Skeletal Muscle Contraction - An In-Depth Look

Question 1

Whole muscle contraction

Answer 1

Distance between insertion (end of muscle that attaches to the freely moving bone) and origin (end of muscle that attaches to the “fixed” bone in the joint) shortens
Flexion (decreases joint angle)
Extension (increases joint angle)

Question 2

Why is ATP needed for contraction? (4)

Answer 2

• ATP binding to cross-bridge: myosin detaches from actin - prevent rigor mortis
• ATP hydrolysis: energy needed for powerstroke
• Drives the Ca2+ pump to return Ca to the SR
• Muscles does NOT have extensive ATP-stores (needs to make it as fast as it is using it)

Question 3

Generate action potentials (most common)

Answer 3

Twitch fibers

Question 4

Muscle fiber classified based on myosin ATPase type

Answer 4

Slow oxidative
Fast oxidative glycolytic
Fast glycolytic

Question 5

Mammalian muscles are ____

Answer 5

Mixed fiber type