Filaments and Fatigue

Question 1

Muscle tension

Answer 1

force created by muscle

Question 2

load

Answer 2

weight (force/ resistance) that opposes contraction

Question 3

contraction

Answer 3

creation of tension in muscle by sacromere shortening

Question 4

relaxation

Answer 4

release of tension in muscle

Question 5

twitch

Answer 5

a single contraction-relaxation cycle

Question 6

What are the 3 steps leading u to muscle contraction

Answer 6

events at neuromuscular junction, excitation-contraction coupling, and contraction-relaxation cycle

Question 7

Latent Period (in reference to contraction)

Answer 7

contraction has not yet begun

Question 8

Why is the contraction of skeletal muscle later than the action potential?

Answer 8

because it takes time for calcium levels to rise

Question 9

How do muscle twitches differ from action potentials

Answer 9

because they can summate and do not have a refractory period

Question 10

define a single twitch (time-tension relationships)

Answer 10

muscle relaxes completely between stimuli

Question 11

Define summation (time-tension relationships)

Answer 11

stimuli closer together do not allow muscle to relax fully

Question 11

If we space excitation closer in time, how does this affect the tension of the muscle twitch

Answer 11

our tension would increase

Question 12

Ways we can increase force/muscle tension? (4)

Answer 12

stimulate more motor units, stimulate larger motor units, stimulate more fast twitch fibers, stimulate fibers faster and closer together (summation=greater force)

Question 13

Tetanus

Answer 13

high rate of stimulation (sustained muscle contraction from sustained stimulus)

Question 14

Unfused tetanus

Answer 14

stimuli are far enough apart to allow muscle to relax slightly between stimuli; near max contraction (not quite there), you can still see little bits of contraction and relaxation

Question 15

Complete (fused) tetanus

Answer 15

steady tension (w/o relaxation), but then fatigue causes muscle to lose tension despite continuing stimuli (completely max out our contraction)

Question 16

in skeletal muscle, what pump primarily gets rid of calcium?

Answer 16

SERCA pump

Question 17

Where is the SERCA pump located in the skeletal muscle and cardiac muscle?

Answer 17

sarcoplasmic reticulum

Question 18

Depletion Theory

Answer 18

if we run out of ATP, glycogen, or phosphocreatin we cannot have a contraction

Question 19

isometric contraction

Answer 19

contractions create force without moving the load

Question 20

isotonic contractions

Answer 20

create force and move load

Question 21

describe the sacromeres and the elastic elements in isometric contraction

Answer 21

sarcomeres shorten while the elastic elements stretch (that is why there is little change in overall length)

Question 22

isotonic concentric action is…

Answer 22

a shortening action (bringing a weight toward your body)

Question 23

the isotonic eccentric action is…

Answer 23

the lengthening action (bringing a weight away from your body)

Question 24

Nebulin

Answer 24

helps align actin

Question 25

Titin

Answer 25

provides elasticity and stabilizes myosin to the Z disk (springy and it is an elastic element)

Question 26

spindles do what (reflex arc)

Answer 26

respond to stretch

Question 27

When we have a length-tension graph, why is it that the most decreased length has 0 tension (force)?

Answer 27

because it is maximally contracted, there are portions of actin that do not have a myosin partner and actin is also blocking other regions of actin; therefore, due to all these factors it cannot contract (= 0 force)

Question 28

When we have a length-tension graph, why is it that the most increased length has 0 tension (force)?

Answer 28

because we maximally expanded it; myosin cannot grab the actin, so the muscle cell cannot contract