043 The details of Muscle Contraction

In this episode, Leslie Samuel explores the details of muscle contraction, focusing on the sarcomere, myosin, and actin. The video explains the six steps of muscle contraction, including calcium release, binding of myosin heads to actin, and the power stroke. The process is detailed with explanations of the roles of ATP, troponin, and tropomyosin. The episode concludes with a recap of the steps and an invitation for questions.

What is the functional unit of muscle contraction?

• Myofibril

• Ligament

• Sarcomere

• Tendon

Which two proteins are crucial for regulating the binding of myosin heads to actin?

• Calcium and ATP

• Tropomyosin and Troponin

• Myoglobin and Hemoglobin

• Actin and Myosin

What triggers the release of calcium from the terminal cisternae?

• Protein synthesis

• ATP synthesis

• Nerve impulse

• Muscle relaxation

What happens during the power stroke in muscle contraction?

• ATP is synthesized

• Calcium binds to tropomyosin

• Actin slides over myosin

• Myosin heads detach from actin

What causes the myosin head to detach from the actin filament?

• Binding of a new ATP molecule

• Release of calcium ions

• Binding of ADP

• Hydrolysis of ATP

How is the myosin head re-energized for another cycle of contraction?

• By releasing calcium

• By binding to tropomyosin

• By hydrolyzing ATP

• By binding to actin

What happens to calcium ions at the end of the muscle contraction cycle?

• They are converted into ATP

• They are pumped back into the terminal cisternae

• They are released into the bloodstream

• They remain bound to troponin