Quiz on Motor Units and Neurotransmitters

What is the role of Pi in muscle contraction?

• Initiates the power stroke

• Binds to actin

• Provides energy for contraction

• Stabilizes the myosin head

What is actin?

• A thick filament in muscle fibers

• A neurotransmitter

• A thin filament within the myofibril of a muscle fiber

• An energy molecule

What happens to the H zone as the muscle contracts?

• It becomes larger

• It becomes smaller

• It stays the same size

• It disappears completely

What is the significance of the A band during contraction?

• It shortens

• It lengthens

• It remains the same length

• It disappears

What is the basic functional unit of a muscle fiber?

• Myofibril

• Sarcomere

• Z disk

• M line

Which component of the sarcomere is known as the thick filament?

• Actin

• Myosin

• Troponin

• Tropomyosin

How do Type IIa and IIb fibres vary?

• By colour

• By glycogen content

• By size

• By length

Fast twitch fibers have less density of:

• Mitochondria

• Capillaries

• Glycogen

• Sarcoplasmic reticulum

What is the term for a muscle contraction where the speed of contraction is constant?

• Isokinetic

• Isometric

• Isotonic

• Eccentric

What is the role of calcium ions in muscle contraction?

• They bind to myosin

• They bind to troponin

• They provide energy for contraction

• They stabilize the actin filament