ELAINE N. MARIEB EIGHTH EDITION 6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY PART A The Muscular System

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings I. Introduction 1) Muscle is from the Latin mus meaning little mouse 2) The essential function of muscle is contraction (unique to muscle) 3) This is responsible for essentially all body movement

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings II. Muscle Tissues 1) Types: a) Skeletal, cardiac and smooth b) Similarities: 1. Skeletal and smooth are elongated cells (Muscle fibers) 2. Myofilaments: cause muscle to shorten 2) Skeletal muscle: a) Skeletal muscle fibers are cigar-shaped, multinucleate cells and the largest of muscle fibers

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings b) Also called striated (striped) and voluntary (controlled) c) Skeletal muscle contracts rapidly but tires easily d) Parts of a muscle: (Fig. 6.1) endomysium, perimysium, fascicle, muscle fiber e) The epimysium blend into the tendons or aponeuroses, which attach muscles

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Figure 6.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 3) Smooth muscle a) No striations, involuntary, spindle-shaped and single nucleus b) Found in walls of visceral organs and blood vessels c) Called visceral, non-striated and involuntary d) Smooth muscle contracts and tires slowly

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Smooth Cardiac

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 4) Cardiac Muscle: a) Found only in the heart b) Striated and involuntary c) Arranged in spiral bundles, contracts to make chambers smaller d) Contracts rhythmically 5) Functions a) Movement: b) Maintaining posture c) Stabilizing joints d) Generate heat

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings III. Microscopic Anatomy 1) Sarcolemma: 2) Myofibrils: Figure 6.3a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 3) Bands and zones: (Figure 6.3 B) a) Light (isotropic or I) band: b) Dark (anisotropic or A) band: c) H zone d) Z disc (line) e) M line f) Sarcomere:

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings sarcomere

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 4) Myofilaments a) Proteins forming the myofibrils b) Thick (myosin) filaments: bundles of myosin protein c) Thin (actin) filaments: bundles of actin protein d) Myosin bridges connect filaments during contraction e) During contraction the actin filaments slide together

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 5) Sarcoplasmic reticulum (SR) stores calcium to be released during contractions

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings IV. Skeletal Muscle Activity 1) Two characteristics that allow muscles to work a) Irritability: ability to receive and respond to stimuli b) Contractility: ability to shorten forcible 2) Nerve stimulation (chapter 7) a) Motor unit:

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nerve Stimulus to Muscles Figure 6.4a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings b) Neuromuscular junction: c) Acetylcholine: the neurotransmitter carrying the impulse across the synapse d) The acetylcholine causes a chemical change called an action potential, which starts the contraction

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nerve Stimulus to Muscles Figure 6.5b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 3) Sliding filament theory: a) Action potential causes the SR to release calcium b) Calcium ions allows the myosin bridges to attach c) Myosin heads attach to binding sites on actin d) These pull the actin toward the center of the sarcomere

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Sliding Filament Theory Figure 6.8

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 4) Skeletal muscle contraction a) All or None law: muscle cells will contract completely or not at all b) Graded response: Muscles can contract at varying degrees c) Types of contractions 1. Twitch: single, brief jerky contraction 2. Complete Tetanus: a smooth contraction, no individual stimulation seen

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

3. Incomplete Tetanus: not smooth, individual contractions can be seen d) Maximal stimulus: point where more stimuli cannot make a stronger contraction 5) Energy for contraction a) Muscles store limited supplies of ATP (4-6 seconds) b) ATP is the only energy source for muscle activity

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings c) Three pathways to regenerate ATP 1. Direct phosphoryolation by creatine 2. Aerobic respiration 3. Glycolysis (anaerobic) and lactic acid formation 6) Muscle fatigue: a) lactic acid builds up, causing fatigue and soreness

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy for Muscle Contraction Figure 6.10b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings b) Fatigue: c) Oxygen debt: The oxygen needed to break down the lactic acid and complete cellular respiration 7) Isotonic: Contraction with same tension, but varying length (most movements)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 8) Isometric: Contraction with same length, but varying tension (posture, holding an object) 9) Tone: 10) Effects of exercise: a) Aerobic training: Increases blood supply, mitochondria & oxygen stored b) Resistance: Increases the number of contractile filaments End of 6-I test Start 6-II test

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings V. Muscle movement, types and names 1) Basic understandings about gross muscle activity: Golden rules a) With a few exceptions, all muscles cross at least one joint b) Typically, the bulk of the muscle lies proximal to the joint c) All muscles have at least 2 attachments d) Muscle can only pull, never push e) During contraction, the muscle insertion moves toward the origin

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

2) Points of attachment: a) Origin: the immovable or less movable end b) Insertion: the movable end 3) Common types of body movements: a) Flexion: Ends move together b) Extension: ends move apart c) Rotation: move around its axis d) Abduction: move limb away from the midline

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings e) Adduction: move limb toward the midline f) Circumduction: combination of movements forming a cone shape g) Inversion: turn sole medially h) Eversion: turn sole laterally i) Supination: rotate palm up j) Pronation: rotate palm down 4) Muscle names based on how they act a) Prime mover; major responsibility for a movement

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Body Movements Figure 6.13a–c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings b) Antagonist: muscle that acts in opposition c) Synergist: Help prime movers by producing the same movement d) Fixator: Hold a bone still or stabilizes the origin 5) Muscles can also be named by: a) Direction of the fibers b) Relative size c) Location of muscle

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings d) Number of origins e) Location of the origin & insertion f) Shape of muscle g) Action of muscle 6) Arrangement of fascicles (not on test): a) Circular b) Convergent c) Parallel d) Fusiform e) Pennate

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 7) Major muscle groups: Page (fig. 6.21& 6.22 Page 210 & 212) Origin, insertion action Table 6.3 page 211 & 213: We will study these on the cat

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Superficial Muscles: Anterior Figure 6.21

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Superficial Muscles: Posterior Figure 6.22

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings VI. Disorders: 1) Atrophy: wasting away of muscle from lack of stimulus 2) Muscular dystrophy: Group of inherited muscle destroying diseases that affect specific muscle groups (Duchenne’s is the most common and found in males only) 3) Myasthenia gravis: Drooping upper eyelids, difficulty swallowing and talking, general muscle weakness and fatigue. Involves shortage of acetylcholine receptors