Lecture 4 Flashcards
Ohms Law
Ina= gn(vm-em)
Initialy for small depolarizations peak gna is very small.
DF is large, product Ina is small
For larger depolarizations to peak gna rises faster than
DF falls, product Ina is larger
For even larger depolarizations peak gna now reaches a maximum constant so the product Ina is now completely dependent on
falling DF so Ina gets smaller until depolarizing Ena=Ina=0
For depolarizing to Vms more positive than Ena, ________________ to rise again but is reversed
the product Ina starts
_______________ the relative conductance of the Na+ channels to various ions
selectivity filter
Li is not a substrate of Na+ and K+ pumps so it accumulates in the cell permanently displacing an equivalent amount of K+ . The reduction in the K gradient results in
a lower Vm until the cell becomes inexcitable. The therapeutic action of small doses of LiCl2 administered to manic depressive patients may be thee result of small modifications in nerve cell excitability
____________________ Is an example of how evolution does no necessarily see,ect for the perfect solution to problem but rather for one that provides a selective advantage however small
The high permeability of the Na+ channel to Li+
Experiment #3:
so far, two way to isolate currents change V com or the ionic concentrations
_____________ selesctiivly blocks voltage dependent Na channels from the japanese puffer fish
TTX tentrodoxin
__________________ selectively blocks voltage dependent K+ channels synthetic
Tea tetraethyl ammonium
What is the sequence of events during a synaptic transmission
- depolarization AP enters the presynaptic terminal
- voltage dependent Ca2+ channels open and Ca2+ ENTERS the presynaptic
- Ca causes synaptic vesicles to migrate the presynaptic membrane
- vesciles dock, lyse-> quintal release of NT into the synaptic cleft (vesicles carry 104 moles of NT)
- NT passively diffuses down its concentration gradient to the post synaptic membrane
- NT binds with specific receptor proteins, the Nt receptor complex undergoes a conformational change which results in an increase in gna in the postsynaptic membrane Ina toward depolarization of the postsynaptic cells
- when depolarization exceeds threshold AP is generated post synaptically -0terminal of NT action
- STorage of Nt presyanptice of vesicles
________ neurotransmitter found in vertebrates at the neuromuscular junction and ganglia of the autonomic nervous system
acetylcholine
_____________ in the basal forebrain contains cells that produce high concentrations of CHAT. Thus these cells have a high probability of being cholinergic
nucleus of basalts meynert
It is interesting that patients who die from alzeheimers disease or how suffered from dementia have __________________
60-90% less chat activity in their cortices than age matched controls
As a result t__________ has become an important focus for alzheimers research
NBM
_____________ blocks ACh release. produced by an anaerobic bacterium. which uses a virus to produce the toxin
botulinum toxin
___________is a common name for various plant extract alkaloid arrow poisons from central and South America . It competitively and reversibly binds to NACHr and has high affinity for nAChR than does ACh . The principle source of this molecule is from two plants
curare
________________ binds irreversibly to nAChR found in thee salivary glands of Many banded (formosan) krait: can be radioactively labeled for autoradiography experiments and use to quantify the nACHr density
alpha bungarotoxin
__________ blocks acetylcholine esterase (Ache) thus blocking Achg hydrolysis and thus proteentioating the effect of Ach hydrolysis antiesteerases
antiesteerases
__________ catalyzes the uptake of Chloe,aceetate is returned to the bloodstream. Heemeicholineium is an example of a synthetic permeate inhibitor, blocks choline reuptake preventing subsequent ACH synthesis
hemicholinium
_____________________ catalyzes the synthesis of ACH
Choline acetyl transferase
________________ is an example of a synthetic CHAT inhibitor that prevents ACh synthesis
CHioline acetyl transferase
___________ is an example of a synthetic Chat inhibitor that prevents synthesis
styrylpyridiine
_______________ a drug or toxin that blocks the normal action of a protein or a biochemical process
inhibitor
An example of an inhibitor that interferes with synaptic transmission at the eNMJ by inhibiting the enzyme AChE is__________________
physostigmine
the term ___________________ refers specifically to the action of substances on receptors sand are often called receptor agonists and receptor antagonists. A receptor agonist blinds to receptor and mimics the action of a naturally occurring neurotranmitter
antagonist or agonists
A receptor antagonist also binds to a receptor but blocks the action of the _____________
neurotransmitter
There are two types of neurotransmitters
iionotrophic and metabotrophic
_________________ are directly associtateted with ion channels. Neurotransmitters binding to an ionotropic receptor causes a direct change in ion movements across the post synaptic membrane
ionotrophic receptors
the nicotinic acetylcholine receptor is an ____________________
inotropic receptor
____________ induction changes in the post synaptic cell that can lead secondarily to changes in the state of ion channels
metabolic receptors
___________ response mediated by metabotropic receptors are generally slower and longer lasting than those induced by iomnotropjic receptors
postsynaptic cells
___________ initiate and in gtraceellular signaling process that can result in the opening or closing of ion channels
metabotrophic receptors
________ are G proteins coupled receptors
metabotrophic receptors
___________________________ mediated by metabotropic receptors are generally slower and longer lasting than those induced by ionotrophic receptors
postsynaptic cell responses
___________ initiate an intracellular signaling process that can result in the opening or closing of ion channels
metabotropic receptors
Metabotropic receptors are ________________________
G protein coupled rreceptors
_______________ receptor to muscarine; blocked by atrophine. These ligand-gated receptors are found where synaptic actions are slower and more subject to metabolic factors
muscarinic acetylcholine recepters
