Ch 9 Part 3) Muscles Flashcards

1
Q

Energy for Contraction

A
  • ATP supplies the energy needed fot muscle fiber too
    • Move and detach cross bridge
    • Pump calcium back into SR
    • and Pump Na+ and K+ in and out of cell
  • ATP in muscles is depleted in 4-6 seconds
    • Because of this it must be regenerated via one of three mechanisims.
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2
Q

Creatine Phosphate (CP)

A
  • Creatine Phosphate (CP) is a high energy molecule used to donate a phospate to ADP to make ATP
    • Creatine Phosphate + ADP → ATP
    • Done so by enzyme creatine kinase
  • Creatine creates enough ATP to power muscles for about 15 seconds
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3
Q

Anerobic Pathway (Glycolosis and Lactic Acid)

A
  • ATP can also be generated by breaking doww and using glucose as energy
  • Glycolysis) first step in glucose breakdown
    • Does not require oxygen (anerobic)
    • Glucose is broken down into 2 pyruvic acid molecules
    • 2 ATP’s made per glucose (2 total)
  • When in work, mucles can not get any oxygen to start conversion of pyruvic acid.
    • Pyruvic acid is made into Lactic Acid if no Oxygen is present
  • Latic Acid
    • Diffuses into bloodstream where it is made back into pyruvic acid/ glucose in the liver.
  • Anerobic Respiration only yealds about 5% of the ATP that Aerobic Respriation provides, but it is about 2 1/2 times faster
  • With CP and ATP stores, muscle activity can continue for about 20 seconds.
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4
Q

Aerobic Respriation

A
  • Produces 95% of ATP during rest or during moderate excercise
    • must have O2 present
    • Consists of a series of chemical reactions that occur in the midocondria
  • Glucose (C6H12O6) is broken into CO2 and H2O plus a large ammount of ATP (32 total)
    • C6H12O6→ CO2 + H2O + 32ATP
  • Fuel for Aerobic Respriation
    • First Glycogen stored in Mucscles
    • Second Bloodbourne Glucose
    • Lastly Free Fatty acids will be burned
      • Main fuel after 30 mins of excercise.
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5
Q

Which Pathway predominated during excercise?

A
  • If the muscle has O2, Aerobic Respriation is used to create ATP. When the excercise demands exceede the capicity of Aerobic excercise we will switch to Anerobic pathways to generate ATP
  • Aerobic Endurance) Length of time muscle contracts using aerobic pathways
  • Anerobic Threshold) Point at which metabolism changes to anerobic pathway.
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6
Q

Muscle Fatuige

A
  • Defined as the physilogical inability to contract despite continued stimulation
  • Possibe Causes of muscle fatuige include
    • Ionic Imbalances) K+, Na+, Ca2+ levels can be disturbed after continuious contraction
    • Increased Inorganic Phosphate levels may intefere with calcium release
    • Decreased Glycgoen levels
  • Muscles almost never run out of ATP.
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7
Q

Excess Postexcercise Oxygen Consumption (EPOC)

A
  • For a muscle to return to its pre-excercise state:
    • Oxygen reserves in myoglobin are replenished
    • Lactic acid is reconverted to pyruvic acid
    • Glycogen stores are replenished
    • ATP and Creatine Phosphate (CP) reserves are restored
  • These steps to restore the body need extra oxygen so this process is refered to as Excess Postexcercise Oxygen Consumption (EPOC)
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8
Q

Force of Contraction

A
  • Depends on number of cross bridges formed
  • Affected by four factors
    1. Number of muscle fibers stimulated (recruitment)
      • more fibers = more force
    2. Relative size of Fibers
      • Bulkier Fibers = more tenstion it can hold
    3. Frequcney of Stimulation
      • higher= more force
    4. Degree of Muscle Stretch
      • Sarcomeres are at optimal strength at 80-120% length
      • any more or less and not all myosin heads form crossbridges.
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9
Q

Velocity and Duration of Contractions

A
  • How fast a muscle contracts and how long are influenced by
    • Muscle Fiber Type
    • Load
    • and Recritument
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10
Q

Muscle Fiber Type

A
  • Classified according to two charcteristice
    • Speed of Contraction (Slow or Fast)
      • How fast ATPases split ATP
      • pattern of eletrical acticity
    • Metabolic pathways used for ATP synthesis
      • Oxadative) use aerobic pathways
      • Glycolytic) use anerobic pathways.
  • Sketeltal muscles can be classified into three types
    • Slow Oxidative Fibers) Low Intensity, Used for endurance activities
    • Fast Oxidative Fibers) Medium- intensity activities
      • Contract quickly but still depend on O2
    • Fast Glycolytic Fibers) Short-Intense movment
      • No O2 used
  • All fibers in one Motor unit will be the same
  • Genetics Dictate individual’s precentage of each type of fiber.
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11
Q

Load and Recritment

A
  • Load) Muscle Contract faster when there is no load
    • Greater the load, shorter the duration of contaction
    • More load = slower contraction
  • Recritument) More units contracting = faster and longer contraction
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12
Q

Aerobic Excercise (effects)

A
  • Leads to incresesed
    • Muscle capillaries
    • Number of mitochondria
    • Myoglobin synthesis
  • Results in greater endurance, strenght and resistance to fatuige.
  • Fast Glycotic Fibers may convert into Fast Oxidative Fibers
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13
Q

Resistance Excercise (effects)

A
  • Resistance (anerobic) excercice leads to muscle hytrophy
    • Increase in muscle strenght and size
    • Increased mitochondria, myofilaments, glycogen stores, and conenctive tissue
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14
Q

Atrophy

A
  • Muscles must be used to remain healthy
  • Atrophy is the loss of muscle mass due to unuse
    • Can be imobilized or have no stimulation
    • Begins almost immediately
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15
Q

Regeneration of Muscle

A
  • Skeletal Muscle) limited regenerative capicity
  • Cardiac Mucle (cardiomyocytes) devide at a modest rate
    • Injuries to heart are generally replaced with CT
  • Smooth Muscle) regenrated through life
  • Aging muscles = Loss of muscle mass (sarcopenia)
    • Begins at age 30
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16
Q

Develpoment

A
  • Muscles develop head to toe
    • A baby can lift its head before it can wals.