Module 7 HW Questions

Question 1

What skeletal muscle fiber structure contains T tubules?

Answer 1

sarcolemma

Question 2

What skeletal muscle fiber structure stores intracellular calcium ions?

Answer 2

sarcoplasmic reticulum

Question 3

What skeletal muscle fiber structure is segmented by sarcomeres?

Answer 3

myofibrils

Question 4

What skeletal muscle fiber structure is the smallest contractile unit of a muscle fiber?

Answer 4

sarcomeres

Question 5

What skeletal muscle fiber structure has both actin and myosin?

Answer 5

myofilaments

Question 6

What skeletal muscle fiber structure is a thick myofilament with heads?

Answer 6

myosin

Question 7

What skeletal muscle fiber structure is a thin myofilament with myosin binding sites?

Answer 7

actin

Question 8

What skeletal muscle fiber structure attaches actin to the sarcolemma?

Answer 8

dystrophin

Question 9

What category of muscle contraction does not change the length of the muscle?

Answer 9

isometric

Question 10

Which type of muscle contraction causes the muscle to lengthen?

Answer 10

eccentric

Question 11

Which category of muscle contraction causes the muscle to change length?

Answer 11

isotonic

Question 12

What type of muscle contraction causes the muscle to shorten?

Answer 12

concentric

Question 13

Which protein covers myosin binding site in the relaxed state of a muscle cell?

Answer 13

tropomyosin

Question 14

Which protein hold tropomyosin in place during the resting state of a muscle cell?

Answer 14

troponin

Question 15

How many APs does a motor neuron have to send to cause a muscle cell to contract?

Answer 15

1

Question 16

Do all local motor endplate depolarization at a NMJ generate an AP in the muscle cell?

Answer 16

yes

Question 17

How does the sarcolemma propagate an AP?

Answer 17

-opens voltage gated Na channels
-peak
-closes voltage gated Na channels and opens voltage gated K+ channels

Question 18

Which ion depolarizes the motor end plate of a NMJ?

Answer 18

sodium

Question 19

What event causes voltage gated calcium channels to open on the sarcoplasmic reticulum?

Answer 19

AP moving down the T tubules

Question 20

What causes an increase in intracellular calcium in skeletal muscle?

Answer 20

opening of voltage gated calcium channels in the SR

Question 21

What does calcium bind to in order to expose myosin binding sites?

Answer 21

troponin

Question 22

What event begins the contraction of a muscle fiber?

Answer 22

cross bridge formation

Question 23

What causes the myosin head to detach from the actin myofilament?

Answer 23

ATP binds to myosin

Question 24

What is the role of ATP in the cross bridge formation?

Answer 24

energizes the myosin head

Question 25

What does calcium bind to inside the SR?

Answer 25

calsequestrin

Question 26

What specific type of receptors in the T tubules must open to release the calcium from the SR?

Answer 26

ryanodine

Question 27

How long can a muscle cell contraction continue?

Answer 27

for as long as intracellular calcium ions remain high and sufficient ATP available

Question 28

What must happen for a muscle cell to relax?

Answer 28

calcium must be pumped out of the cytoplasm and back into the SR

Question 29

What is the sliding filament theory?

Answer 29

the action of actin and myosin sliding across each other

Question 30

What structure shortens in a muscle cell contraction?

Answer 30

sarcomere

Question 31

Which antagonistic function do curare poisions and drugs have at the NMJ?

Answer 31

blocks ACh receptors on the motor endplate

Question 32

What antagonistic effect does botulism toxins have on a motor neuron at the NMJ?

Answer 32

decreases or prevents ACh release

Question 33

How does hypocalcemia affect somatic motor neurons?

Answer 33

can spontaneously generate APs

Question 34

How does hypocalcemia affect skeletal muscle?

Answer 34

causes fasciculations and or muscle twitches

Question 35

What is a motor unit?

Answer 35

a motor neuron and all the muscle fibers it innervates

Question 36

What is muscle cell recruitment?

Answer 36

more and more muscle fibers to contract to increase the strength of the whole muscle

Question 37

What is summation of muscle contraction?

Answer 37

adding together individual twitch contractions

Question 38

What is a tetanic contraction?

Answer 38

successive frequent contractions that causes a smooth continuous contraction

Question 39

How does the body maintain muscle tone while a whole muscle is at rest?

Answer 39

intermittent and alternating stimulation of different motor units

Question 40

How does regular stretching affect the number of sarcomeres within a muscle fiber?

Answer 40

increases their number