Chapter 9 The Muscular System

Standard 14 Classify the three categories of muscle fibers, differentiating between cells and tissue. Draw evidence from informational texts to explain the locations, behavioral properties, and functional roles unique to each category. Draw on knowledge of biological processes, such as the body’s conversion of ATP into energy, to illustrate phenomena such as muscle fatigue. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Introduction Skeletal muscles - movement in environment Smooth muscles - intestines, ureters, veins and arteries Cardiac muscle - pumps blood through heart and blood vessels 40% - 50% of body weight ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Types of Muscle Skeletal - voluntary, striated, multinucleated Smooth - involuntary, nonstriated and uninucleated Cardiac - involuntary, striated and uninucleated ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Anatomy of Skeletal or Striated Muscle

Skeletal/Striated Muscle Skeletal muscle cell surrounded by sarcolemma Fasciculi - bundles of fascicles Fascicles - individual bundles of muscle fibers ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Skeletal/Striated Muscle Perimysium - surrounds each fascicle Epimysium - covers the perimysium Fascia - covers the epimysium ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Physiology of Muscle Contraction

Muscle Contraction Motor unit - all muscle cells innervated by one motor neuron Muscle cell properties excitability conductivity contractility elasticity ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Neuroelectric Factors Na+ higher concentration outside muscle cell K+ higher concentration inside muscle cell Resting potential - charge outside positive and inside negative Electrical potential - rush of Na+ inside cell K+ moves outside cell attempting to balance ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Muscle Contraction Action potential calcium released troponin and tropomyosin action inhibited activated myosin links to action filaments ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Chemical Factors Myosin heads contain ATP ATP releases energy upon myosin/action link Energy released used to pull action Sodium - potassium pump pumps out sodium Resting potential restored ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Energy Sources ATP - energy source for muscle contraction ATP production glycolysis Krebs citric acid cycle electron transport Alternate sources - fatty acids and phosphocreatine ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Muscle Twitch Stimulus > latent period > contraction > relaxation Contraction strength depends on strength, speed and duration of stimulus weight of load temperature All-or-none law ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Muscle Tone State of partial contraction throughout whole muscle Maintains pressure on abdominal contents Helps maintain blood pressure Aids digestion Types isotonic, isometric ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Anatomy of Smooth Muscle Found in hollow structures Involuntary, uninucleated, nonstriated Arrangement (two layers) longitudinal (outer) circular (inner) ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Anatomy of Cardiac Muscle Autonomic nervous system control Involuntary, uninucleated, striated Intercalated disks - coordinate contraction Cardiac muscles - contract, relax and contract at 75/minute ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Naming and Actions of Skeletal Muscles Shape Origin and insertion Location Direction of fibers ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Naming and Actions of Skeletal Muscles Origin - more fixed attachment of muscle Insertion - movable attachment of muscle Tendons - attach muscle to bone Aponeurosis - wide flat tendon ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Naming and Actions of Skeletal Muscles Flexors - bend limb at a joint Extensor - straighten limb at a joint Abductors - move limb away from midline Adductors - bring limb toward midline Rotators - revolve limb around axis ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Naming and Actions of Skeletal Muscles Dorsiflexors - raise the foot Plantar flexors - lower the foot Supinators - turn palm upward Pronators - turn palm downward ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Naming and Actions of Skeletal Muscles Levators - raise a part of the body Depressors - lower a part of the body Prime movers - bring about an action Synergists - assist prime movers ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Animation The following animation illustrates how the accessory muscles assist with the breathing process. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.