Which of the following does NOT occur in or immediately prior to a muscle contraction?
- action potential in motor neuron
- acetylcholine released into synaptic cleft
- temporary localized changes in the membrane potential of the sarcolemma and t-tubules
- sacroplasmic recticulum releases acetylcholine
- active sites on actin molecules are exposed
During contraction of a muscle, calcium ions bind to the _______.”
- actin and myosin filaments
- troponin molecule
- tropomyosin molecule
- sarcoplasmic reticulum
Which of the following is NOT a role of ionic calcium in muscle contraction?
- triggers neurotransmitter secretion
- binds with troponin
- removes contraction inhibitor
- spreads the depolarization from the neuromuscular junction to the T-tubules
The role of tropomyosin in a muscle cell is to ____.
- all to cell to relax by blocking the binding sites on actin
- facilitate the formation of cross-bridges between actin and myosin
Interactions between thick and thin filaments during muscle contraction occur in which sequence?
- “attach to actin, detach from actin, pivot in powerstroke, return or recock”
- “attach to actin, pivot in powerstroke, detach from actin, return or recock”
- “attach to actin, pivot in powerstroke, return or recock, detach from actin”
- “detach from actin,pivot in powerstroke, attach to actin, return or recock”
What is the role of calcium pump in muscle contractions?
- pump calcium out of the sarcoplasmic reticulum against its concentration gradient to initiate contractions
- remove calcium from the fluid surrounding the myofibrils to end contractions
- pump calcium into the muscle cell to stimulate the release of acetylcholine
Rigor mortis demonstrates that skeletal muscle tissue
- normally requires energy to end as well as to start a contraction
- can survive and function for some time after the heart stops beating
- “maintains powerful contractions even with no ATP, until autolysis occurs”
- all of the above