Muscle Physiology Quiz

What is the functional unit of skeletal muscle?

• Sarcolemma

• Sarcomere

• Myofilament

• Myofibril

Which protein blocks myosin-binding sites on actin when the muscle is relaxed?

• Actin

• Myosin

• Troponin

• Tropomyosin

What is the role of the sarcoplasmic reticulum in muscle contraction?

• Forms cross-bridges

• Transmits electrical impulses

• Stores and regulates intracellular Ca

• Anchors thin filaments

What happens during the power stroke of crossbridge cycling?

• Myosin head attaches to actin

• Myosin head pulls thin filament toward the center of the sarcomere

• ATP binds to myosin head

• Myosin head resets

Which structure acts as a voltage sensor in muscle fibers?

• M line

• Sarcoplasmic reticulum

• Z line

• T-tubule integral proteins

What is the resting membrane potential of a skeletal muscle fiber?

• -50 mV

• -30 mV

• -90 mV

• -70 mV

Tags

NGSS.HS-PS3-5

Which molecule binds to the myosin head to cause its release from actin?

• ATP

• Ca2+

• Pi

• ADP

Tags

NGSS.HS-LS1-7

What is the role of the terminal cisternae in muscle contraction?

• Stores ATP

• Forms cross-bridges

• Stores and releases Ca

• Anchors thick filaments

Which of the following describes the I band in a myofibril?

• Anchor for thin filaments

• Thick myofilaments only

• Light area; thin myofilaments only

• Dark area; extends length of the thick filaments