phys review Flashcards
MOA of TTX
blocks voltage gated NaChs
what will most rapidly hypopolarize a cells RMP
blockage of K leak channels
inhibition of Na/K pump will do this too, just takes longer
dendrotoxin blocks what
voltage gated KCh inhibiting repolarization -> prolonges AP -> prolonged Ca influx -> increased ACh release -> hyperexcitability and convulsive symptoms
malignant hyperthermia
rare, heritable condition (AD) that can be triggered by volatile anesthetics and some mm relaxor
what is the cause of MH
disorder of Ca regulation in skeletal mm -> uncontrolled release of Ca from SR -> rigidity, tachy, hyperventilation, and hyperthermia
what R is mutated in MH
RYR1 gene for ryanodine R (Ca release channel)
may also be linked to DHPR
where is the RyR located
SR membrane
where are the Dihydropyridine Rs located?
aka L-type CaCh
T-tubule membrane
what is the role of DHPR
voltage sensor
what is the role of Ca in the development of tension of skeletal mm
TnC + Ca -> removal of regulatory protein (tropomyosin) from actin -> x-bridge formation
number of x-bridges is directly proportional to tension production
what is required for mm relaxation to occur
removal of Ca form sarcoplasm which requires ATP and Ca pumps
what is the primary pump responsible for removing Ca from sarcoplasm in order for relaxation to occur
SR & ER Ca-ATPase (SERCA)
minor routes for Ca removal
Na-Ca exchanger in plasma membrane
calreticulin and calsequestrin
what enzyme catalyzes synthesis of ACh
choline acetyltransferase
choline + acetyl coenzyme A
what drives ACh uptake into the vesicle?
vesicular proton electrochemical gradient (+voltage and low pH inside)
