Muscle Biology and Physiology

Question 1

What determines the speed and duration of contraction of muscles?

Answer 1

Fiber type
Type I (slow twitch): endurance, low contraction force, low speed, long duration
Type II (fast twitch): explosive, high force, high speed, short duration

Question 2

Muscle ruptures most commonly occur during what type of muscle contraction?

Answer 2

eccentric phase of isotonic exercise

Question 3

The cross-sectional area of a muscle is the factor most responsible for?

Answer 3

Force generated (maximal tension)

Question 4

What are the steps in muscle activation?

Answer 4

1) Nerve delivers signal to motor endplate
2) Ach is released, crosses synapse and binds to Ach receptors (MG lacks receptors, botox blocks Ach release)
3) Sarcoplasmic reticulum releases Ca that binds to troponin
4) Tropomycin configuration changes on thin filament which exposes actin
5) actin binds to myosin