Name: ____________________________________________________________ Date: __________ Hour: ___________
Elaboration Questions: Contraction of a Skeletal Muscle
1. Use the pictures below to explain how a nerve impulse results in a muscle contraction. Label the
components involved and label what is happening. Make sure to include the following words: arriving action
potential, ACh, mitochondria, vesicle, synaptic terminal, synaptic cleft, ACh receptor site, and motor end
plate. Use arrows to help explain the process and try to label all the steps discussed in class. Use notes and
pages 200-201 as a guide.
2. Use the pictures below to explain the process of muscle contraction at the level of the sarcomere. Label all
components involved and label what is happening. Make sure you label the following: thin filaments, thick
filaments, Z line, M line, A band, I band, myosin, actin, and myosin head. Make sure to use arrows to better
explain the process.
QUESTIONS:
3. Listed below are the steps in the contraction of a muscle. Put them in the correct order.
_____ Acetylcholine binds to the receptors on the motor end plate on sarcolemma
_____ Acetylcholine diffuses across the synaptic cleft
__5__ Acetylcholine released into synaptic cleft
_____ Action potential generated
_10__ Action potential moves along the sarcolemma
_____ Action potential moves down into fiber along transverse tubules
_____ Action potential moves into the sarcoplasmic reticulum
_____ ATP binds to myosin heads
_____ Calcium ions enter synaptic bulb
_____ Calcium ions expose binding sites on actin
_20__ Cross bridges between myosin heads and actin break
__1__ Depolarization of axon cell membrane reaches synaptic bulb
_____ Motor end plate on sarcolemma depolarizes
_15__ Myosin heads bind to actin forming cross bridges
_____ Myosin heads change shape
_____ Myosin heads lose ADP and P
_____ Myosin heads pull actin toward center of sarcomere causing sarcomere to shorten
_____ Sarcomere returns to original shape and muscle relaxes
_____ Sarcoplasmic reticulum releases calcium ions
_____ Vesicles containing acetylcholine fuse with cell membrane of synaptic bulb
_____ Vesicles containing acetylcholine migrate to cell membrane of synaptic bulb
4. Match the description with the correct structure.
A. Acetylcholine
C. Motor end plate
E. Synaptic cleft
B. Acetylcholinesterase
D. Neuromuscular junction
F. Synaptic knob (bulb)
______ Specialized intercellular connection between a neuron and a skeletal muscle fiber
______ End of axon of a motor neuron; contains vesicles filled with acetylcholine
______ Narrow space that separates the synaptic knob from the sarcolemma
______ Portion of the sarcolemma with acetylcholine receptors
______ Neurotransmitter; released by a neuron; can cause changes in other cells
______ Enzyme that breaks down acetylcholine