Physiology of Muscle Contraction Flashcards
1
Q
what does a nerve impulse cause?
A
acetylcholine (ACh) to release into the synaptic cleft
- ACh binds to receptors on the motor end plate, initiating a muscle fiber impulse
2
Q
what causes calcium to leak into the sarcoplasm?
A
spread of the impulse down t-tubules
3
Q
calcium ions bind to…
A
troponin, which changes shape
4
Q
troponin moves…
A
tropomyosin, exposing active sites on actin
5
Q
myosin heads bind to…
A
actin’s active sites and form cross-bridges
- calcium = key, troponin = lock
6
Q
myosin pulls what toward the center of the sarcomere?
A
pulls actin
7
Q
what shortens a sarcomere?
A
repeating cycle of attach-pivot-detach-return
8
Q
what happens when the impulse stops?
A
- calcium ions are actively transported into the sarcoplasmic reticulum
- tropomyosin re-covers active sites
- filaments passively slide back to their relaxed state
