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MUSCULAR SYSTEM
NHS - HUMAN ANATOMY/PHYSIOLOGY
Dr. Smith
CHAPTER 6
MUSCLES
600+ organs
 ONLY CONTRACT - GET SHORTER
 Muscular System made up of Skeletal,
cardiac, Smooth
 Striated Muscle Tissue: has cross strips or
striations - skeletal and cardiac
 Non - Striated: NO bands: IN - Voluntary
 Cardiac - involuntary striations
Types of Muscle Tissue
Striated
 Skeletal - responsible for
moving bones voluntary
 Cardiac - bulk of heart,
has interclated disks keeps muscle in
contact - involuntary
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NON-STRIATED
 Smooth - involuntary,
blood vessel walls,
digestive system
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Each muscle served by one artery, one nerve, and
one or more veins
Enter/exit near central part and branch through
connective tissue sheaths
Every skeletal muscle fiber supplied by nerve
ending that controls its activity
Huge nutrient and oxygen need; generates large
amount of waste
STRUCTURE OF SKELETAL MUSCLE
 Origin - muscle attachment to bone - no
movement
 Insertion - muscle attachment to moveable
(joint)
 Tendons - anchor muscle to bone - great
strength/flexibility
 Bursae and synovial membranes
Muscle Microscopy
 Muscle fibers - muscle contractile cell
 Composed of thick and thin myofilaments
 Made of proteins
• Actin - thin filaments
• Myosin - thick filaments
SACROMERE (CONTRACTLIE UNIT)
 Area from Z line to Z line
Sliding Filament Model
 Muscles contract by thin myofilament
moving toward thick myofilament
 “Bridges” formed between the
myofilaments pull the sarcomeres closer
 Requires ATP and Ca
Major events in muscle contraction/relaxation
Energy Sources for Contraction
ATP molecules supply energy
 Creatine Phosphate make possible the formation
of ATP from ADP
 Creatine phosphokinase makes creatine
phosophate and stores additional energy

Oxygen role in muscle
contraction
 Hemoglobin - molecule that oxygen binds
to in RBC
 Myoglobin - molecule that oxygen “loosely”
binds to in muscle - makes them red
Functions of Skeletal Muscle
 Movement - muscle’s insertion bone moves
toward the origin
• prime mover - main muscle responsible for
movement
• synergist - helper muscles
• antagonist - produces opposite movement
FUNCTIONS OF MUSCULAR SYSTEM
POSTURE
Muscle tone
maintains posture
 Tonic contraction does not move body
parts - keeps posture opposite of gravity

HEAT PRODUCTION
Hypothermia decrease in body
temperature
 Hyperthermia increase in body
temperature

MUSCLE FATIGUE
 THE DECREASING STRENGTH OF MUSCLE
CONTRACTION
 OXYEGN DEBT INCREASES FATIGUE
 Lack of ACH, and lactic acid build up
support fatigue
 AEROBIC VS. ANAEROBIC RESPIRATION
NERVOUS SYSTEM AND MUSCLES
 NERVOUS SYSTEM - IMPORTANT ROLE IN
MUSCLE CONTRACTOIN - PARLYSIS - MULTIPLE
SCLEROISIS
 Muscle cells - stimulated by motor neurons
 Chemicals released at neuromuscular
junction
Stimuli
 Threshold stimulus - minimum level of
stimulation required for contraction.
 “All or nothing” - Once a muscle’s threshold
is reached all the muscle fibers contracts
all the way
 Recruitment - the amount of fibers involved
in contraction - the more fibers the more
strength
Types of Contraction
 Twitch - quick, jerky response to stimuli
 tetanic - sustained and steady contraction
(tetanus
 isotonic - muscle shortens - insertion
moves toward origin
 isometric - the same distance - tone of
muscle increases - - repeated isometric
makes muscles larger and stronger
Exercise on Skeletal Muscle
 During inactivity, muscles shrink in mass -
disuse atrophy
 Exercise causes increase in muscle size hypertrophy
 Strength training - heavy resistance increases myofilaments in muscle fiber
 endurance training (aerobic) - increases #
of blood vessels to/in muscles, increases
mitochondria
MUSCLES - FACIAL
Movements of Muscles
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Flexion - movement that makes angle between bones smaller
Extension - movement that makes angle between bone larger
Abduction - moving away from midline
Adduction - moving toward the midline
Rotation - movement around axis
Supination/Pronation - Movement to face up/ face down
Dorsiflexion/Plantary Flexion