KAAP221 Lecture Notes - Lecture 6: Cardiac Muscle, Skeletal Muscle, University Of Manchester

• School: University of Delaware
• Department: Kinesiology & Appl Physiology
• Course: KAAP221
• Professor: Shannon Lennon

Document Summary

Lecture 6: cardiac muscle cell contractions, comparison of muscle cell contractions, skeletal muscle. Ap relatively brief; twitch contraction short; twitches can summate and tetanus (sustained muscle contraction) can occur. Can have contractions happen one after the other; many that occur; twitches summate, sustained contraction (holding - static - a dumbbell in one place and sustaining the contraction) Refractory period is very brief: cardiac muscle. Ap long; contraction period long (~250 msec); tetanic contractions cannot occur. Cannot have another ap occur in the refractory period. Long absolute refractory period; relative refractory period is longer than in skeletal muscle. Differences in ionic composition of ic and ec fluids. Differences in permeability of pm to those ions: na and cl are predominantly outside of cell; k is predominantly inside of cell, 2 factors generate resting membrane potential, cardiac ap"s, 3 stages of cardiac ap, 1. Rapid depolarization - go from being very negative to positively charged; at threshold (~ -