lecture 3 Flashcards
ionotropic receptors are also known as ___________. include examples and time scale
ligand gated channels; nicotinic, ACh receptors, GABA, glutamate receptors; milliseconds b/c transmitter binds outside and causes conformational change –> hyperpolarization/depol –> cellular effects
metabotropic receptors are also known as __________. include exmaples and time scale
G-protein coupled receptors; muscarinic, ACh receptor; seconds b/c second messengers can activate stuff like effectors, calcium release, protein phosphorylation, etc.. –> cellular effects
what receptors take minutes? hours?
kinase linked receptors; nuclear receptors
What is the story of Opechancanough?
physostigmine vs tubocurare
tubocurare - bind to same receptor as acetylcholine, stop channel from opening (non-depolarizing blocking agents)
nerve agents are a class of _______ that block __________, an enzyme that normally destroys acetylcholine
organophosphates; acetylcholinesterase
too much acetylcholine can lead to
flaccid paralysis
toxic reactions of muscarinic receptors due to nerve gases
DUMBELL - diarrhea, urination, miosis, bronchoconstriction/bradycardia, emesis, lacrimation, loss of muscle strength
excitation-contraction coupling is the…
rapid communication btwn electrical events occurring in the plasma membrane of skeletal muscle fibres and Ca2+ release from the SR, which leads to contraction
ACh at the NMJ are exclusively nicotinic or muscarinic?
nicotinic
molecular machines governing exocytosis of synaptic vesicles
SNARE complex (synaptobrevin, syntaxin, Snap25)
botulinim toxin
proteases that chop up the SNARE complex! work by inhibiting the release of GABA therefore leading to more excitation in the tissue and yeah – “sausage poison” bc it’s from raw meat or heroin– muscle weakness, breathing difficulties, paralysis, death – BTX-A is the cosmetic botox
nicotinic receptor structure has how many subunits
5, each composed of a transmembrane protein that has 4 membrane spanning alpha helical regions (m1, m2, m3, m4)
what is an example of a toxin that stops acetylcholine from binding
bungarotoxin, snake toxin
acetylcholine does what
depolarize cell and cause muscle contraction
why does continuous end plate depol cause muscle relaxation?
bc sodium channels rapidly inactivate, making it harder to repolarize (so depolarizing blocking agents can essentially act like nondepolarizing muscle relaxants) — in other words nicotinic receptors are basically desensitized
TOF phenomenon
if you give enough blocking agent (neuromuscular blockers on pre and postsyanptic nAChRs) you get a specific pulse
less acetylcholine in hippocampus is an effect of which brain disease
alzheimers
LTP, which promotes learning, is associated with which neurotransmitter
acetylcholine
alzheimers cholinergic hypothesis
caused by reduced acetylcholine
alzheimers drugs for early stages
aricept (donepezil), exelon (riavastigamine)
alzheimers due to what in the brain
amyloid plaques - neurofibrillary tangles of the tau protein – loss of synapses and neurons in hippocampus and entorhinal cortex
stigmines inhibit what
acetylcholinesterases
