Comprehensive Muscle Physiology: Cardiac Autorhythmicity, Contractile Cells, Calcium Signaling, Sarcoplasmic Reticulum, Ryanodine Receptors, Troponin-Independent Smooth Muscle, Calmodulin Activation, Myosin Light Chain Kinase, Skeletal Muscle Graded Contr

Comprehensive Muscle Physiology: Cardiac Autorhythmicity, Contractile Cells, Calcium Signaling, Sarcoplasmic Reticulum, Ryanodine Receptors, Troponin-Independent Smooth Muscle, Calmodulin Activation, Myosin Light Chain Kinase, Skeletal Muscle Graded Contractions, Fast Oxidative-Glycolytic Fibers, Slow Oxidative Fibers, Thermoregulation, Lever Mechanics, Dystrophin and Sarcolemma Integrity, Titin Elasticity, Alpha-Actinin Z-Disc Stability, Twitch Contractions, Relaxation Phase, ATP-Dependent Crossbridge Cycling, Pacemaker Cells, Mitochondrial Density, Lipid-Soluble and Insoluble Ca2+ Modulators Exam Questions Verified and Complete with A+ Graded Rationales Latest Updated 2026 What would occur if a lipid-insoluble Ca2+ channel agonist was applied to cardiac contractile cells? Ca2+ would enter into the cell independent of electrical stimulation and would stimulate Ca2+ release from the SR to produce more frequent cardiac muscle contractions. This fiber is intermediate in diameter, has lots of myoglobin, can contract quickly and has moderate resistance to fatigue. fast oxidative-glycolytic Which of the following muscle fibers are non-striated and involuntary? smooth In smooth muscle, what role does Ca2+ play in contraction? It binds to and activates Calmodulin, an activator of myosin light chain kinase, which in turn activates myosin. For myosin to detach from actin, it must bind to ATP Whole muscles can respond in a graded fashion by varying the number of motor units recruited BAPTA-AM, is a potent, lipid-soluble Ca2+ chelator (a molecule that binds up ions). If smooth muscle cells were exposed to BAPTA-AM, which molecule would likely be directly affected? calmodulin BAPTA-AM, is a potent, lipid-soluble Ca2+ chelator (a molecule that binds up ions). If smooth muscle cells were exposed to BAPTA-AM, what would be the effect on the smooth muscle cells? The cells would be unable to contract. Why don't smooth muscle cells have troponin? because smooth muscle uses a Ca2+-dependent signal transduction cascade to produce crossbridging Which of the following would be a consequence of the loss of excitability in a skeletal muscle? It would no longer be stimulated by normal means. Which of the following muscle types have a direct role in thermoregulation? skeletal Which of the following would be a consequence of the loss of contractility in a cardiac muscle? It would no longer be able to produce tension. A loss or mutation in which of the following molecules would lead to a disruption between the thin filaments and the sarcolemma? dystrophin A mutation in which of the following molecules could lead to a disruption between the Z-disc and the thin filament? alpha-actin