Physiology 3120 Lecture Notes - Lecture 2: Threshold Voltage, Spontaneous Generation, Myocyte

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Hore Neuro

Document Summary

Normal heart rate = 72 bpm (in vivo) Impulses normally originate in sinoatrial (sa) node located in the upper posterior wall of the right atrium. Most cardiac cells have the capability of self-excitation = can spontaneously produce ap. Many types of aps : slow response ap found in sa node fiber, slow depolarizing phase, fast response ap found in ventricular muscle fiber, fast depolarizing phase. Different cardiac cells use special ion channels to produce distinctive aps. In some cases, different cardiac cells use the same type of ion channel in different ways and at different times. Cardiac aps are a lot slower than neuronal aps time on x axis is in seconds whereas neuronal ap is in milliseconds. Ion channels and resulting current that"re responsible for aps in the heart along with their functional role. Some channels are voltage-gated while others are ligand (chemically) gated and some are both voltage and ligand gated.