Question

Indicate whether each statement regarding muscle relaxation is true or false.

1. As long as potassium remains in the muscle, the tropomyosin will stay uncovered.  (Click to select)  True  False
2. Energy is needed to make muscles relax.  (Click to select)  True  False
3. Relaxation occurs when Ca²⁺ is transported back into the sarcoplasmic reticulum.  (Click to select)  True  False
4. The active transport of Ca²⁺ into the sarcoplasmic reticulum requires ATP.  (Click to select)  True  False

Answer 1

Answer

1) As long as potassium remains in the muscle, the tropomyosin will stay uncovered. --- FALSE

• Calcium ions are responsible for removing tromomyosin from the binding sites on actin.
• Hence, presence of calcium ions will ensure that tropomyosin cannot cover the binding sites.

2) Energy is needed to make muscles relax. --- TRUE

• In order for muscle to get relaxed, calcium ions must be pumped back into sarcoplasmic reticulum.
• This process requires ATP.

3) Relaxation occurs when Ca²⁺ is transported back into the sarcoplasmic reticulum. --- TRUE

• Removing calcium from sarcoplasm causes tropomyosin to cover the binding sites on actin.
• Cross-bridge cannot form and muscle relaxes.

4) The active transport of Ca²⁺ into the sarcoplasmic reticulum requires ATP. ---- TRUE

• Active transport is transport of a sunstance against its concentration gradient.
• It requires energy in the form of ATP.