The Muscular System Chapter 9

I. Introduction  All movements require ________ (Chemical energy causes contraction)  Muscles: Move fluids such as _____ & ______ Produce heat which warms the body  Three types of muscle in the body are _______, _______, and ______

 _______ Muscle __________ muscles lining the organs (stomach, bladder, uterus, and blood vessels) __________ – (wave like contractions) moves substances through these (smooth) muscles ________ to contract and relax, but are _________ to fatigue Types

Types cont…  Cardiac ___________ muscle of the ______ Does _____ fatigue  Skeletal __________ muscle used for movement that are _______ to bones  The rest of this chapter will mainly focus on skeletal muscle

II. Structure of Skeletal Muscle  Each muscle is an _______ All are comprised of skeletal muscle tissue, connective tissues, nervous tissues, and blood

Structure cont…  Connective Tissue Coverings Layers of ______ surround and separate each muscle  Extends beyond the ends of the muscle WHY?  Gives rise to ______ that are fused to the _______ of the skeletal system (bones)

Structure cont… Around each whole muscle is the __________ The ___________ surrounds individual bundles (_________) within each muscle Each muscle cell (_____) is covered by an ____________

Structure cont… Within muscle fibers are many cylindrical tubes called _____________  contain _____ and _____ filaments (striations) ______ – made of the protein Myosin ______ – made of the protein Actin

STUDY ANALOGY Take 100 pencils (muscle fibers) -Wrap each pencil in tissue paper (endomysium) -Take 100 pencils in a bundle (a fascicle) and wrap them in paper (perimysium) -Then take all the bundles and wrap them in gift wrap (epimysium) -Wrap all of it up in brown paper (Fascia)

III. Muscles & The Nervous System  ______________ – site where a motor _______ and ______ ______ meet End of muscle fiber forms a motor end plate Motor neuron stores _______________ (chemicals)

 Motor Units A motor _______ and the ______ fiber it controls When stimulated to do so, the muscle fiber of the motor unit contract all at once (___________________) Muscles & Nervous cont…

IV. Skeletal Muscle Contraction The pulling of a muscle against its attachments  _______(energy) is needed from ___________________  The ______________, _______________, is released at the neuromuscular junction

Contraction cont…  _________ (Ca) ions are released into the muscle fibers  ______ and _______ slide together

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V. Skeletal Muscle Relaxation The lengthening and relaxing of a muscle from its attachments  ___________ is decomposed  Calcium ions _______ muscle fibers  ______ and ________ slide apart

Major Skeletal Muscles 9-31

Major Skeletal Muscles 9-32

VI. Skeletal Muscles of the Human Body  _______ – immovable end of a muscle  _______ – moveable end of the muscle _________ – always occurs to move point of insertions to its point of origin

Muscles cont…  Of a group of muscles, the one doing the majority of the work is the ______________  Helper muscles are called _________  Opposing muscles are called __________

Muscles cont…  Face _________ – lifts eyebrows ___________ ____ – moves lips _____________ – “Smile” muscle, lifts cheeks ___________ _____ – Moves skin around the eyes  Neck __________________ – Turns neck/head

Muscles cont…  Trunk Trapezius Pectoralis Major Pectoralis Minor Serratus anterior Intercostal Muscles Rectus Abdominis External Abdominal Obliques Latissimus Dorsi

Muscles cont…  Upper Extremities Deltoid Biceps Brachii Triceps Brachii

Muscles cont…  Lower Extremities Upper leg: Gluteus medius & maximus Sartorius Gracilis Rectus Femoris Vastus medialis, intermediate and lateralis Biceps femoris Lower leg: Tibialis anterior Soleus Gastrocnemius

VII. Oxygen Debt  During rest or moderate activity, there is enough oxygen to support ________ respiration  Oxygen _____________ develop during strenuous exercise  __________ acid (feeling of pain or muscle burning) builds up as an end product of anaerobic respiration  “Repaying” oxygen debt may take ____________.

VIII. Muscle Fatigue  Muscle losses its ability to ________ during strenuous exercise, from accumulation of ______ acid in the muscle.  _______ acid prevents muscle from contracting  A ____________ occurs due to a lack of ______ required to get rid of the ___________ so muscle fibers can ________

Fatigue cont…  Other causes of muscle fatigue....

IX. Muscle Function  _____________ is achieved by sustained contraction within a muscle, and is needed for normal posture

Function cont…  Slow Fibers Muscle fibers that are __________ to fatigue Use causes them to develop more _____________ (running, swimming, etc.)

Function cont…  Fast Fibers Forceful exercise (___________) causes muscles to ________ New ____ and ______ develop _______ of muscle fibers increase Entire muscle enlarges (_____________________________!)

Function cont…  Use/Disuse Muscular ___________  Decrease in ____ and ________ of muscles due to disuse (accidents, etc.)  Less mitochondria, actin, and myosin Muscular ____________  ____________ muscles due to increased ______/__________

Function cont…  Muscle strain/Pull ______ – few fibers injured, fascia still in tact, little loss of function ______ – many fibers and fascia injured and torn, loss of function, pain, discoloration, swelling of tissues

Function cont…  __________________ – sustained, forceful contraction that lacks relaxation  _________________ – Muscle contraction at time of death Muscles run out of _____, and Ca can NOT be removed Constant state of contraction for ____ hours or more ____ and ______ remain linked until muscle cells decompose

X. Life Span Changes  myoglobin, ATP, and creatine phosphate decline  by age 80, half of muscle mass has atrophied  adipose cells and connective tissues replace muscle tissue  exercise helps to maintain muscle mass and function

XI. Clinical Applications Myasthenia Gravis autoimmune disorder receptors for acetylcholine on muscle cells are attacked weak and easily fatigued muscles result difficulty swallowing and chewing ventilator needed if respiratory muscles are affected treatments include drugs that boost acetylcholine removing thymus gland immunosuppressant drugs antibodies