Lecture 6: Supplying Energy for Skeletal Muscle Contraction

parts of ATP

• Phosphatases (-P)

• Kinases (+P)

ATP in skeletal tissues hydrolyzed by _______ into ADP and Pi

myosin ATPase

direct phosphorylation of ADP

• immediate ATP supply

• produces 10-15 seconds of activity fueled by ATP

creatine phosphate (CP) provides

the phosphate used to convert ADP to ATP

glucose can be used to generate ATP through

cellular respiration

anaerobic cellular respiration (glycolysis)

• short term ATP supply

• produces 30-40 seconds of activity fueled by ATP

for glycolysis, glucose comes from

the blood or glycogen stores

glycolysis occurs in

cytosol

in glycolysis, glucose is converted into two

pyruvic acid (pyruvate) molecules

glucose being converted into two pyruvate molecules results in

production of 2 ATP molecules

what is produced because of compression of blood vessels during intense activity?

lactic acid

long term ATP supply

aerobic cellular respiration

in aerobic cellular respiration, energy is used to generate ATP by

oxidative phosphorylation

aerobic cellular respiration produces

32 net ATP per glucose molecule

oxygen is bound to a protein called

myoglobin

types of skeletal muscle fibers

• slow oxidative (slow-twitch, Type I)

• fast oxidative (fast-twitch, Type IIa)

• fast glycolytic (fast-twitch, Type IIb)

slow oxidative fibers

• high myoglobin content

• slow rate of fatigue

• many mitochondria

primary pathway for ATP synthesis in slow oxidative fibers

aerobic

activities best suited for slow oxidative fibers

endurance type activities

fast oxidative fibers

• high myoglobin content

• intermediate rate of fatigue

• many mitochondria

primary pathway for ATP synthesis in fast oxidative fibers

aerobic (some anaerobic glycolysis)

activities best suited for fast oxidative fibers

sprinting, walking

fast glycolytic fibers

• low myoglobin content

• fast rate of fatigue

• few mitochondria

primary pathway for ATP synthesis in fast glycolytic fibers

anaerobic glycolysis

activities best suited for fast glycolytic fibers

short-term intense or powerful movements

postural muscles have a high percentage of

slow oxidative fibers

structural changes in muscle gained from a sustained strength training exercise program (resistance exercise)

hypertrophy and hyperplasia

hypertrophy

increase in muscle fiber size

hyperplasia

increase in number of muscle fibers following longitudinal splitting

large increase in force production (in exercise) =

increased motor unit activation

effects of endurance exercise

• increase number of capillaries

• increase number of mitochondria

• fibers synthesize more myoglobin

exercise slows

muscle aging

fibrosis

muscle mass is replaced by dense regular CT

disuse atrophy

individual fiber atrophy (loss of myofibrils) without loss of muscle fibers

heart responds to exercise similarly to

skeletal muscle

blood pressure decreases with

aerobic exercise