Muscle Physiology: Troponin, Tropomyosin, and Myosin Cross-Bridge Cycle

The video tutorial explains the crossbridge cycle, focusing on muscle contraction and the role of myosin and actin. It begins with an exercise to demonstrate bicep contraction, then delves into the structure of muscle cells, myofibrils, and sarcomeres. The tutorial details the crossbridge cycle, highlighting the interactions between myosin and actin, and the role of calcium ions, troponin, and tropomyosin. It concludes with an explanation of the myosin cycle and the importance of ATP in muscle contraction.

What is the initial position of the arm in the kinesthetic exercise described in the video?

• 135 degrees

• 45 degrees

• 180 degrees

• 90 degrees

What is the functional unit of a myofibril?

• Myosin

• Troponin

• Actin

• Sarcomere

What is the main protein found in thick filaments?

• Troponin

• Tropomyosin

• Myosin

• Actin

What is the significance of the M line in the sarcomere?

• It is where actin filaments attach

• It is the center line where sarcomere shortens

• It is where myosin heads detach

• It is the boundary of the sarcomere

Which protein is responsible for covering the myosin binding sites on actin at rest?

• Myosin

• Calcium

• Troponin

• Tropomyosin

What is the role of calcium ions in muscle contraction?

• They bind to actin

• They bind to ATP

• They bind to troponin

• They bind to myosin

What happens when ATP binds to the myosin head?

• Myosin binds to actin

• Calcium is released

• Crossbridge detachment occurs

• Tropomyosin covers actin

What is the result of ATP hydrolysis in the myosin cycle?

• Myosin head detaches

• Myosin head is activated

• Actin filament breaks

• Calcium binds to troponin

What is the term used to describe the movement of myosin that results in the contraction of the thin filament?

• Calcium release

• ATP binding

• Power stroke

• Crossbridge formation

Which molecule's dissociation strengthens the interaction between myosin and actin?

• ATP

• Phosphate

• Calcium

• ADP