Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chap 30 – Muscle
Document related concepts
Transcript
Chapter 30 How Animals Move PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko MUSCLE CONTRACTION AND MOVEMENT © 2012 Parson Education, Inc. Muscle fiber Unit of muscle contraction Muscle fiber (cell) Nuclei Intercalated discs Nucleus Cardiac muscle* Junction between two cells Muscle fiber Nucleus Skeletal muscle Smooth muscle* *Under INVOLUNTARY control Muscle Muscle fibers = single muscle cell Several muscle fibers – have many nuclei Single muscle fiber (cell) Nuclei Plasma membrane Myofibril Light band Dark Light band band Z line Sarcomere Thick filaments (myosin) Thin filaments (actin) Z line Sarcomere Z line – Contains myofibrils Single muscle fiber (cell) Nuclei Plasma membrane Myofibrils = protein cables of overlapping Myofibril – thick filaments Light band Dark Light band band Z line – composed of the protein myosin and – thin filaments Sarcomere – composed of the protein actin. Sarcomeres = contractile unit of muscle fiber Light band – repeating groups of overlapping thick and thin filaments Dark Light band band Z line Sarcomere Thick filaments (myosin) Thin filaments (actin) Z line Sarcomere Z line Sarcomere contracts (shortens) when its thin filaments slide across its thick filaments Z Sarcomere Dark band Z Relaxed muscle Contracting muscle Fully contracted muscle Contracted sarcomere Detailed structure of thin filaments Actin associated with two other proteins: -Tropomyosin - troponin Motor Motor unit 1 unit 2 Spinal cord Nerve Motor neuron Motor neuron cell body axon Synaptic terminals Nuclei Muscle fibers (cells) Muscle Tendon Bone A motor neuron – carries an action potential (nervous signal) to a muscle cell, – initiates a muscle contraction by triggering release of Ca2+ from ER Motor neuron axon Mitochondrion Action potential Synaptic terminal T tubule Endoplasmic reticulum (ER) Ca2 released from ER Myofibril Plasma membrane Sarcomere Myosin-binding sites blocked Tropomyosin Actin Role of Ca in muscle contraction Ca2-binding sites Troponin complex Ca2 floods the cytoplasmic fluid Myosin-binding sites exposed Myosin-binding site Calcium ions bind to troponin, moving tropomyosin away from the myosinbinding sites on actin. Sliding Filament Model of Muscle Contraction: Sarcomere contracts (shortens) when its thin filaments slide across its Z thick filaments Sarcomere Dark band Z Relaxed muscle Contracting muscle Fully contracted muscle Contracted sarcomere A muscle contracts when thin filaments slide along thick filaments Thick filament Thin filaments Z line © 2012 Parson Education, Inc. Figure 30.9B_s2 Thick filament Thin filaments Z line Actin 1 Thin filament Thick filament ATP Myosin head (lowenergy configuration) Figure 30.9B_s3 Thick filament Thin filaments Z line Actin 1 Thin filament ATP Myosin head (lowenergy configuration) ADP P Myosin head (highenergy configuration) Thick filament 2 Figure 30.9B_s4 3 ADP P Cross-bridge Figure 30.9B_s5 3 ADP P Cross-bridge New position Thin filament of Z line moves toward center. ADP P 4 Myosin head (pivoting) Figure 30.9B_s6 3 ADP P Cross-bridge New position Thin filament of Z line moves toward center. ADP P 4 Myosin head (pivoting) 5 ATP Myosin head (low-energy) A muscle contracts when thin filaments slide along thick filaments ATP required to power myosin movement and RELEASE from actin Aerobic respiration supplies most of the energy for exercise Aerobic respiration – requires a constant supply of glucose and oxygen – provides most of the ATP used to power muscle movement during exercise. Lactic acid fermentation – can provide ATP faster than aerobic respiration but – is less efficient. © 2012 Parson Education, Inc. Figure 30.11 Supplying Fuel for High Performance Muscles can adapt to exercise by increasing the – levels of myoglobin, – number of mitochondria, and/or – number of capillaries going to muscles. © 2012 Parson Education, Inc. Table 30.12 Percentage of total muscle Figure 30.12 100 80 Slow Intermediate Fast 60 40 20 0 World- Average Average Middle- World- Extreme class couch active distance class endurance sprinter potato person runner marathon athlete runner
