05 Video Quiz A - Mech of Muscle Contraction: Intro/Sarcomere

What is the main topic discussed in the video?

• The structure of bones

• Action potential in muscle fibers

• The nervous system

• Blood circulation

What are muscle fibers primarily made of?

• Myofibrils

• Calcium

• Myosin and actin

• Neurons

What are the darker regions in a sarcomere called?

• I bands

• H zones

• A bands

• M lines

What role does the H zone play in muscle contraction?

• It contains actin

• It is where myosin heads are found

• It is where Z discs are located

• It is a region that disappears during contraction

What is the function of tropomyosin in muscle fibers?

• To bind calcium

• To block the active sites on actin

• To form myofilaments

• To connect myosin and actin

What is the sliding filament model of contraction?

• It describes how bones move

• It explains the interaction between thick and thin filaments

• It shows how muscles relax

• It focuses on the nervous system

Which protein is primarily responsible for the thick filaments?

• Actin

• Tropomyosin

• Myosin

• Calcium

What happens to the I bands during muscle contraction?

• They lengthen

• They stay the same

• They shorten

• They disappear completely

What surrounds each myofibril and regulates calcium levels?

• Sarcoplasmic reticulum

• Z discs

• A bands

• T tubules

What is the role of the M line in a sarcomere?

• It separates the A bands

• It anchors the thick filaments

• It holds the Z discs

• It connects to the T tubules