50.5 skeletal muscle fibers

Question 1

types are classified by:

Answer 1

source of ATP or

speed of muscle contractions

Question 2

types of fibers

Answer 2

• oxidative
• glycolytic
• fast twitch
• slow twitch

Question 3

oxidative fibers

Answer 3

• get energy from aerobic respiration
• mitochondria, rich blood supply, myoglobin (oxygen storing protein)

-fatigue slower
(dark meat-migratory birds)

Question 4

myoglobin

Answer 4

oxygen storing protein in oxidative fibers-

• -binds O2 tighter then hemoglobin even
• -lets it extract O2 from blood

Question 5

glycolytic fibers

Answer 5

glycolysis for ATP
-larger diameter, less myoglobin than oxidative fibers

-fatigue fast
(white mean-)

Question 6

fast twitch fibers

Answer 6

• develop tension 2-3 times faster than slow twitch
• brief, rapid, powerful contractions
• oxidative or glycolytic fibers

Question 7

slow twitch fibers

Answer 7

• sustain long contractions
• -(muscles for posture)
• oxidative fibers-fatigue slower
• less Sarcoplasmic R and puts Ca2+ slower–so the ca2+ remains in the cytosol longer

Question 8

why do slow twitch and fast twitch have different speed of contractions?

Answer 8

-rate at which myosin heads hydrolyze (break down) ATP —causing contractions