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Heart/skeletal differences. New slide. See 673. Cardiac Muscle Short cells Cells connected by desmosomes and gap junctions for strong connection and communication. Skeletal Muscle Long cells Cells independent of each other. Heart/skeletal differences. New slide. See 673.
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Heart/skeletal differences New slide See 673 • Cardiac Muscle • Short cells • Cells connected by desmosomes and gap junctions for strong connection and communication • Skeletal Muscle • Long cells • Cells independent of each other
Heart/skeletal differences New slide See 673 • Cardiac Muscle • 25%+ mitochondria by volume • Myofibrils branch and vary in size (striations less obvious) • Skeletal Muscle • 2% mitochondria by volume • Very regular myofibrils
Heart/skeletal differences New slide See 673 • Cardiac Muscle • fewer and larger T tubules. • No terminal cisternae– no triads • Skeletal Muscle • T tubules and cisternae result in triads
Heart/skeletal differences New slide See 673 • Cardiac Muscle • some cells fire on their own • Organ fires as whole • Skeletal Muscle • Each cell must be stimulated by nerve in order to fire • Motor units fire together
Heart/skeletal differences New slide See 675 • Cardiac Muscle • Longer contractile phase from single action potential • longer refractory period • Skeletal Muscle • Shorter contractile phase (from single action potential) • shorter refractory period
Heart/skeletal differences New slide See 675 • Cardiac Muscle • calcium comes mostly from SR (80%) with additional coming from extracellular space (“slow channels”) • Skeletal Muscle • Calcium comes from sarcoplasmic reticulum, with action potential.
Heart/skeletal differences New slide See 675 • Cardiac Muscle • anaerobic function quickly shuts down cell (see 675) • Skeletal Muscle • Able to function anaerobically
Heart/skeletal differences New slide See 675 • Cardiac Muscle • “leakage” of Na+ causes slow depolarization to some threshold which triggers calcium channels to open, causing rapid polarity change • Skeletal Muscle • Entry of Na+ causes depolarization and action potential This is about the “autorhythmic” cells