Physiology 3120 Lecture : Excitation-contraction coupling - CV
Document Summary
Excitation-contraction coupling: ca required for contraction, but ca can be highly toxic in high amounts; ca compartments inside the cardiac cell (sarcoplasmic reticulum [sr]) ensure that a source of ca is close to the muscle, ca transport mechanisms. Ca channels (dihydropyridine [dhp] receptor) brings ca in; this is how ca enters during the plateau phase . Na/ca exchanger moves ca out (also capable of bringing ca in) using the concentration gradient of na (3 na in exchange for 1 ca) Ca pump (atpase) moves ca out; relatively small/accessory role. Ca pump (atpase) moves ca into sr; 1 mole of atp moves 2 moles of ca: phospholambin is an inhibitor of the pump; regulates ca pump. Ca channel (ryanodine receptor) lets ca out; ca is able to induce ca release through. Ca rushes in, and binds to ryanodine receptor. Ca released, and binds to troponin c in myofibrils, causing contraction.