.
Depolarization from a neighboring cell spread through connexon channels
Norepinephrine binding to α1-adrenergic receptors
Acetylcholine binding to nicotinic acetylcholine receptors
The movement of a bolus of food through the small intestine
Calmodulin
Troponin
Tropomyosin
Actin
Myosin light chains
Ca2+ influx from extracellular stores through voltage-activated Ca2+ channels
Ca2+ influx from the sarcoplasmic reticulum through IP3 receptors
Ca2+ influx from extracellular stores through ryanodine receptors
Ca2+ influx from extracellular stores through ligand-gated Ca2+ channels
Ca2+ influx through IP3 receptors, cross-bridge cycling, Ca-calmodulin activation of MLCK, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger
Ca2+ influx through RyR in the SR, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK, cross-bridge cycling
Ca2+ influx through L-type Ca2+ channels, Ca2+ activated Ca2+ release from RyR in the SR, Ca-calmodulin activation of MLCK, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger
Ca2+ influx through store-operated Ca2+ sensitive channels, cross-bridge cycling, Ca2+ removal from SR by SERCA, PMCA, and Na/Ca exchanger, Ca-calmodulin activation of MLCK
The source of activator calcium
The role of calcium in initiating contraction
The mechanism of force generation
The source of energy used during contraction
The nature of the contractile proteins
Calmodulin
Myosin light chains
Troponin
Tropomyosin
Protein kinase A
Calmodulin
Protein kinase A
Myosin light chain kinase
Myosin light chain phosphatase
Phospholipase C
Actomyosin ATPase
Bind to calcium ions to initiate excitation-contraction coupling
Phosphorylate cross-bridges, thus driving them to bind with the thin filament
Split ATP to provide the energy for the power stroke of the cross-bridge cycle
Dephosphorylate myosin light-chains of the cross-bridge, thus relaxing the muscle
Pump calcium from the cytosol back into the sarcoplasmic reticulum
Single-unit muscle contraction speed is slow, while multiunit is fast
Single-unit muscle has T-tubules, while multiunit does not
Single-unit muscles are not innervated by autonomic nerves
Single-unit muscle produces action potentials spontaneously that spreads to neighboring cells, while multiunit does not
Calmodulin
Protein kinase A
Myosin light chain kinase
Phospholipase C
Actomyosin ATPase
Thick and thin filaments arranged in sarcomeres
Troponin
Elevation of intracellular [Ca2+] for excitation-contraction coupling
Spontaneous depolarization of the membrane potential
High degree of electrical coupling between cells