MCELLBI 32 Lecture Notes - Lecture 17: Atrioventricular Node, Cardiac Muscle, Action Potential

• School: Berkeley
• Department: Molecular And Cell Biology
• Course: MCELLBI 32
• Professor: Robin Ball

Document Summary

Mcb lecture #17: what initiates the heart beat, action potentials in the sa node, two types of contractile muscle, contractile muscle. Function: contract and provide force to move blood. Action potential is like neuronal action potential, except is longer because there is. Ca2+ influx through voltage-gates ca2+ channels that extends depolarization: autorhythmic cells pacemaker cells in sa node and av node, conduction fibers. Function: provide and conduct the rhythm of the heartbeat. Pacemakers initiate their own action potential without any input from neurons, lead to spontaneous action potentials. ***review of action potential in pacemaker cells and cardiac conduction: case study: abnormal ecg, a patient comes in complaining that he gets tired very quickly during exercise and he often feels dizzy. ***when a chamber depolarizes, cardiac muscle contraction (systole), pressure increase. ***when a chamber repolarizes, cardiac muscle relaxation (diastole), decreases pressure. Av open, semilunar valve closed, patria > pventricle, pventricle > parteries: ventricular pressure is less than aortic (artery) pressure.