8. Cardiac calcium induced calcium release

1. A cardiac myocyte action potential travels along the _ and into the _.

sarcolemma, T-tubules

2. Depolarization opens _ channels in the _ membrane. Calcium also enters the cell from the _.

voltage-gated calcium, T-tubule, extracellular fluid

3. The incoming calcium activates _ on the _, causing additional calcium release. This is calcium-induced calcium release and produces a local calcium spark

ryanodine receptors, sarcoplasmic reticulum,

4. _ binds _. _ moves away from myosin-binding sites on actin, allowing cross-bridge cycling.

Cytosolic calcium, troponin, Tropomyosin

5. Relaxation requires _. Calcium is pumped back into the sarcoplasmic reticulum and is also transported out of the cell, including through _.

calcium removal, sodium-calcium exchange

Trigger for SR calcium release in skeletal muscle vs cardiac muscle

DHP receptor mechanically activates ryanodine receptor, extracellular calcium enters through voltage-gated calcium channels and activates ryanodine receptor

How does a cardiac muscle relax?

Ca2+-ATPase plus extrusion of calcium from the cell via secondary active transport with sodium