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Muscular System

Explore the functions, properties, and physiology of the muscular system, including muscle types, contraction processes, energy sources, and age-related changes. Learn about muscle twitch, fatigue, hypertrophy, and atrophy.

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Muscular System

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  1. Muscular System Sports Training and Physiology Kociuba http://kidshealth.org/PageManager.jsp?lic=1&article_set=59302&cat_id=20607

  2. Muscular System - Objectives • List the major functions of muscles • Describe 4 major properties of muscles • Compare and contrast the 3 different types of muscles • Explain the sliding filament theory • Define a muscle twitch and it’s 3 phases • Define the different types of muscle contractions

  3. Muscular System – Objectives 2 • Name and compare the types of skeletal muscle fibers • Discuss the causes of fatigue during exercise • Explain how fibers obtain energy • Discuss causes of hypertrophy and atrophy • Discuss age related changes in skeletal muscle

  4. Functions of the Muscular System • Body Movement • Maintenance of posture • Respiration • Production of body heat • Communication • Constriction of organs and vessels • Heartbeat

  5. Contractility The ability to shorten forcefully Excitability Ability to respond to a stimulus Extensibility Ability of a muscle to be stretched beyond it’s normal resting length Elasticity Ability of a muscle to recoil to it’s original shape after it has been stretched Functional Properties of Muscles

  6. Connective tissue coverings of a Muscle

  7. Anatomy of the Skeletal Muscle • Filaments found in the myofibrils • Actin • Myosin • Together they make sarcomeres that make up… • Myofibrils: threadlike structure that extends from one end of the muscle to the other

  8. How do muscles contract? Sliding Filament Model

  9. Muscle Twitch:contraction and relaxation to a stimuli that causes action potential in one or more muscle fibers • Lag/Latent phase: time it takes to stimulate the motor neuron to cause the muscle to contract • Contraction phase: time during which a contraction occurs • Relaxation phase: time in which relaxation occurs

  10. Isometric: Length doesn’t change, but tension increases during the contraction phase Muscle Tone: Constant tension produced over long periods of time Isotonic: Amount of tension is constant but length changes Concentric: shortening a muscle Eccentric: lengthening a muscle Types of Muscle Contractions

  11. How do the muscles get energy to contract? • ATP is the immediate source of energy used by the muscles • ATP must be used continuously in order to keep a muscle contracted • 3 ways body makes ATP production for the muscles • Creatine phosphate • Anaerobic glycolysis • Aerobic respiration

  12. Creatine Phosphate: Energy Source is creatine phosphate Creates 1 ATP Oxygen is NOT required Duration of energy is 10 seconds Anaerobic Glycolysis: Energy Source is glucose Creates 2 ATP Oxygen is NOT required Duration of energy is up to 3 minutes ATP Production happens in the mitochondria

  13. ATP Production happens in the mitochondria • Aerobic Respiration • Energy Source is glucose, lactic acid, fatty acids, amino acids • Oxygen is required • Creates up to 36 ATP • Duration of energy is hours!!!

  14. Exercise and Fatigue • Fatigue: decreased capacity to do work and the reduced efficiency of performance to do work • Psychologic fatigue: most common type. Individual perceives that they can not use the muscle anymore • Muscular fatigue: the reduced or absent ability of muscle fibers to respond to stimuli

  15. Hypertrophy Muscle size increases Slow and fast twitch muscle fibers increase depending upon what exercises you do Atrophy Decrease in muscle size Disuse Atrophy Denervation Atrophy Hypertrophy and Atrophy

  16. Age related changes in skeletal muscle • Loss of muscle fibers as early as the age of 25 • By 80 50% of muscle mass is gone • Fast-twitch muscle fibers deteriorate faster than slow-twitch

  17. Gross Anatomy Generalized Groupings of the Muscles of the Body *We will go over in depth starting next week with anatomy Mondays and Injury/Rehab Fridays

  18. The Muscular System

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