Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dee Unglaub Silverthorn, Ph.D. H UMAN P HYSIOLOGY PowerPoint ® Lecture Slide Presentation by Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University AN INTEGRATED APPROACH T H I R D E D I T I O N Chapter 12 Muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings About this Chapter Muscle types What muscles do How muscles contract Contraction to locomotion Roles of smooth muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscles Contract! Generate motion Generate force Generate heat Support

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscular System Functions Body movement (Locomotion) Maintenance of posture Respiration Diaphragm and intercostal contractions Communication (Verbal and Facial) Constriction of organs and vessels Peristalsis of intestinal tract Vasoconstriction of b.v. and other structures (pupils) Heart beat Production of body heat (Thermogenesis)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Muscle Excitability: capacity of muscle to respond to a stimulus Contractility: ability of a muscle to shorten and generate pulling force Extensibility: muscle can be stretched back to its original length Elasticity: ability of muscle to recoil to original resting length after stretched

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Types Cardiac – heart Smooth – internal organs Skeletal – "voluntary" Attach to bone Move appendages Support body Antagonistic pairs Flexors Extensors

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Types of Muscle Skeletal Attached to bones Makes up 40% of body weight Responsible for locomotion, facial expressions, posture, respiratory movements, other types of body movement Voluntary in action; controlled by somatic motor neurons Smooth In the walls of hollow organs, blood vessels, eye, glands, uterus, skin Some functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regulating blood flow, In some locations, autorhythmic Controlled involuntarily by endocrine and autonomic nervous systems Cardiac Heart: major source of movement of blood Autorhythmic Controlled involuntarily by endocrine and autonomic nervous systems

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings S12-8 Categories of skeletal muscle actions Categories Actions Extensor Increases the angle at a joint Flexor Decreases the angle at a joint Abductor Moves limb away from midline of body Adductor Moves limb toward midline of body Levator Moves insertion upward Depressor Moves insertion downward Rotator Rotates a bone along its axis Sphincter Constricts an opening

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Connective Tissue Sheaths Connective Tissue of a Muscle Epimysium. Dense regular c.t. surrounding entire muscle Separates muscle from surrounding tissues and organs Connected to the deep fascia Perimysium. Collagen and elastic fibers surrounding a group of muscle fibers called a fascicle Contains b.v and nerves Endomysium. Loose connective tissue that surrounds individual muscle fibers Also contains b.v., nerves, and satellite cells (embryonic stem cells function in repair of muscle tissue Collagen fibers of all 3 layers come together at each end of muscle to form a tendon or aponeurosis.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Types Figure 12-1: Three types of muscles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Tissue Types

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings About 40% body mass Muscle fibers – cells Fascicle – bundle Motor unit Muscle sheath Attach to tendons (which attach to bone) Skeletal Muscle Anatomy

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Nerve and Blood Vessel Supply Motor neurons stimulate muscle fibers to contract Neuron axons branch so that each muscle fiber (muscle cell) is innervated Form a neuromuscular junction (= myoneural junction) Capillary beds surround muscle fibers Muscles require large amounts of energy Extensive vascular network delivers necessary oxygen and nutrients and carries away metabolic waste produced by muscle fibers

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Anatomy Figure 12-3a-1: ANATOMY SUMMARY: Skeletal Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Anatomy Figure 12-3a-2: ANATOMY SUMMARY: Skeletal Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multiple nuclei Sarcolemma T-tubules Sarcoplasmic reticulum Sarcoplasm Mitochondria Glycogen & ions Myofibrils Muscle Fiber Structure

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Fiber Structure Figure 12-3b: ANATOMY SUMMARY: Skeletal Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle Fiber Structure Figure 12-4: T-tubules and the sarcoplasmic reticulum

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Actin – "thin fibers" Tropomysin Troponin Myosin – "thick fibers" Titin – elastic anchor Nebulin – non-elastic Myofibrils: Site of Contraction

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Myofibrils: Site of Contraction Figure 12-3c-f: ANATOMY SUMMARY: Skeletal Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Z disks I band A band H Zone M line Titin Nebulin Sarcomere: Organization of Fibers Figure 12-5: The two- and three-dimensional organization of a sarcomere

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sarcomere: Organization of Fibers Figure 12-6: Titin and nebulin

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Contraction Sequence: Sliding Filament Theory Figure 12-9 (steps 1 & 2): The molecular basis of contraction

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Contraction Sequence: Sliding Filament Theory Figure 12-9 (steps 3 & 4): The molecular basis of contraction

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Contraction Sequence: Sliding Filament Theory Figure 12-9 (steps 5 & 6): The molecular basis of contraction

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Contraction: Mechanism Figure 12-11a: Excitation-contraction coupling

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Contraction: Mechanism Figure 12-11b: Excitation-contraction coupling

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings One Postulated Cause of Muscle Fatigue Stress responses in skeletal muscle during E-C coupling. Stress-induced RyR1 dysfunction can result in SR Ca 2+ leak, which potentially activates numerous Ca 2+ -dependent cellular damage mechanisms. AC, adenylate cyclase.

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Energy for Contraction: ATP & Phosphocreatine Aerobic Respiration Oxygen Glucose Fatty acids ATPs Anaerobic Respiration Fast but 2 ATP/glucose Phosphocreatine  ATPs

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Energy for Contraction: ATP & Phosphocreatine Figure 12-13: Phosphocreatine

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Central "Feeling" Lactic acid Peripheral Glycogen depletion Ca 2+ interference High P i levels ECF high K + ACh depletion Muscle Fatigue: Causes not well known Figure 12-14: Locations and possible causes of muscle fatigue

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rate 2-3 times faster SR uptake of Ca 2+ ATP splitting Anaerobic/Fatigue easily Power lifting Fast/delicate Sprint Fiber Contraction Speed: Fast Twitch

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fiber Contraction Speed: Fast Twitch Figure 12-15: Fast-twitch glycolytic and slow-twitch muscle fibers

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Oxidative Fast Twitch Intermediate speed Anaerobic & aerobic Slow Twitch: Aerobic, less fatigue More mitochondria More capillaries Myoglobin Endurance activities Postural muscles Fiber Contraction Speed: Oxidative Fast & Slow

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Coordinating the Fibers: Force of Contraction Figure 12-16: Length-tension relationships in contracting skeletal muscle Excitation and Twitch Length–Tension: more crossbridges: more tension

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Coordinating the Fibers: Summation to Tetanus Figure 12-17: Summation of contractions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Fusiform cells One nucleus per cell Nonstriated Involuntary Slow, wave-like contractions

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Cells are not striated Fibers smaller than those in skeletal muscle Spindle-shaped; single, central nucleus More actin than myosin No sarcomeres Not arranged as symmetrically as in skeletal muscle, thus NO striations. Caveolae: indentations in sarcolemma; May act like T tubules Dense bodies instead of Z disks Have noncontractile intermediate filaments

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Grouped into sheets in walls of hollow organs Longitudinal layer – muscle fibers run parallel to organ’s long axis Circular layer – muscle fibers run around circumference of the organ Both layers participate in peristalsis

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Is innervated by autonomic nervous system (ANS) Visceral or unitary smooth muscle Only a few muscle fibers innervated in each group Impulse spreads through gap junctions Whole sheet contracts as a unit Often autorhythmic Multiunit: Cells or groups of cells act as independent units Arrector pili of skin and iris of eye

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Cell

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Contraction: Mechanism

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Relaxation: Mechanism

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Contractile fibers are arranged in oblique bundles rather than in parallel sarcomeres

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Myosin of Smooth Muscle Different isoform than that found in skeletal muscle Smooth muscle myosin ATPase activity is much slower, contraction is longer Myosin light chain in the myosin head regulates contraction and relaxation

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Muscle Relatively little sarcoplasmic reticulum Lacks T-tubules Chemically linked to the cell membrane, rather than mechanically linked Ca +2 storage is supplemented by caveolae, small vesicles that cluster close to the cell membrane. Voltage/ligand gated Ca +2 channels

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Single-Unit Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Single-Unit Smooth Muscle Gap junctions Pacemaker cells with spontaneous depolarizations Innervation to few cells Tone = level of contraction without stimulation Increases/decreases in tension Graded Contractions No recruitment Vary intracellular calcium Stretch Reflex Relaxation in response to sudden or prolonged stretch

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multi-Unit Muscle

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Comparisons Among Skeletal, Smooth, and Cardiac Muscle