CHS 9-10 MUSCLES AND MUSCLE TISSUE

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1 CHS 9-10 MUSCLES AND MUSCLE TISSUE The muscular system provides for movement of the body and its parts (as muscles shorten), maintains posture, generates heat and stabilizes joints. The various types of muscles differ in the organization of their cells, location within the body, function and basis of activation. There are three types of muscle tissue in the human body: GENERAL CLASSIFICATION OF HUMAN MUSCLE TISSUES Cardiac Involuntary Intrinsic System Intercalated Discs Smooth Involuntary Calmodulin Types: Single-unit Visceral Multi-unit Skeletal (Striated) Voluntary Origin Insertion Calsequestrin CHARACTERISTICS OF SKELETAL MUSCLE TISSUE Prefixes such as myo-, sarco-, or mys- all refer to muscle tissue and/or muscles in general. Special terminology is used to designate the extreme specializations of skeletal muscle cells: Sarcolemma Sarcoplasm 44

2 Sarcoplasmic Reticulum T-tubules Calsequestrin Fibers Myofibrils Myofilaments Actin Troponin Tropomyosin Myosin Titin SARCOMERE STRUCTURE AND THE SLIDING FILAMENT THEORY OF MUSCLE CONTRACTION The structure of a sarcomere includes: Z-line I-band A-band Isotropic Anisotropic H-zone M-line CONNECTIVE TISSUES SUPPORTING SKELETAL MUSCLES Skeletal muscles can exert tremendous power because when they stretch, thousands of their fibers are bundled together by connective tissue. Therefore, they do not rip apart when they contract. There are two sets of CT wrappings for skeletal muscles: Fascia Superficial fascia 45

3 Deep Fascia Endomysium Perimysium Epimysium Subcutaneous (Visceral) Fascia NEURONS AND THE PROCESS OF MUSCLE CONTRACTION Neurons are cells of the NS that provide stimulation to help body cells/tissues/organs (such as muscles) get the energy they need to do their job. Neuron Cell Body Dendrites Axon Myelin Sheath Synaptic Vesicles Neurotransmitters Acetylcholine (ACh) Acetylcholinesterase AChE Neuromuscular Junction Motor Unit CLASSIFICATION OF TYPES OF MUSCLE FIBERS There are several types of muscle fibers, including slow and fast. Slow have a pink coloration (due to the presence of myoglobin) and fast have a white coloration. Human skeletal muscles include a mixture of slow and fast fiber types; therefore they look pink. Most skeletal muscle cells are primarily the fast fiber types. There are different amounts of each type of fiber in the various muscles of the body. 46

4 Myoglobin Fiber Types: Slow Oxidative (Type I) Fast Oxidative (Type II) Fast Glycolytic (Type II-B) ENERGY ACQUISITION FOR MUSCLE OPERATIONS A great deal of energy is used to power the muscles of the body. Energy is acquired from nutrients via the processes of cellular respiration and creatine phosphate production. The normal energy-releasing process occurs in the cytoplasm and mitochondria of a cell and is termed cell respiration. Cellular Respiration Aerobic overall Glycolysis TCA (Krebs Cycle) ETS/Cytochrome System Mitochondria Fermentation Pathway Sing: Mitochondrion Anaerobic overall Cori Cycle Creatine Phosphate Phosphocreatine PROCESS OF MUSCLE FATIGUE Fatigue is caused by excessive lactic acid production. Lactate (lactic acid) must be processed back into pyruvate (pyruvic acid) and shunted back into aerobic respiration. A change in ph caused by the lactic acid build-up affects AChE and stimulates a shunt process. ADJUSTING MUSCLE TENSION All or None Principle Threshold Stimulus Liminal Stimulus 47

5 Subliminal Twitch Treppe Tetanus Isotonic Isometric NAMING SKELETAL MUSCLES 1 Direction of muscle fibers Rectus Transverse Oblique. 2 Location of the muscle: See muscle distribution diagrams in text. 3- Size of the muscle: Maximus Longus Minimus Brevis 4 Number of origins: Biceps Triceps 48

6 5- Shape of the muscle: Rhomboid Serratus Platysma Deltoid Trapezius 6 The muscle s origin and insertion: Origin Insertion 7 The action caused by the muscle: Levator Flexor Extensor Abductor Adductor FUNCTIONAL CLASSIFICATION OF SKELETAL MUSCLES Prime mover Antagonist Synergist Fixator 49

7 DISORDERS/DISEASES Achilles tendonitis Charley horse Fibromyositis Hernia Inflammation of the Achilles (calcaneal) tendon caused by trauma such as micro tearing. Often caused by running (track or jogging). Muscle contusion. Trauma induced tearing of muscle with bleeding into the tissues (hematoma formation). A/k/a fibromyalgia. Inflammation of muscles and their CT s. Nonspecific symptoms. Protrusion of an organ through its body cavity wall. Muscular dystrophy Myalgia General term. Refers to a group of inherited muscle diseases that all cause muscle enlargement due to replacement of functional muscle tissue with non-contractile CT, such as adipose tissue. Duchenne form of MD is caused by lack of protein known as dystrophin. General muscle pain resulting from any type of disorder. Myasthenia gravis Myopathy Autoimmune disease involving muscle membrane acetylcholine (ACh) receptors. Inhibits communication between skeletal muscles and their nerves. General term for any disease of a muscle. Shin splints Pain due to irritation of tibialis anterior muscle. Spasm Involuntary twitch due to chemical imbalance. Results in inflammation. Strain Tennis elbow Tetanus Torticollis A/k/a pulled muscle. Due to excessive stretching and/or tearing of the muscle. Inflammation due to overuse. A/k/a lateral epicondylitis. a condition where the outer part of the elbow becomes painful and tender, usually as a result of a specific strain or overuse. Sustained muscle contraction. Can result from normal muscle function but also is term used to refer to Clostridium tetani infection (anaerobic) of skeletal muscle tissue. Twisting of the neck with chronic rotation and tilting of the head. Due to injury of sternocleidomastoid muscle on one side. A/k/a wryneck. Sometimes occurs during birth process. 50