Unit 6

Question 1

Neuromuscular junction

Answer 1

site where a motor neuron’s terminal meets the muscle fiber

Question 2

Action potential

Answer 2

a special type of electrical signal that can travel along a cell membrane as a wave. This allows a signal to be transmitted quickly over long distances.

Question 3

depolarize

Answer 3

the membrane potential of the muscle fiber becomes less negative (closer to zero.)

Question 4

a specialized type of smooth endoplasmic reticulum organelle

Answer 4

sarcoplasmic reticulum (SR

Question 5

a molecule that can store energy in its phosphate bonds and is more stable than ATP.

Answer 5

creatine phosphate

Question 6

an anaerobic (non-oxygen-dependent) process that breaks down glucose (sugar) to produce ATP

Answer 6

glycolysis

Question 7

the breakdown of glucose or other nutrients in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP

Answer 7

Aerobic respiration

Question 8

Isotonic contractions

Answer 8

where the tension in the muscle stays relatively constant, a load is moved as the length of the muscle changes

Question 9

concentric contraction

Answer 9

involves the muscle producing tension and shortening to move a load. An example of this is the contraction of the biceps brachii muscle when a hand weight is brought upward toward the body

Question 10

eccentric contraction

Answer 10

occurs when the muscle tension produced is less than the load and a muscle lengthens while under tension. This type of contraction is observed when the same hand weight is lowered in a slow and controlled manner by the biceps brachii.

Question 11

Isometric contraction

Answer 11

occurs when a muscle produces tension without a change in muscle length.

Question 12

A single action potential from a motor neuron will produce a single contraction in the muscle fibers innervated by the motor neuron

Answer 12

twitch

Question 13

wave summation

Answer 13

A graded muscle response works as follows: if the fibers are stimulated while a previous twitch is still occurring, the second twitch will be stronger.

Question 14

incomplete tetanus

Answer 14

the muscle goes through quick cycles of contraction followed by a short relaxation phase

Question 15

complete tetanus

Answer 15

the stimulus frequency is so high that the relaxation phase disappears completely, contractions become continuou

Question 16

treppe

Answer 16

The muscle tension increases in a graded manner that to some looks like a set of stairs.

Question 17

latent period of twitch

Answer 17

the action potential is being propagated along the sarcolemma and Ca++ ions are released from the sarcoplasmic reticulum. This is the phase during which excitation and contraction are being coupled but contraction has yet to occur.

Question 18

contraction phase of twitch

Answer 18

occurs as the muscle generates increasing levels of tension; the Ca++ ions in the sarcoplasm have bound to troponin, tropomyosin has shifted away from actin-binding sites, cross-bridges have formed, and sarcomeres are actively shortening.

Question 19

relaxation phase of twitch

Answer 19

when tension decreases as Ca++ ions are pumped out of the sarcoplasm back into the sarcoplasmic reticulum, returning the muscle fibers to their resting state.