BILD2_Lecture_3_1_12

BILD2_Lecture_3_1_12 - Figure 40.5ca Figure 50.UN01...

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Unformatted text preview: Figure 40.5ca Figure 50.UN01 Sarcomere Muscle Tissue Skeletal muscle Relaxed muscle Nuclei Muscle fiber Sarcomere 100 µm Contracting muscle Smooth muscle Cardiac muscle Thin filament Fully contracted muscle Nucleus Muscle fibers 25 µm Intercalated disk Nucleus 50 µm Figure 50.28a-5 Thick filament Contracted sarcomere Figure 50.26 Muscle 1 Thin filament Myosin head (lowenergy configuration) ATP ATP Bundle of muscle fibers 2 Thick filament 5 Thin filament moves toward center of sarcomere. Nuclei Single muscle fiber (cell) Myosinbinding sites Actin Plasma membrane Myofibril Z lines ADP Low-energy configuration Pi High-energy configuration Sarcomere ADP ADP Pi 4 Pi Cross-bridge 3 Thick filaments (myosin) Thin filaments (actin) TEM Z line M line Sarcomere 0.5 µm Z line Figure 50.27 Figure 50.29 Ca2+-binding sites Tropomyosin Actin Troponin complex Sarcomere Z 0.5 µm Z M Relaxed muscle (a) Myosin-binding sites blocked C a2+ Contracting muscle Myosinbinding site Fully contracted muscle Contracted sarcomere (b) Myosin-binding sites exposed Figure 50.30 Synaptic terminal Figure 50.31 Axon of motor neuron T tubule Sarcoplasmic reticulum (SR) Spinal cord Motor unit 1 Synaptic terminals Mitochondrion Myofibril Plasma membrane of muscle fiber Synaptic terminal of motor neuron T tubule Synaptic cleft Nerve Ca2+ released from SR Sarcomere 1 2 Plasma membrane Sarcoplasmic reticulum (SR) ACh Motor unit 2 Motor neuron cell body Motor neuron axon 3 C a2+ Ca2+ pump ATP 6 4 CYTOSOL Muscle C a2+ 7 Muscle fibers 5 Tendon Figure 50.32 Summation of two twitches Single twitch Action potential Pair of action potentials Circular Longitudinal Circular muscle relaxed muscle muscle contracted relaxed (extended) Series of action potentials at high frequency Longitudinal muscle contracted Figure 50.34 Biceps Bristles Head end Grasshopper tibia (external skeleton) Human forearm (internal skeleton) Flexion Figure 50.35 Time 1 Extensor muscle Flexor muscle Triceps Head end 2 Head end Biceps Extension Tension Tetanus When an organism dies, its muscles remain in a contracted state termed rigor mortis for a brief period of time. Which of the following most directly contributes to this phenomenon? A.  no input from the brain B.  no calcium to bind to troponin C.  no oxygen supplied to muscle D.  no ATP to break bonds between the thick and thin filaments E.  no energy for the synthesis of actin and myosin Triceps Extensor muscle Flexor muscle 3 Key Contracting muscle Relaxing muscle ...
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This note was uploaded on 04/05/2012 for the course BILD 2 taught by Professor Schroeder during the Winter '08 term at UCSD.

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