Muscular SystemMuscular System

Sports Training and Sports Training and PhysiologyPhysiology

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Muscular System - ObjectivesMuscular System - ObjectivesList the major functions of musclesList the major functions of musclesDescribe 4 major properties of musclesDescribe 4 major properties of musclesCompare and contrast the 3 different Compare and contrast the 3 different

types of musclestypes of musclesExplain the sliding filament theoryExplain the sliding filament theoryDefine a muscle twitch and it’s 3 phasesDefine a muscle twitch and it’s 3 phasesDefine the different types of muscle Define the different types of muscle

contractionscontractions

Muscular System – Objectives Muscular System – Objectives 22

Name and compare the types of Name and compare the types of skeletal muscle fibersskeletal muscle fibers

Discuss the causes of fatigue during Discuss the causes of fatigue during exerciseexercise

Explain how fibers obtain energyExplain how fibers obtain energyDiscuss causes of hypertrophy and Discuss causes of hypertrophy and

atrophyatrophyDiscuss age related changes in Discuss age related changes in

skeletal muscleskeletal muscle

Functions of the Muscular Functions of the Muscular SystemSystem

Body MovementBody MovementMaintenance of postureMaintenance of postureRespirationRespirationProduction of body heatProduction of body heatCommunicationCommunicationConstriction of organs and vesselsConstriction of organs and vesselsHeartbeat Heartbeat

Functional Properties of Functional Properties of MusclesMuscles

ContractilityContractility The ability to The ability to

shorten forcefullyshorten forcefully ExcitabilityExcitability

Ability to respond to Ability to respond to a stimulusa stimulus

ExtensibilityExtensibility Ability of a muscle Ability of a muscle

to be stretched to be stretched beyond it’s normal beyond it’s normal resting lengthresting length

ElasticityElasticity Ability of a muscle Ability of a muscle

to recoil to it’s to recoil to it’s original shape after original shape after it has been it has been stretchedstretched

Muscle Tissue3 kinds or types

Skeletal Muscle•Attached to bones

Smooth Muscle•Walls of hollow

organs•Blood vessels•Eyes, glands,

and skin

Cardiac Muscle•Found only in The heart

Connective tissue coverings of a Connective tissue coverings of a MuscleMuscle

Anatomy of the Skeletal Anatomy of the Skeletal MuscleMuscle Filaments found in Filaments found in

the myofibrilsthe myofibrils ActinActin MyosinMyosin

Together they make Together they make sarcomeres that sarcomeres that make up…make up…

Myofibrils: Myofibrils: threadlike structure threadlike structure that extends from that extends from one end of the one end of the muscle to the othermuscle to the other

How do muscles How do muscles contract?contract?

Sliding Filament ModelSliding Filament Model

Muscle Twitch:Muscle Twitch: contraction and contraction and relaxation to a stimuli that causes relaxation to a stimuli that causes

action potential in one or more muscle action potential in one or more muscle fibersfibers

Lag/Latent phase: time it takes to Lag/Latent phase: time it takes to stimulate the motor neuron to stimulate the motor neuron to cause the muscle to contractcause the muscle to contract

Contraction phase: time during Contraction phase: time during which a contraction occurswhich a contraction occurs

Relaxation phase: time in which Relaxation phase: time in which relaxation occursrelaxation occurs

Types of Muscle ContractionsTypes of Muscle Contractions Isometric:Isometric:

Length doesn’t Length doesn’t change, but tension change, but tension increases during the increases during the contraction phasecontraction phase

Muscle Tone:Muscle Tone: Constant tension Constant tension

produced over long produced over long periods of timeperiods of time

Isotonic: Isotonic: Amount of tension is Amount of tension is

constant but length constant but length changeschanges

Concentric: Concentric: shortening a muscleshortening a muscle

Eccentric: Eccentric: lengthening a lengthening a

musclemuscle

How do the muscles get energy How do the muscles get energy to contract? to contract?

ATP is the immediate source of ATP is the immediate source of energy used by the musclesenergy used by the muscles

ATP must be used continuously in ATP must be used continuously in order to keep a muscle contractedorder to keep a muscle contracted

3 ways body makes ATP production 3 ways body makes ATP production for the musclesfor the musclesCreatine phosphateCreatine phosphateAnaerobic glycolysisAnaerobic glycolysisAerobic respirationAerobic respiration

ATP Production happens in the ATP Production happens in the mitochondriamitochondria

Creatine Creatine Phosphate: Phosphate: Energy Source is Energy Source is

creatine phosphate creatine phosphate Creates 1 ATPCreates 1 ATP Oxygen is NOT Oxygen is NOT

requiredrequired Duration of energy Duration of energy

is 10 secondsis 10 seconds

Anaerobic Anaerobic Glycolysis:Glycolysis: Energy Source is Energy Source is

glucoseglucose Creates 2 ATPCreates 2 ATP Oxygen is NOT Oxygen is NOT

requiredrequired Duration of energy Duration of energy

is up to 3 minutesis up to 3 minutes

ATP Production happens in the ATP Production happens in the mitochondriamitochondria

Aerobic RespirationAerobic Respiration Energy Source is Energy Source is

glucose, lactic acid, glucose, lactic acid, fatty acids, amino fatty acids, amino acidsacids

Oxygen is required Oxygen is required Creates up to 36 Creates up to 36

ATP ATP Duration of energy Duration of energy

is hours!!!is hours!!!

Exercise and FatigueExercise and FatigueFatigue: decreased capacity to do Fatigue: decreased capacity to do

work and the reduced efficiency of work and the reduced efficiency of performance to do workperformance to do workPsychologic fatigue: most common type. Psychologic fatigue: most common type.

Individual perceives that they can not Individual perceives that they can not use the muscle anymoreuse the muscle anymore

Muscular fatigue: the reduced or absent Muscular fatigue: the reduced or absent ability of muscle fibers to respond to ability of muscle fibers to respond to stimulistimuli

Hypertrophy and AtrophyHypertrophy and Atrophy HypertrophyHypertrophy

Muscle size Muscle size increasesincreases

Slow and fast twitch Slow and fast twitch muscle fibers muscle fibers increase depending increase depending upon what upon what exercises you doexercises you do

AtrophyAtrophy Decrease in muscle Decrease in muscle

sizesize Disuse AtrophyDisuse Atrophy

Denervation Denervation AtrophyAtrophy

Age related changes in skeletal Age related changes in skeletal musclemuscle

Loss of muscle Loss of muscle fibers as early as fibers as early as the age of 25the age of 25

By 80 50% of By 80 50% of muscle mass is muscle mass is gonegone

Fast-twitch muscle Fast-twitch muscle fibers deteriorate fibers deteriorate faster than slow-faster than slow-twitchtwitch

Gross Anatomy Gross Anatomy Generalized Groupings of the Generalized Groupings of the

Muscles of the BodyMuscles of the Body

*We will go over in depth starting next *We will go over in depth starting next week with anatomy Mondays andweek with anatomy Mondays and

Injury/Rehab FridaysInjury/Rehab Fridays

The Muscular SystemThe Muscular System