Karius ibook for Excitation and Contraction of Smooth Muscle

Question 1

Excitation contraction coupling in skeletal muscle: sequential events

Answer 1

action potential initiated by end plate potential induced by activation of nAChR on motor end plate —-> AP travels down sarcolemma —> AP down T tubule —> Depolarization causes conformation change in DHP –> DHP causes conformation change in ryanodine receptor —> ryanodine opens SR and Ca diffuses out –> Ca diffuses to myofibrils —> cross bridge cycling

Question 2

Two fuels used to drive skeletal muscle contraction

Answer 2

glucose and free fatty acid (ffa)

Question 3

at low levels of work, what is the body’s preferred energy source?

Answer 3

ffa, leads to a lot of energy

Question 4

at high levels of work, the preferred energy source is

Answer 4

glucose

Question 5

What is the “backup system” at the myofibrils that help with ATP production?

Answer 5

creatine phosphate: serves as a phosphate donor for ADP to become ATP

ATP is “sacrificed” near the mito to produce a phosphorylated ATP at the margins of the cell
CrP then diffuses to the myofibrils

Question 6

Chemistry of SM: Thin filaments

Answer 6

2x as much as skeletal muscle