Muscle Metabolism

muscle contains ___ amounts of ATP and only enough to power contraction for a __ seconds

muscle contains low amounts of ATP and only enough to power contraction for a few seconds

Phosphagen system components

• Creatine phosphate (phosphocreatine) and ATP make up Phosphagen system

• creatine kinase

  • catalyzes this reaction

  • transfers a phosphate group from phosphocreatine to ADP, to form creatine and ATP

• Myokinase

  • is an enzyme in muscle that catalyzes the phosphorylation

    of one molecule of ADP by another, yielding ATP and AMP.

• phosphagen system energy amount

  • short burst of energy

phosphagen system energy amount (a lot or a little?)

• short sprint

• short burst of energy

Glycogen lactic acid system

• anaerobic (no oxygen)

• glucose is oxidized to produce ATP

• produces two molecules of ATP

• when not enough oxygen, pyruvic acid resulting from the breakdown of

  glucose is converted to lactic acid and diffuses in blood and goes to liver

• enough energy for 30-40 seconds of maximal muscle usage (100 meter dash)

Glycogen lactic acid system energy amount (a lot or a little?)

• enough energy for 30-40 seconds of maximal muscle usage (100 meter dash)

Aerobic System

• needs oxygen

• complete oxidation of glucose via cellular respiration

• produces 36 (skeletal) or 38 (cardiac) ATP per molecule of glucose

• enough energy for hours

Aerobic System system energy amount (a lot or a little?)

• a lot of energy for hours

Muscle and oxygen (2 carriers)

• oxygen can diffuse into muscle fibers from hemoglobin in the red blood cells

• oxygen is also released from myoglobin inside muscle fibers

Myogoblin

• similar to hemoglobin

• capable of reversible oxygenation and deoxygenation

Maximal Oxygen Uptake

• = maximum amount of oxygen that can be extracted from the

  external environment and transported to the working muscles

• more oxygen uptake means greater muscle strength and endurance and production of more molecules of ATP.

• unit:

  • ml of oxygen/minute/Kg of body weight = VO2 max.

• average 20 year old has about 40 VO2 max

• athelete has about 80 VO2 max

Elevation Training

• training at high elevations is good for increasing VO2 max (maximal oxygen uptake) because there is less oxygen

• elevation training masks

  • simulates training at higher elevations where there is less oxygen

endurance training

• isotonic contractions

  • increase the blood supply to skeletal muscle

• endurance training relies on aerobic production of ATP

• ex: jogging

Strength Training

• isometric contractions

• depends on anaerobic production of ATP (glycolysis)

• increase myofilaments whichi increases muscle size and builds muscle strength

  • (muscle hypertrophy)

• ex: weight lifting

Recovery Oxygen Consumption (Oxygen Debt)

Elevated oxygen use after exercise

(heavy breathing after stopping an exercise)

• this extra oxygen is needed for

  • gluconeogenesis - convert lactic acid to glycogen

  • Restore creatine phosphate and ATP

  • replaced oxygen removed from myoglobin

  • higher body temp = more ATP use = more oxygen need to make more ATP

  • ATP for heart and muscles

muscle fatigue

• inability of a muscle to maintain its strength of contraction

• muscle cannot produce enough ATP to meet its needs

Soreness after exercise is caused by __

Microscopic muscle damage

Skeletal Muscle Fibers properties

• color

  • red muscle fibers = high myoglobin = specialized for aerobic cellular respiration

  • white muscle fibers = low myoglobin = specialized for glycolysis

• fiber diameter

• contraction velocity

• Resistance to fatigue

All fibers of one motor unit are the ___

same (same type)

Skeletal Muscle Fiber type I

• type: slow

• ATP source: Aerobic

• Fatigue: resistant

• Contraction: slow

• Color: red

• Diameter: small

• Myoglobin: high

• Example: legs

Skeletal Muscle Fiber type IIB

• type: fast

• ATP source: Glycolysis

• Fatigue: Easily

• Contraction: Fast

• Color: white

• Diameter: large

• Myoglobin: low

• Example: arm

Skeletal Muscle Fiber type IIA

• type: intermediate

• ATP source: Aerobic/Glycolysis

• Fatigue: intermediate

• Contraction: intermediate

• Color: red

• Diameter: intermediate

• Myoglobin: intermediate

• Example: legs

Which skeletal muscle fiber can be found in skeletal muscle fibers?

• mixture of all three

  • I, IIA, IIB

weight lifting increases the number of which fibers?

fast glycolytic fibers

Marathon runners have more more of which fibers?

slow oxidative fibers

The number of muscle fibers is thought to ___ after birth

barely increase after birth

Increase in size is under the control of ____ and ___ in males.

human growth hormone, testosterone

anabolic steroids

• increases

  • muscle size, strength, and endurance

• side effects

  • liver cancer

  • kidney

    damage

  • increased risk of heart disease

  • mood swings.

isotonic contractions

• muscle changes its length while the tension or force remains relatively constant

• ex: bicep curls, jogging

isometric contractions

• length does not change and muscle generates force

• 
  

• (iso - equal, metric - length)

• ex: plank