Ventricular Ap Flashcards
Which 2 major ions are in highest concentration outside
Na and ca (ca inside but in sr)
What is phase 4 (start and end of ap)
Rmp at -80mv
Cell is polarised
What is the major channel in phase 4 rmp
Na/k ATPase
What is phase 0
Depolarisation via fast acting Na channels eg scn5a
What happens to allow Na in through fast acting Na channels
Electrical impulse from neighbour myocytes causes conformational change
What happens at around +40mv
Fast acting Na channels rapidly close via conformational change (h gate active)
What is phase 1
Early repolarisation
Transient outward current flow
via fast opening k channels (ones that encode ikr)
Is transient outward current flow in early repolarisation down conc gradient
Yes
Why does repolarisation stops fast after phase 1
Plateau phase phase 2 starts when ca enter cell
What type of ca channel allows entrance into cell in phase 2 plateau
L type (long type)
What does ca enterance allow
Excitation contraction coupling
Ca induced ca release via Ryanodine receptors on sr
Which phase is unique to ventricular heart muscle and why
Phase 2, ca not needed for others bc eg san cells don’t contract
Which channels causes uptake of ca back into sr
Ca ATPase
Serca channel
Other than serca, what else removes ca for heart relaxation (diastole)
Ncx
3 Na move in , 1 ca moves out via energy from Na gradient
What is phase 3
Rapid repolarisation
L type channel closes
Slow acting k channels open eg kcnq1
K leaves cell
(Shortly after restored by Na/k pump)!
