Anatomy & Physiology I Unit Ten

Anatomy & Anatomy & Physiology IPhysiology I

Unit TenUnit Ten

Muscle CharacteristicsMuscle Characteristics

ContractilityContractilityExcitabilityExcitability

ExtensibilityExtensibilityElasticityElasticity

ConductivityConductivity


The ability to The ability to contractcontractContraction results in Contraction results in movementmovementContraction occurs due to Contraction occurs due to sliding filamentssliding filaments


Muscles contract due to nerve Muscles contract due to nerve activityactivityMuscles can be under Muscles can be under voluntary or involuntary voluntary or involuntary controlcontrol

Skeletal Muscle Skeletal Muscle CharacteristicsCharacteristics

Appear striatedAppear striatedUnder voluntary controlUnder voluntary controlQuick response time due to Quick response time due to nerve stimulation of nerve stimulation of independently contracting independently contracting muscle fibersmuscle fibersResults in body movement and Results in body movement and balancebalance

Smooth Muscle Smooth Muscle CharacteristicsCharacteristics

Appear non-striatedAppear non-striatedUnder involuntary controlUnder involuntary controlRelatively slow response time Relatively slow response time due to stimulation produced by due to stimulation produced by pacemaker potentialspacemaker potentialsResults in internal organ Results in internal organ movements and glandular movements and glandular secretionssecretions

Cardiac Muscle Cardiac Muscle CharacteristicsCharacteristics

Appear striatedAppear striatedUnder involuntary controlUnder involuntary controlQuick response time due to Quick response time due to pacemaker produced action pacemaker produced action potentialspotentials

Cardiac Muscle Cardiac Muscle CharacteristicsCharacteristics

Intercalated discs connecting Intercalated discs connecting fibers produce simultaneous fibers produce simultaneous contractioncontractionResults in heart beats and the Results in heart beats and the movement of bloodmovement of blood

Muscle Muscle AnatomAnatom

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Muscle AnatomyMuscle Anatomy

Filament Filament ArrangementArrangement

Actin Actin Filament Filament

CompositionComposition

Myosin ActionMyosin Action

The The Power Power StrokeStroke

Conduction Conduction in the in the

Muscle CellMuscle Cell

Motor UnitMotor Unit

Muscle Muscle ContractiContracti

on on SequenceSequence

Muscle Contraction Muscle Contraction SequenceSequence

Muscle Muscle ContractioContractio

n n SequenceSequence

Muscle Muscle ContractiContracti

on on SequenceSequence

Muscle Energy SourcesMuscle Energy Sources

ATP - as noted previously, ATP ATP - as noted previously, ATP is necessary for energizing is necessary for energizing myosin cross bridges and myosin cross bridges and accumulating Caaccumulating Ca2+2+ at the end at the end of contractionof contraction


ADP - as noted previously, ADP - as noted previously, ADP cycles with ATP in the ADP cycles with ATP in the power stroke and is necessary power stroke and is necessary for engaging and disengaging for engaging and disengaging myosin cross bridgesmyosin cross bridges

Atrophy vs. Atrophy vs. HypertrophyHypertrophy

Myoglobin is a pigment found Myoglobin is a pigment found in skeletal muscle cells that in skeletal muscle cells that functions to take up and store functions to take up and store oxygen for use in the celloxygen for use in the cellMyoglobin provides a supply Myoglobin provides a supply of ready oxygen needed for of ready oxygen needed for muscle contractionmuscle contraction


Atrophy is the decrease in the Atrophy is the decrease in the mass and size of muscle tissue mass and size of muscle tissue due to inactivitydue to inactivityHypertrophy is the increase in Hypertrophy is the increase in the mass and size of muscle the mass and size of muscle tissue due to increased tissue due to increased activityactivity


Steroid hormones will Steroid hormones will increase protein synthesis in increase protein synthesis in muscle tissue, producing muscle tissue, producing hypertrophyhypertrophyTestosterone, found in males, Testosterone, found in males, is one such hormone that is one such hormone that naturally increasing muscle naturally increasing muscle size in malessize in males

Twitches and SummationTwitches and Summation

Summation and its ResultsSummation and its Results

TonusTonus

Tonus is an example of a Tonus is an example of a graded response that is used graded response that is used to maintain position or to maintain position or postureposture

DefinitionsDefinitionsIsotonic contractions - Isotonic contractions - contractions that result in contractions that result in the shortening of a muscle the shortening of a muscle and movementand movementIsometric contractions - Isometric contractions - contractions that do not contractions that do not shorten a muscle and result in shorten a muscle and result in no movementno movement

Contraction Functions Contraction Functions

Isotonic contractions are Isotonic contractions are used to produce movement in used to produce movement in the bodythe body

Isometric contractions are Isometric contractions are used to maintain tone, used to maintain tone, position and postureposition and posture

Refractory PeriodRefractory Period

Muscle DisordersMuscle Disorders

Muscular dystrophy:Muscular dystrophy: ~ sex linked recessive ~ sex linked recessive diseasedisease ~ affected muscles fill with ~ affected muscles fill with fat & fat & connective tissue causing connective tissue causing muscle muscle tissue to atrophytissue to atrophy ~ caused by the lack of ~ caused by the lack of dystrophindystrophin


Myasthenia gravis:Myasthenia gravis: ~ may be an autoimmune ~ may be an autoimmune diseasedisease ~ affected muscles develop ~ affected muscles develop weakness due to a reduced weakness due to a reduced number of acetylcholine number of acetylcholine receptorsreceptors ~ receptor numbers are ~ receptor numbers are gradually gradually reduced as disease reduced as disease progresses progresses


Strain:Strain: ~ also called a pulled muscle~ also called a pulled muscle ~ excessive stretching or ~ excessive stretching or tearing tearing of a muscle due to overuse of a muscle due to overuse or or abuseabuse


Shin splints:Shin splints: ~ irritation of the tibialis ~ irritation of the tibialis anterioranterior ~ caused by excessive use of ~ caused by excessive use of the the muscle without prior muscle without prior conditioningconditioning ~ its inflammation causes ~ its inflammation causes swelling swelling and intense painand intense pain

Anatomy & Physiology I Unit Ten

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