Cardiac Muscle Contractions

Cardiac Muscle Contractions CARDIAC MUSCLE CONTRACTIONS Cardiac muscle contra  ction initiated by Ca2+ Mechanism of contraction: Increase in cytoplasmic/sarcoplasmic Ca2+—-> Causes contraction. Steps: On action potential development, ↓ Ca2+ influxes within cardiac cell. Via L-type Ca2+ channels in sarcolemma. ↓ Influx triggers Ca2+ release from sarcoplasmic reticulum to sarcoplasm. Via ryanodine receptors. ↓ Increases intracellular Ca2+ ↓ Causing cardiac muscle contraction. Mechanism during relaxation: Decreased cytoplasmic/sarcoplasmic Ca2+ –> Cardiac […]