5.4 Sliding Filaments and Physiology of Muscle Contraction

This is the scary one. It's super long

A nerve impulse reaches the axon terminal, which triggers __________ to enter the axon terminal.

Calcium ions

You are drawing a diagram of a neuron as you study for your exam. Which best describes the motor unit ratio of this movement in your fingers?

7

• this is a fine motor movement so the ratio will be very small, about 1 motor neuron innervating less than 10 muscle fibers

What protein must be removed from the thin filament to allow myosin to bind?

Tropomyosin

The vesicles in the axon terminals of motor neurons contain _____.

acetylcholine

True or False: Sarcomeres are separated from each other by z discs.

True

The protein that covers actin's myosin binding sites is called _____

tropomyosin

The presence of ATP bound to myosin leads to _____.

Myosin detaching from actin

_____ is the neurotransmitter that triggers sodium to enter the muscle fiber and initiate depolarization.

Acetylcholine

Which of the following act to return the sarcomere to its resting length?

• Gravity

• Opposing muscle contractions

• Elastic forces