MUSCULAR SYSTEMMUSCULAR SYSTEM

NHS - HUMAN NHS - HUMAN ANATOMY/PHYSIOLOGYANATOMY/PHYSIOLOGY

Dr. SmithDr. Smith

CHAPTER 6CHAPTER 6

MUSCLESMUSCLES

600+ organs600+ organs ONLY CONTRACT - GET SHORTERONLY CONTRACT - GET SHORTER Muscular System made up of Skeletal, Muscular System made up of Skeletal,

cardiac, Smoothcardiac, Smooth Striated Muscle Tissue: has cross strips Striated Muscle Tissue: has cross strips

or striations - skeletal and cardiacor striations - skeletal and cardiac Non - Striated: NO bands: IN - VoluntaryNon - Striated: NO bands: IN - Voluntary Cardiac - involuntary striationsCardiac - involuntary striations

Types of Muscle TissueTypes of Muscle Tissue

StriatedStriated Skeletal - - Skeletal - -

responsible for responsible for moving bones - moving bones - voluntaryvoluntary

Cardiac - bulk of Cardiac - bulk of heart, has heart, has interclated disks - interclated disks - keeps muscle in keeps muscle in contact - involuntarycontact - involuntary

NON-STRIATEDNON-STRIATED Smooth - Smooth -

involuntary, blood involuntary, blood vessel walls, vessel walls, digestive systemdigestive system

Each muscle served by one artery, one nerve, and one or more veins

Enter/exit near central part and branch through connective tissue sheathsEvery skeletal muscle fiber supplied by nerve ending that controls its activityHuge nutrient and oxygen need; generates large amount of waste

STRUCTURE OF SKELETAL STRUCTURE OF SKELETAL MUSCLEMUSCLE

Origin - muscle attachment to bone - Origin - muscle attachment to bone - no movementno movement

Insertion - muscle attachment to Insertion - muscle attachment to moveable (joint)moveable (joint)

Tendons - anchor muscle to bone - Tendons - anchor muscle to bone - great strength/flexibilitygreat strength/flexibility

Bursae and synovial membranes Bursae and synovial membranes

Muscle MicroscopyMuscle Microscopy

Muscle fibers - muscle contractile Muscle fibers - muscle contractile cellcell

Composed of thick and thin Composed of thick and thin myofilamentsmyofilaments

Made of proteins Made of proteins • Actin - thin filamentsActin - thin filaments• Myosin - thick filamentsMyosin - thick filaments

SACROMERE SACROMERE (CONTRACTLIE UNIT)(CONTRACTLIE UNIT)

Area from Z line to Z lineArea from Z line to Z line

Sliding Filament ModelSliding Filament Model

Muscles contract by thin Muscles contract by thin myofilament moving toward thick myofilament moving toward thick myofilamentmyofilament

““Bridges” formed between the Bridges” formed between the myofilaments pull the sarcomeres myofilaments pull the sarcomeres closercloser

Requires ATP and CaRequires ATP and Ca

Major events in muscle contraction/relaxationMajor events in muscle contraction/relaxation

Energy Sources for Energy Sources for ContractionContraction ATP molecules supply energy ATP molecules supply energy Creatine Phosphate make possible the Creatine Phosphate make possible the

formation of ATP from ADPformation of ATP from ADP Creatine phosphokinase makes creatine Creatine phosphokinase makes creatine

phosophate and stores additional phosophate and stores additional energyenergy

Oxygen role in muscle Oxygen role in muscle contractioncontraction

Hemoglobin - molecule that Hemoglobin - molecule that oxygen binds to in RBCoxygen binds to in RBC

Myoglobin - molecule that oxygen Myoglobin - molecule that oxygen “loosely” binds to in muscle - “loosely” binds to in muscle - makes them redmakes them red

Functions of Skeletal Functions of Skeletal MuscleMuscle

Movement - muscle’s insertion Movement - muscle’s insertion bone moves toward the originbone moves toward the origin• prime mover - main muscle prime mover - main muscle

responsible for movementresponsible for movement• synergist - helper musclessynergist - helper muscles• antagonist - produces opposite antagonist - produces opposite

movementmovement

FUNCTIONS OF MUSCULAR FUNCTIONS OF MUSCULAR SYSTEMSYSTEM

Muscle tone Muscle tone maintains posturemaintains posture

Tonic contraction Tonic contraction - does not move - does not move body parts - body parts - keeps posture - keeps posture - opposite of opposite of gravitygravity

Hypothermia - Hypothermia - decrease in body decrease in body temperaturetemperature

Hyperthermia - Hyperthermia - increase in body increase in body temperaturetemperature

POSTURE HEAT PRODUCTION

MUSCLE FATIGUEMUSCLE FATIGUE

THE DECREASING STRENGTH OF THE DECREASING STRENGTH OF MUSCLE CONTRACTIONMUSCLE CONTRACTION

OXYEGN DEBT INCREASES FATIGUEOXYEGN DEBT INCREASES FATIGUE Lack of ACH, and lactic acid build Lack of ACH, and lactic acid build

up support fatigue up support fatigue AEROBIC VS. ANAEROBIC AEROBIC VS. ANAEROBIC

RESPIRATIONRESPIRATION

NERVOUS SYSTEM AND NERVOUS SYSTEM AND MUSCLESMUSCLES

NERVOUS SYSTEM - IMPORTANT NERVOUS SYSTEM - IMPORTANT ROLE IN MUSCLE CONTRACTOIN - ROLE IN MUSCLE CONTRACTOIN - PARLYSIS - MULTIPLE SCLEROISISPARLYSIS - MULTIPLE SCLEROISIS

Muscle cells - stimulated by motor Muscle cells - stimulated by motor neuronsneurons

Chemicals released at Chemicals released at neuromuscular junctionneuromuscular junction

StimuliStimuli

Threshold stimulus - minimum level of Threshold stimulus - minimum level of stimulation required for contraction.stimulation required for contraction.

““All or nothing” - Once a muscle’s All or nothing” - Once a muscle’s threshold is reached all the muscle threshold is reached all the muscle fibers contracts all the wayfibers contracts all the way

Recruitment - the amount of fibers Recruitment - the amount of fibers involved in contraction - the more involved in contraction - the more fibers the more strengthfibers the more strength

Types of ContractionTypes of Contraction

Twitch - quick, jerky response to stimuliTwitch - quick, jerky response to stimuli tetanic - sustained and steady tetanic - sustained and steady

contraction (tetanuscontraction (tetanus isotonic - muscle shortens - insertion isotonic - muscle shortens - insertion

moves toward originmoves toward origin isometric - the same distance - tone of isometric - the same distance - tone of

muscle increases - - repeated isometric muscle increases - - repeated isometric makes muscles larger and stronger makes muscles larger and stronger

Exercise on Skeletal Exercise on Skeletal MuscleMuscle

During inactivity, muscles shrink in During inactivity, muscles shrink in mass - disuse atrophymass - disuse atrophy

Exercise causes increase in muscle size Exercise causes increase in muscle size - hypertrophy- hypertrophy

Strength training - heavy resistance - Strength training - heavy resistance - increases myofilaments in muscle fiberincreases myofilaments in muscle fiber

endurance training (aerobic) - increases endurance training (aerobic) - increases # of blood vessels to/in muscles, # of blood vessels to/in muscles, increases mitochondriaincreases mitochondria

MUSCLES - FACIALMUSCLES - FACIAL

Movements of MusclesMovements of Muscles

Flexion - movement that makes angle between Flexion - movement that makes angle between bones smallerbones smaller

Extension - movement that makes angle Extension - movement that makes angle between bone largerbetween bone larger

Abduction - moving away from midlineAbduction - moving away from midline Adduction - moving toward the midlineAdduction - moving toward the midline Rotation - movement around axisRotation - movement around axis Supination/Pronation - Movement to face up/ face Supination/Pronation - Movement to face up/ face

downdown Dorsiflexion/Plantary FlexionDorsiflexion/Plantary Flexion