HHD - CO

Question 1

Two main Ca2+ removal mechanisms

Answer 1

Ca-ATPase into SR (SERCA) and Na-Ca out of cell (NCX)

Question 2

3 x control points of CICR

Answer 2

1) Amount of Ca2+ entering the cell (ICa)
2) Sensitivity of RyRs to Ca2+
3) Amount of SR Ca2+ available to exit via RyRs

Question 3

Steady state

Answer 3

Ca2+ influx and efflux must be equal on each heartbeat

Question 4

Peak voltage for Ca2+ current

Answer 4

10mV, transient peak is similar but mirrored.

All calcium channels are open.

Question 5

Why bell-shaped?

Answer 5

Rising; membrane potential gets more positive so more and more Ca2+ channels open - increases positive charge more.
Falling; decrease in driving force as the inside gets more positive, therefore there is an increase in ICa.

Question 6

What if L-type Ca2+ channels are blocked?

Answer 6

Transient graph looks the same - therefore transient relies on SR release.