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5/24/2017 Title: Anat & Phys 11/30/06 Objectives: To learn about the physiology of muscles. Class Topics • Review questions • Review contraction • Notes – – – – Relaxation Energy sources Isometric and isotonic contractions Contraction graphs Do, or do not do. There is no ‘try’. Yoda Wednesday, May 24, 2017 4:29 AM Page: 1 5/24/2017 Class Assignments What • • • • Read 197-212 Muscle Physiology quiz Contraction assignment Muscle physiology test By When 12/4/06 12/4/06 12/4/06 12/8/06 • Due this class period • Due next class period • Due in the future Page: 2 5/24/2017 Review 1. Sketch a myofibril – Label A band, I band, Z line, H zone, sarcomere, actin, myosin 2. What is the purpose for nuclei in the muscle cell? 3. What is the purpose for mitochondria in the muscle cell? 4. What connective tissue covering is found surrounding each fascicle? 5. What are three proteins are found in the “thin filament”? 6. What is a 1:10 ratio of motor neurons to muscle cells used for? What muscles? Page: 3 5/24/2017 Muscle physiology quiz • Topics – – – – – – Organelles All or none principle Myofibril anatomy Neuromuscular junction Connective tissue coverings Innervation ratios Page: 4 5/24/2017 Contraction step by step 1 Stimulation - acetylcholine released from motor neuron 2 Muscle fiber stimulation by acetylcholine & calcium ions are released from the sarcoplasmic reticulum 3 Calcium ions bind to troponin molecule 4 Troponin molecules change shape causing tropomyosin to rotate and expose active sites on the actin molecule Page: 5 5/24/2017 Contraction step by step 5 Cross bridges form between actin (active sites) and myosin filaments (globular proteins) 6 Actin filaments slide along myosin filaments (ATP used) due to a swivel action of myosin globular protein 7 Muscle fiber shortens as contraction occurs Wisconsin Online - animation Texas A&M University - animation Page: 6 5/24/2017 Relaxation 1 Acetylcholine decomposes and muscle fiber is no longer stimulated 2 Calcium ions are Actively TransPorted into sarcoplasmic reticulum 3 Cross bridges between actin and myosin are broken – troponin is no longer activated and it (and tropomyosin) rotates back into resting position over actin active sites Page: 7 5/24/2017 Relaxation (cont.) 4 Actin and myosin slide apart 5 Muscle fiber lengthens and resting state is reestablished Page: 8 5/24/2017 Pattern Puzzle • Put the paragraph on contraction back together Page: 9 5/24/2017 From: http://biomedia.bio.purdue.edu/GenBioLM/ GBMuscle/html/myofilaments.html Page: 10 5/24/2017 Assignment • In a series (at least 7) of pictures, draw a representation of contraction and relaxation. • Include a written basic overview of what is occurring in each step. • 10 pts. “Don’t tell people how to do things. Tell them what to do and let them surprise you with their results.” George Patton Page: 11 5/24/2017 Energy Sources for Contraction 1 ATP - found on each globular protein of myosin - 1 or 2 contractions 2 Creatine phosphate - 25 secs. changes ADP into ATP so the body can use it for energy 3 Other sources Page: 12 5/24/2017 Other Sources of NRG • Cellular respiration - using stored glucose and oxygen to form ATP – very efficient • Anaerobic Respiration – no oxygen – changes glucose to pyruvic acid and then to lactic acid - discomfort in muscles – inefficient energy source Page: 13 5/24/2017 From: http://www.nismat.org/physcor/energy_supply.html Page: 14 5/24/2017 Page: 15 5/24/2017 Anaerobic Respiration • Oxygen debt – oxygen goes toward decomposition of lactic acid - not respiration • Muscle fatigue – too much lactic acid - low pH - no contraction • Muscle cramp – muscle contracts but doesn’t relax – not enough ATP to move calcium ions back into SR Page: 16 5/24/2017 Muscle Tone • Sustained contraction occurring in muscle fibers at all times - resting muscle • Used for posture, body positioning, reflexes, and keep body firm • Lost when a person passes out – dead weight Page: 17 5/24/2017 Athletes • Higher tolerance to lactic acid • more capillaries in muscles • More muscle tone Page: 18 5/24/2017 Contraction types • Tetanic contractions – sustained contraction produced by rapid sequence of stimuli • Types of tetanus – 1. Isotonic – 2. Isometric Page: 19 5/24/2017 Isotonic • Produces movement as the muscle pulls the bone toward a stationary structure • ex. Bicep curl • All movements! Page: 20 5/24/2017 Isometric • Produces muscle tensions, but the muscle does not shorten • No body movement • ex. Pushing an immovable object Page: 21 5/24/2017 Twitch Page: 22 5/24/2017 Page: 23 5/24/2017 Muscle Types HO “Muscle, Genes, and Athletic Performance” • Slow twitch – Type I • Fast twitch – Type IIe – Type IIx Page: 24