BMSC 207 Post Midterm Exam Questions and Correct Answers

Function of all musclesto generate force and movement Skeletal muscles- voluntary (somatic neurons) - striated - Multi-nucleated - insertion is more distal - antagonistic muscle groups = flexor-extensor pairs - 40% of body weight Cardiac Muscle- Primarily involuntary - striated and uninucleated - spontaneous electrical activity - altered by autonimc NS and hormones - intercalated disks that connects them - desmosomes (mechanical link) - gap junctions (electronical link) - larger but less T-Tubules Smooth musclesprimarily involuntary, autonomic control, spontaneous - controlled by hormones, paracrines or autocrines - mechanical movement of digestive tract, urinary tract, reproductive tract, blood vessels, airways Muscle terminology from big to littleTendon --> skeletal muscle --> fascicles --> muscle fiber --> myofibril --> myofilaments (actin + myosin) F-actinbackbone of thin filament (thin) - double helix strand of G-actin - contains binding site for Myosin Tropomyosin- dimer alpha helix that coil around eachother, coil coil - sit in grooves made by actin to stop myosin binding Troponin complexheterotrimer - troponin T: binds to tropomyosin - Troponin C: Ca2+ binding site - Troponin I: when resting binds to actin inhibiting contraction Thick Filamentmyosin bundles - myosin head contains actin binding site and ATP binding site