Chapter 7: The Muscular System

Question 1

Epimysium

Answer 1

outermost layer of collagen fibers that surrounds the entire skeletal muscle

Question 2

Perimysium

Answer 2

Connective tissue surrounding a fascicle

Question 3

Fascicle

Answer 3

bundle of muscle fibers

Question 4

muscle fiber

Answer 4

a single muscle cell

Question 5

Endomysium

Answer 5

surrounds each muscle fiber; ties adjacent muscle fibers together

Question 6

sarcolemma

Answer 6

muscle cell membrane

Question 7

sarcoplasm

Answer 7

cytoplasm of a muscle cell

Question 8

Transverse tubules (T-tubules)

Answer 8

openings scattered across the surface of the sarcolemma that lead into terminal Cisternae

Important for initiation of excitatory process to release Ca2+

Question 9

myofibrils

Answer 9

long, cylindrical protein structures that make up muscle fibers; bundles of myofilaments

Question 10

myofilaments

Answer 10

make up myofibrils; constructed from proteins, principally myosin and actin

Question 11

sarcoplasmic reticulum

Answer 11

specialized smooth endoplasmic reticulum, releases calcium on demand when the muscle fiber is stimulated to contract

Question 12

A band

Answer 12

contains thick filaments (myosin)

Question 13

I band

Answer 13

thin filaments only (actin); shortens during contraction

Question 14

synaptic cleft

Answer 14

The narrow gap that separates the presynaptic neuron from the postsynaptic cell

Question 15

motor unit

Answer 15

a motor neuron and all the muscle cells it stimulates

Question 16

recruitment

Answer 16

the activation of more and more motor units

Question 17

isotonic contraction

Answer 17

muscle shortens or lengthens because muscle tension exceeds load
-concentric or eccentric

Question 18

isometric contraction

Answer 18

no shortening; muscle tension increases but does not exceed load

Question 19

creatine phosphate

Answer 19

energy storage molecule used by muscle tissue; the phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly

Question 20

Anaerobic

Answer 20

without oxygen; the length of time that muscle contractions can be supported by glycolysis and existing energy reserves of ATP and CP

Question 21

aerobic

Answer 21

with oxygen; the length of time that a muscle can continue to contract while being supported by mitochondrial activities

Question 22

terminal cisternae

Answer 22

enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules; store excess calcium

Question 23

glycolysis

Answer 23

the breakdown of glucose by enzymes, releasing energy and pyruvic acid

Question 24

Myoglobin

Answer 24

oxygen-storing, red-pigmented protein in slow-twitch muscle fibers

Question 25

Masseter

Answer 25

chewing muscle

Question 26

Buccinator

Answer 26

“trumpeter”; compresses cheek

Question 27

cross bridges

Answer 27

myosin head; binds to an active site and pivots toward the center of the sarcomere, pulling the thin filament in that direction

Question 28

summation

Answer 28

the addition of one twitch to another

Question 29

incomplete tetanus

Answer 29

muscle produces almost peak tension during rapid cycles of contraction and relaxation

Question 30

complete tetanus

Answer 30

occurs when the rate of stimulation is increased until the relaxation phase is completely eliminated, producing maximum tension

Question 31

muscle fatigue

Answer 31

caused by exhaustion of energy reserves or accumulation of H+ ions in the (EC) fluid; muscle can no longer contract despite continued neural stimulation

Question 32

origin

Answer 32

beginning of muscle; remains stationary

Question 33

insertion

Answer 33

The attachment of a muscle tendon to a moveable bone or the end opposite the origin

Question 34

hamstring

Answer 34

biceps femoris, semitendinosus, semimembranosus

Question 35

muscle naming

Answer 35

orientation of muscle fibers, structural features, by shape/length/size/visibility from surface (superficial vs. deep)

Question 36

sarcomere

Answer 36

contractile units within myofibrils; the smallest functional unit of a muscle