non-peptide transmitters (ACh and NE) made and stored?
presynaptic terminals
What causes the release of Ca++ in the presynaptic vessicle?
depolarization-->voltage gated Ca++ channels open
What does Ca++ do in the presynaptic vessicle?
mobilization and fusion of NT vessicles on the inner membrane surface near dense bodies, which leads to the docking and formation of a fusion pore
Do NT release spontaneously in the absence of APs?
yes, at active site (dense bodies). They are called spontaneous miniature potentials
What is an ionotropic receptor?
ligand gated ion channel
What is a metabatropic receptor
G-protein coupled receptor
What type of receptors (ligand gated or G-protein couple) do you find in the PNS and the CNS?
PNS: G-protein coupled (metabatropic)… CNS: both Ligand gated (ionotropic) and metabatropic
About how many molecules of ACh are found in on quantum (vessicle)?
~10,000
What type of receptors are found on the post-synaptic vessicles?
Ligand-gated
Is the binding of NT to ligand-gated ion channels reversible?
Yes
What type of receptors do you find at autonomic neuroeffector junctions?
G-protein receptors
What types of receptors do you find at CNS synapses?
Ligand-gated and G-protein receptors
Are Ligand-gated ion channels selective? Give an example of one? How many ACh channels must bind for activation of the channel?
a) no, they allow Na, K and Ca, b) ACh nicotinic receptor allows Na, K and Ca ion, c) two
What type of Potential is produced at ligand-gated receptors that allow a flow of Na, K, and Ca down their electrochemical gradient?
excitatory postsynaptic potential (EPSP), but at neuromuscular junction end-plates it's usually called an end-plate potential (EPP)
What type of Potential is produced at ligand-gated receptors that allows the diffusion of Cl ?
Inhibitory postsynaptic potential (IPSP)
Detail the G-protein cascade that leads to the opening of an G-protein ion channel.
As an example the G-protein second messenger system: binding of NT --> GDP --> GTP (active form) --> activation of adenylyl cyclase --> ATP --> cAMP (second messenger)--> activation of protein kinase (PK) --> phosphorylation of channel P --> ionic flow
What type of receptors are muscarinic receptors? How does it function in cardiac pacemaker cells?
G-protein receptor… NO SECOND MESSENGER, instead the directly acts on K+ membrane channels causing them to open and slow the HR
What type of receptors are ß-adrenergic receptors? How does it function in myocardial cells?
G-protein coupled… In myocardial cells when the ß-adrenoceptor is bound by the sympathetic transmitter, NE --> causes the influx of Ca++ (through L-type Ca++ channels) --> causing an increase in HR
What occurs as a result of ACh binding to muscarinic, (G-protein second messenger system) cholinoceptor?
K+ channel pore opens and allows the efflux of K down its electrochemical gradient.
Where are ACh muscarinic, (G-protein second messenger system) cholinoceptor found?
Vagus nerve, parasympathetic, innervation of the heart, which slows the heart.
What is another name for and EPSP at a neuromuscular junction?
EPP
Which are longer in duration, ligand-gated or G-protein coupled receptors?
G-protein coupled receptors, which can also produce significant amplification
What 5 things determines the time that it takes for a membrane potential to return to its pre-AP membrane potential?
1) number of NT release, 2) NT receptors, 3) rate of NT removal, and 4) G-protein (longer, amplified) process, 5) membrane capacitance (passive property)
Give 3 ways NTs are removed and/or inactivated?
diffusion from cleft, enzymatic b/d, re-uptake