ADAM Unit 2

Question 1

t tubule

Answer 1

invaginations of the sarcolemma penetrating deep into the interior of the muscle cell

Question 2

synaptic cleft

Answer 2

the space between the axon terminal and the motor end plate

Question 3

sarcolemma

Answer 3

the muscle cell membrane

Question 4

synaptic vesicles

Answer 4

structures within the axon terminal that contain the neurotransmitter acetylcholine

Question 5

sacromere

Answer 5

the contractile unit of the muscle cell that extends from z line to the next

Question 6

terminal cisternae

Answer 6

structures within skeletal muscle cells that serve as a reservoir of calcium ions

Question 7

motor end plate

Answer 7

a folded region of the sarcolemma at the neuromuscular junction

Question 8

motor neuron axon

Answer 8

the elongated process of a nerve cell that carries impulses away from the nerve cell body to the muscle

Question 9

what happens when a muscle cell contracts

Answer 9

thin filament slide past thick filaments and the sarcomere shortens

Question 10

myosin

Answer 10

the protein that composes the major portion of the thick filament and includes two heads and a tail region

Question 11

actin

Answer 11

the protein that composes the major portion of the thin filament

Question 12

tropomyosin

Answer 12

a protein molecule that entwines around actin and blocks the myosin binding sites; prevents cross bridge cycling until it moves aside

Question 13

troponin

Answer 13

a three polypeptide complex that binds calcium ions and drags tropomyosin off the myosin binding sites on actin

Question 14

ATP

Answer 14

adenosine triphosphate, an organic molecule that stores and releases chemical energy within the cell

Question 15

calcium ions

Answer 15

found in the extracellular fluid and terminal cisternae and can enter the cytosol where they play an important role in many processes such as muscle contraction and release of neurotransmitters

Question 16

3 roles played by ATP in muscle contraction

Answer 16

energizing the power stroke of the myosin cross bridge
disconnecting the myosin head from the binding site on actin at the conclusion of the power stroke
actively transporting calcium ions into the sarcoplasmic reticulum

Question 17

neuromuscular junction

Answer 17

the place where a motor neuron stimulates a muscle cell

Question 18

resting membrane potential

Answer 18

the voltage that exists across a cell’s plasma membrane when the cell is at rest; cell interior is relatively more negative than the cell exterior

Question 19

action potential

Answer 19

an electrical signal consisting of the depolarization and subsequent repolarization of a nerve or muscle cell membrane and functions as a signal to initiate an activity such as a muscle contraction

Question 20

depolarization

Answer 20

a decrease in the negative resting membrane potential (the voltage that exists across the plasma membrane)

Question 21

motor neuron

Answer 21

a single cell that extends from the brain or spinal cord to a muscle or gland

Question 22

when the action potential arrives at the axon terminal, voltage-gated calcium channels open and then

Answer 22

calcium ions enter the axon terminal

Question 23

presence of calcium ions in the axon terminal cause

Answer 23

synaptic vesicles fuse with the membrane

Question 24

acetylcholine binds to the receptors sites on the motor end plate

Answer 24

calcium ions are pumped out of the axon terminal

Question 25

acetylcholine diffuses away from its receptor site, the ion channel closes

Answer 25

acetylcholine is then broken down by acytelcholinesterase

Question 26

an action potential is generated which does

Answer 26

propagates along the sarcolemma in all directions and down the t- tubules

Question 27

an action potential causes

Answer 27

the release of calcium ions from the terminal cisternae into the cytosol

Question 28

the presence of calcium ions in the cytosol triggers

Answer 28

contraction of the muscle cell

Question 29

what does action attach to

Answer 29

myosin and troponin

Question 30

what does myosin attach to

Answer 30

actin and ATP

Question 31

what does troponin attach to

Answer 31

actin, tropomyosin, calcium ions