A&p 10 Muscle Tissue-Continued

A&p 10 Muscle Tissue-Continued - Muscle...

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Unformatted text preview: Muscle Tissue-Continued Muscle Chapter 10 1 Basic Physical Principles Basic Factors affecting strength of muscle Factors contraction are; Tension Load Number of Fibers 2 Muscle Tension Muscle When muscle cells contract tension is When created. created. Muscle force is used to overcome load or Muscle resistance resistance 3 Muscle Tension Muscle Active force of pull on an object Depends on Internal tension Myofibrils External tension Extracellular fibers Connective Tissue Wrappings Tendons 4 Load (Resistance=R) Load Passive force that opposes movement Depends on objects Weight (gravity) Shape Surface shape Friction Muscles contract stronger when more Muscles tension is present tension 5 Number of Fibers Number More fibers contracting greater force of contraction contraction Different muscle movements require different numbers of muscle fibers different Type of Movement Performed Precision of Movement Performed 6 Different Types of Movements Weak movement Weak Blink or wink eyes Small numbers of fibers contracting Strong movement Close eye tightly Large numbers of fibers contracting 7 Different Precision of Movements Depends on Number and size of muscle cells stimulated by one motor neuron =(Motor Unit) 8 Precise Movements Precise More precise a More movement is the less fibers per motor unit fibers Eye muscles 1 fiber per motor unit Finger muscles 10 fibers per motor unit Back muscles 100 fibers per motor 100 unit unit 9 Proprioceptors Proprioceptors Tell us if we are in the appropriate position Stretching of the muscle or tendon excites Stretching these receptors these Muscle Spindle Provides info. about muscle length Provides length Golgi Tendon Organ Provides info. about muscle tension 10 Muscular Responses Muscular Investigating & Learning about muscle Investigating contraction in the laboratory contraction 11 Muscular Responses Muscular Myogram Graphic recording of a muscle ‘s contractile Graphic activity activity Tracing Visual Recording of activity Paper or on a screen 12 Characteristics of a Single Muscle Fiber Muscle All or None Response A single muscle fiber will either contract or single not contract not There is no “partial” contraction 13 Muscle Twitch Muscle Twitch The mechanical response of a motor unit to a The single action potential or nerve impulse of its motor neuron. motor Measures muscle tension 14 Muscle Twitch Muscle Muscle fibers contract quickly then relax Lasts about 30-40 msec Divided into 1. Latent period 2. Period of contraction 2. contraction 3. Period of relaxation 4. Refractory period 15 Muscle Twitch Muscle 16 Muscle Twitch Muscle Latent Period Delay between the time the nerve stimulus is Delay applied & the muscle fiber responds applied Time required for the release of calcium. Tension Changes No tension recorded in muscle Electrical Changes Depolarization and repolarization are occurring 17 Muscle Twitch Muscle Contraction Phase Time during which muscle actually shortens Tension Changes Muscle pulls on attachments Tension rises to a peak. Electrical Changes Cross bridging occurs 18 Muscle Twitch Muscle Relaxation Muscle relaxes & returns to former length Ca levels fall Crossbridges released Tension falls 19 Muscle Twitch Muscle Refractory period Brief time after a contraction starts when Brief muscle cannot respond to a nerve stimulus muscle Occurs early in the contraction period 20 Twitch Myogram of Different Muscles Muscles Some twitch contractions are rapid & brief Eye muscle movement Some are slow & last a long time Calf muscles 21 Normal Muscular Contraction of Entire Muscle Entire Smooth not jerky Graded Different according to demands placed on Different them them 22 Normal Muscular Contraction of Entire Muscle Entire 2 ways to Grade Increase frequency of stimulus Nerves fire faster Increase strength of stimulus More nerves fire 23 Increase Frequency of Stimulus Increase Repeated same strength stimulation after Repeated relaxation phase has been completed relaxation Called Treppe Means “Stairs” Muscle tension rises like stairs Occurs during normal muscle warm up 24 Increasing Frequency of Stimulation Stimulation Nerves fire faster Repeated Stimulation before Relaxation Repeated Phase ends Phase Twitches will add together Called Wave Summation or Summation of Called Twitches Twitches 25 Increasing Frequency of Stimulation- More StimulationRepeated stimulation as soon as Repeated relaxation starts relaxation Results in sustained contraction with some Results relaxation in between. relaxation But not maximal But Called Incomplete Tetanus Or Unfused Tetanus Tetan/o Tetan/o Means rigid or tense 26 Increasing Frequency of Stimulation- Even More StimulationRepeated nerve stimulation even before Repeated relaxation starts relaxation Peak Tension is produced Peak Called Complete Tetanus Or Fused Tetanus All normal muscle contraction is Complete All Tetanus. Tetanus 27 Putting it all Together Putting 28 We thought Tetanus was a disease??? We Tetanus the movement Versus Tetanus the disease 29 Tetanus the Movement Tetanus Peak tension of muscle contraction Maximum or convulsive contraction Sustained contractions are essential for useful Sustained movements. 30 30 Tetanus –the Disease (Lock Jaw) (Lock Caused by bacteria in soil / environment Named Clostridium tetani Named Usually due to a contaminated puncture Usually wound Bacteria produces neurotoxin Bacteria Causes motor neurons to uncontrollably Causes transmit action potentials transmit 31 Tetanus –the Disease (Lock Jaw) Jaw) Results in severe muscle spasms Abnormal, sustained, powerful contractions. Muscles are unable to relax voluntarily First sign/symptom is lockjaw Difficulty to opening mouth Difficulty 32 32 Increasing the Strength of a Stimulus Stimulus Threshold Stimulus Minimal strength of a nerve stimulus in order Minimal for a muscle to contract for Not all motor units are recruited or stimulated Muscle tone Minimal graded response State of partial contraction in a muscle State (posture) (posture) Stabilizes bones and joints 33 Increasing the Strength of a Stimulus Stimulus Maximum Stimulus Strongest stimulus to get maximal muscle Strongest contraction. contraction. All motor units are recruited or stimulated. Called Recruitment or Motor Unit Called Summation Summation Smooth but steady increase in muscle tension Gives the strongest muscle contraction 34 Types of Muscle Contractions Types Resistance Stays the Same Isotonic Equal tension Isometric Equal length Resistance Varies Isokinetic Equal movement 35 Isotonic Contraction Isotonic Isotonic contractions Muscle contracts & changes length Resistance stays same Concentric Shortening contraction Eccentric Eccentric Lengthening contraction 36 Isometric Contraction Isometric Isometric Contraction Muscle contracts but does not change Muscle length length Resistance stays the same Tension in the muscles increases 37 Isokinetic Contraction Isokinetic Isokinetic contractions Isokinetic Length of muscle shortens at a Length constant speed. constant Resistance varies Tension varies 38 Summary-Force of Muscle Contraction Contraction Affected by; 1. Number fibers stimulated Increased number of motor units recruited greater the muscle force . greater 2. Relative size of the fibers Hypertrophy -enlargement of musclesstronger stronger Atrophy -shrinking of musclesweaker 3. Frequency of stimulation Increased rapidity muscle stimulation greater the muscle force . greater 4. Degree of muscle stretch 4. Muscle is strongest if stretched prior to contracting 39 Hypertrophy Hypertrophy 40 Summary-Force of Muscle Ctx. Summary-Force Contracts most forcefully when stimulated Contracts over a narrow range of resting lengths. over 41 Muscle Metabolism Muscle Contracting muscle fibers Use huge amounts of energy (ATP) Requires a continuous supply of; Oxygen Nutrients Especially Glucose 42 Energy for Muscle Contraction Energy Initially, muscles use stored ATP Initially, Lasts only 4-6 seconds Lasts After this other pathways must be utilized to produce ATP to 43 Generation of ATP in Skeletal Muscle Muscle 3 ways to generate ATP in muscle 1) Creatine phosphate 2) Glycolysis Break down glycogen 3) Cellular Respiration Kreb’s Cycle Cytochrome Electron Transport 44 Energy for Muscle Contraction Energy 1. Creatine Phosphate (CP) 1. Phosphate CP is a high-energy molecule 1 CP transfers energy to ADP to regenerate 1 CP ATP ATP CP supplies are exhausted in about 15-20 seconds 45 Anaerobic Phase Anaerobic Glycolysis Anaerobic Reaction that breaks down glucose without O2 Occurs in cytoplasm Generates enough ATP for 30-60 sec. 2 ATP per molecule of glucose If O2 is available then proceeds to Kreb’s If Cycle. Cycle. *If no O2 is present lactic acid builds up & *If leads to muscle fatigue. leads 2 ATP per 1 molecule of lactic acid 46 Muscle Fatigue Muscle Muscle can no longer continue to perform Muscle at the required level of activity. at Lack of O2 causes ATP deficit Lactic acid build up causes decrease in pH. Becomes more acid Becomes unable to contract 47 Aerobic Phase Aerobic Series of metabolic pathways that occur in Series the mitochondria the Kreb’s Cycle Cytochrome Electron Transport Provides large amounts of ATP 36 ATP per 1 molecule of glucose Can use other nutrients also Lasts hours 48 Aerobic Phase Aerobic Glucose is broken down to carbon dioxide Glucose and water, releasing energy and This is a slower reaction that requires This continuous oxygen continuous Myoglobin stores O2 in muscle 49 Summary -Cellular Respiration Respiration Anaerobic Phase Glycolysis Occurs in cytoplasm Produces little ATP Produces Aerobic Phase Complete metabolism of glucose Kreb’s Cycle or Citric acid cycle Kreb’s cycle Cytochrome Electron transport chain Occurs in the mitochondria 50 ENERGY SYSTEMS USED DURING SPORTS ACTIVITIES DURING Muscles use endurance & power during Muscles different types of training activities. different Endurance Amount of time an individual can perform an Amount time activity. activity. Power Maximum amount of tension produced during Maximum tension activity. activity. 51 Training Training Endurance Activities Endurance Aerobic; so rely on ongoing aerobic Aerobic; metabolism metabolism Moderate levels of activity Moderate Ex; long distance running 52 Training Training Power Activities Power Surge of power needed for only a few Surge seconds seconds Rely entirely on ATP & CP stores Rely Ex; weight-lifting, diving, and sprinting Ex; 53 Energy Released During Muscle Contraction Contraction Heat Production 60% of muscle activity Is released as heat Work done 40% of muscle activity was converted to useful 40% work work 54 What About After Activity?? What Recovery Period Conditions inside muscle need to return to Conditions normal normal Replenish O2, Glycogen, ATP, CP, cool down 55 Most common reason for muscle fatigue is oxygen debt oxygen Oxygen must be “repaid” to tissue. 56 Oxygen Debt Oxygen Oxygen is required to get rid of Oxygen accumulated lactic acid accumulated 57 Velocity & Duration of Contraction Contraction 2 Major Functional Characteristics of Major Muscle Fibers Muscle 1. Velocity How fast they can contract 2. Duration How long they can contract before fatigue Depends on pathways to generate ATP 58 Velocity & Duration of Contraction Contraction Determined by Type of Muscle Fiber Load or Resistance # of Motor Units Recruited Type are Fast Twitch, Slow Twitch & Type Intermediate Twitch Intermediate 59 Fast Twitch Fibers Fast Type contractions Rapid, powerful contractions Brief duration White fibers Anaerobic metabolism Less myoglobin Poorer blood supply Susceptible to fatigue Example Chicken wings 60 Slow Twitch Fibers Slow Type contractions Slow, prolonged Red fibers Aerobic metabolism Most myoglobin Good blood supply Resistant to fatigue Example Chicken Thighs Chicken 61 61 Intermediate Fibers Intermediate Possess qualities of both slow and fast Possess twitch fibers twitch Aerobic Metabolism Intermediate amount of myoglobin Pink to red in color Pink Resistant to fatigue 62 Slow Fibers-Fast Fibers Slow Everyone’s muscles contain mixtures of Everyone’s the 3 fiber types; but genetically can have relatively more of one variety relatively 63 Effects of Exercise on Muscle Effects Results of increased muscle use Increase in muscle size Increase in muscle strength Increase in muscle efficiency Muscle becomes more fatigue resistant 64 Physical Conditioning Physical Anaerobic Endurance No O2 Time of contraction using glycolysis, ATP. CP Muscle changes Hypertrophy High intensity resistance exercise Example Weight lifting 65 Physical Conditioning Physical Aerobic Endurance Use of O2 Time of contraction using mitochondrial Time acitivities acitivities Muscle changes Increase in capillaries, mitochondria, & myoglobin Example Running or jogging 66 Exercise Homeostasis Exercise Moderate or strenuous exercise is a stress Moderate situation situation Brain Generates electrical impulses Generates contraction contraction Coordinates those contractions Regulates Heart rate Breathing rate Vasodilation of blood vessels for muscle 67 Exercise Homeostasis Exercise Cardiovascular Maintains heart rate, blood pressure, blood Maintains flow Respiratory Maintains exchange of O2 & CO2 Maintains Integument Skin eliminates excess body heat Skin sweating & evaporation 68 68 Training Training Balance Balance Between forcing muscle to work Allowing muscle to recover & repair 69 OVERUSE INJURIES OVERUSE Overdoing it Prevention Prevention Change or restrict activity Use ice after workout to prevent or reduce Use inflammation inflammation Taking non-steroidal, anti-inflammatory meds Taking to reduce pain to 70 Treatment for Overuse Injuries Treatment RICE REST ICE COMPRESSION ELEVATION 71 Hormones & Muscles Hormones Hormones Hormones Can alter muscular activity Testosterone Growth Hormone Both stimulate synthesis of contractile Both proteins & muscle enlargement proteins 72 Drug Abuse by Athletes Drug Anabolic steriods Synthetic Androgens Side Effects Liver Problems Mental Disorders Infertility Cholesterol Disorders 73 Muscles & Aging Muscles With age muscle cells Die & are replaced by adipose cells and Die connective tissues connective By age 80, half of muscle mass has atrophied Become slower & strength decreases Myoglobin, ATP, and creatine phosphate Myoglobin, decline decline 74 Muscles & Aging Muscles Loss of proprioception Loss Muscle Sensory proprioceptors are lost Muscle Causes falls 75 75 Aging and Exercise Aging Regular exercise helps to maintain Regular muscle mass and function muscle Delays atrophy Maintains muscle function for activities of Maintains daily living daily Includes Lifting of small weights Lifting Moderate aerobic activites 76 ...
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This note was uploaded on 07/22/2011 for the course PTA 1001 taught by Professor Rice during the Spring '11 term at South University Online.

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