BPK 305 Lecture Notes - Lecture 5: Hcn Channel, Sympathetic Nervous System, Action Potential

• School: Simon Fraser University
• Department: Biomedical Physio & Kines
• Course: BPK 305
• Professor: Damon Poburko

Document Summary

Lecture 5 initiation of the cardiac action potential. Propagation of the ap: 2) cell a gets just enough depolarization to create an ap, 3) cell b begins ap before cell a has completed its ap, 4) a lower threshold is needed to get ap. Pacemaker channel: structure like a k+ channel, a non-selective cation channel, and gated by camp. Named the hcn channel -> hyperpolarization-activated cyclic nucleotide gated channel: ***know what hcn means to define it on exam before using hcn. Aka funny current -> if: pathway sa node -> left/right atria -> bundle of his -> bundle branches. 2: 1) slower upstroke velocity, no na+ channels, depolarized by ica(cav1. 2, 2) reduced plateau duration. Ica inactivation after upstroke: 3) diastolic depolarization, due to pacemaking hcn channel. If hcn channels are more active, will reach threshold faster (or less active, will reach threshold slower: will cause heart to beat faster or slower, 4) higher resting potential, lack ik1 important for rmp.