muscle structure and function

Question 1

sarcolemma

Answer 1

muscle cell membrane

Question 2

sarcoplasm

Answer 2

contains nuclei that contains the genes, mitochondria, and other specialized organelles

Question 3

myofibrils

Answer 3

threadlike strands within muscle fibers

Question 4

actin

Answer 4

thin filament

Question 5

myosin

Answer 5

thick filament

Question 6

sarcomere

Answer 6

z line, m line, h zone, a band, and I band

Question 7

I band

Answer 7

lighter area in myofibril

Question 8

a band

Answer 8

darker area in myofibril

Question 9

h zone

Answer 9

center of a band

Question 10

m band

Answer 10

bisects the H zone and consists of protein structures that support the arrangement of myosin filaments

Question 11

z line

Answer 11

bisects I band and adheres to sarcolemma to provide stability

Question 12

concentric

Answer 12

reduction in the distance between z lines of the sarcomere

Question 13

isometric muscle

Answer 13

the fibers length remains unchanged, same spacing of I band and a band

Question 14

eccentric action

Answer 14

a band widens as the fiber lengthens during force generation

Question 15

motor end plate

Answer 15

pocket formed around motor neuron by sarcolemma

Question 16

neuromuscular cleft

Answer 16

short gap where Ach is released by motor neuron

Question 17

step 1

Answer 17

action potential in motor neuron has axon terminal release Ach to diffuse across the synaptic cleft and attach to specific receptor on sarcolemma

Question 18

step 2

Answer 18

action potential depolarizes the transverse tubules at sarcomeres A-I junction

Question 19

step 3

Answer 19

depolarization of t tubule releases Calcium from the sarcoplasmic reticulum

Question 20

step 4

Answer 20

calcium binds to troponin and tropomyosin in the actin filaments, releases inhibition that had previously prevented actin from attaching to myosin

Question 21

step 5

Answer 21

actin combines with myosin- myosin activates ATPase which splits ATP, this makes the crossbridge and tension

Question 22

step 6

Answer 22

ATP binds to myosin crossbridge breaking the actin and myosin bond (actin dissociates from actin) the thick and thin filaments slide past each other and the muscle shortens

Question 23

step 7

Answer 23

crossbridge continues when calcium remains high enough to inhibit troponin and tropomyosin

Question 24

step 8

Answer 24

muscle stimulation stops, calcium rapidly decreases and calcium moves back to sarcoplasmic reticulum through active transport

Question 25

step 9

Answer 25

calcium removal restores inhibitory action of troponin and tropomyosin, ATP present leaves actin and myosin in relaxed state

Question 26

fusiform/spindle shaped fibers

Answer 26

run parallel to the muscles long axis and taper at tendinous attachment

Question 27

pennate fibers

Answer 27

lie at an oblique pennation angle and allow a large number of fibers into a smaller cross-sectional area