L7 (L8 by uni) - E-C coupling Flashcards
which phase is the longest at rest of the cardiac cycle
passive filling
structure of cardiac myocytes
- branched
- striated
- has intercalated disks
what junctions does intercalated disks have
desmosomes - mechanical connection
gap junctions - electrical connection (ions pass through them~0
what is on thin filaments
actin
- tropomyosin
- troponin complex -
what consists id the troponin complex
TnC - binds to Ca
TnT - binds to tropomyosin
TnI- binds to actin to inhibit contraction
what does thick filaments have
myosin heavy chain - has bindind sites for actin and ATP
-myosin light chains -
what ion is
an absolute requirement for E-C coupling
Ca 2+ influx through Ly type Ca channels
why is there a pplateau phase during the propagation of action potential
- it elonagtes the AO due to Ca influx for E-C coupling
where are Ly type Ca channels
on the t=tubules on cardiac myocytes
what elese do you need to amplify the signal for more influx for Ca
SR Ca channels or RyRs
- this is called Ca induced Ca release
how does Ca induced Ca release work
L type Ca channels and Ryr have connections between them
- so when the Ltype channels open, they mechanically open RyR channels
- then the Ca released freom the SR
- contraction of the muscle occurs
how does the muscle relax
Ca needs to be dissocated from TnC
how to decrease intracellular Ca levels
- NCX1 - Na - Ca exchangers across the membrane
- PMCA ATPase - exchanger with Ca and H
-taking up Ca into SR by SERCA2a
taking up Ca by mitochondria
when does the contraction and relaxation happends
when the Na channels are inactivated
how to increase contractility by increasing intracellular Ca levels
- opens more Ltype channels and RyR
- inhibits NCX1 and PMCA
