6: Excitation contraction coupling Flashcards
Trigger for Ca release
Ca influx
Where is Ca released from
Sarcoplasmic reticulum
What does Ca do to actin filament
Exposes binding site
What happens when external Ca enters the cell
Trigger myocardial force production
What terminates Ca influx
repolarization
What causes relaxation
Phosphorylation of phospholamban
What inhibits further Ca release
Calmodulin
What does unphosphorylated phospholamban do
inhibit Ca/ATPase pump
3 mechanisms for Ca movement
- Na-Ca exchanger
- Ca sequester pump (into Sarcoplasmic ret)
- Ca is bound by calreticulin and calsequestrin
How is intracellular Ca released
Graded
The more intracellular Ca, the greater the contractile force
What is the effect of B-1 activation on myocardial cells
Increases Ca opening
What is the increase in cAMP stimulated by
Sympathetic nervous system
What effect does an decrease in Na outside of the cell have on intracellular Ca
Increase
What effect does an increase in Na inside of the cell have on Ca
Increase
What does digialis do
Inhibit the Na/K pump
Less Na pumped out of cell
Increases contractility
Slows heart rate
