Skeletal Muscle Characteristics-Lecture 16 Exam 3

Question 1

Cross-bridge Cycling uses ATP to Cause the Muscle to Contract

Answer 1

-During crossbridge cycling, binds to myosin head (contraction)
-Pumps Ca2+ back into SR (relaxation)
-Na+/K+/ATPase pump (initiation of contraction)

Question 2

ATP Storage in Muscle Contraction

Answer 2

-Muscle at rest: ATP + creatine -> (creatine kinase) ADP + phosphocreatine
-Muscle at work: Phosphocreatine + ADP -> (creatine kinase) creatine + ATP

Question 3

Creatine Kinase

Answer 3

An enzyme that catalyzes a reversible reaction to “store” ATP

Question 4

Slow-Twitch Oxidative (Type I) Fibers

Answer 4

-Low intensity, long-lasting activities
-More resistant to fatigue
-Contractions last long, slow to reuptake Ca2+ to SR
-Aerobic metabolism (oxidative phosphorylation)
-Require large amounts of O2 -> high amounts of ATP
-Many mitochondria
-Red fibers -> high myoglobin to bring more O2

Question 5

Fast-Twitch
Oxidative-Glycolytic (Type IIa)

Answer 5

-Fast, powerful actions
-Generate more power
-High myosin ATPase activity
-Contraction send quickly, reabsorb Ca2+ to SR faster