BIOL 031 Lecture Notes - Lecture 9: Sinoatrial Node, Purkinje Fibers, Atrioventricular Node

• School: College of The Sequoias
• Department: Biology (BIOL)
• Course: BIOL 031
• Professor: trimble

Document Summary

Spread of excitation through the heart muscle. Auto rhythmicity do not need to think about it. Spontaneously depolarizing membrane potentials to generate action potentials. Sinoatrial node (sa) pacemaker of the heart; upper right atrium, ap travels through av node, higher beat frequency, conduction fires can conduct ap quickly. Atrioventricular node (av) rarely has a chance to fire an ap. Two channels that open = na and k = depolarization. Autorhythmic (in the absence of any nerve stimulus) Rapidly conduct action potentials initiated by pacemaker cells to myocardium. Ordinary muscle fibres, cv = 0. 4 meter/second. Stable resting potential, ap fires, then stable resting pot, then ap. Membrane potential is stable until a stimulus causes it to fire. Due to opening of funny channels, cause depolarization to: Open fast t-type ca2+ channels to threshold. L-type calcium channels cause rapid upswing of membrane potential.