Muscle Physiology

Question 1

muscle cell

Answer 1

muscle fiber

Question 2

cell membrane

Answer 2

sarcolemma

Question 3

cytoplasm

Answer 3

sarcoplasm

Question 4

modified endoplasmic reticulum (ER)

Answer 4

sarcoplasmic reticulum

Question 5

neuromuscular junction

Answer 5

when a motor neuron stimulates a muscle cell to contract by causing a chemical synapse between the nerve terminal and motor end plate

Question 6

sliding filament theory

Answer 6

contraction of a muscle when the thin filament slides past the thick filament; sarcomere shortens and the thin and thick filaments overlap

Question 7

actin

Answer 7

major component of the thin filament; each actin subunit has a specific binding site for the myosin cross bridge

Question 8

tropomyosin

Answer 8

regulatory protein of the thin filament entwined around actin and covers myosin binding sites

Question 9

troponin

Answer 9

attached to and spaced periodically on tropomyosin strand; exposes the binding sites on actin

Question 10

end-plate potential (EEP)

Answer 10

caused by depolarization of the muscle fiber membrane

Question 11

muscle twitch

Answer 11

a single contraction-relaxation cycle of the muscle

Question 12

single twitch

Answer 12

muscle relaxes completely between stimuli

Question 13

summation

Answer 13

muscle does not relax completely as stimuli are close together

Question 14

summation leading to tetanus

Answer 14

muscle only relaxes slightly between stimuli that are very close together

Question 15

sources of glucose

Answer 15

enters the muscle cell directly from the blood or is produced by hydrolysis of glycogen stored in the muscle cell

Question 16

sources of oxygen

Answer 16

enters the muscle cell directly from the blood or is stored in myoglobin

Question 17

isometric contraction

Answer 17

muscle exerts force without changing length; plank holds and wall sits

Question 18

isotonic/dynamic contraction

Answer 18

muscle exerts force by changing length

Question 19

concentric contraction

Answer 19

muscle shortens during force production; bicep curls and sit-ups

Question 20

eccentric contractions

Answer 20

muscle lengthens during force production; squats and triceps extensions

Question 21

muscle spindle

Answer 21

changes muscle length; contains actin and myosin for contraction

Question 22

golgi tendon organ (GTO)

Answer 22

monitors tension development, prevents damage during excessive force, stimulation results in reflex relaxation