Exam #3 Chapter 9 Muscular System (Histology & Physiology) part 2

Question 1

what is the 2nd step of the cross-bridge cycling to occur?

Answer 1

1) the myosin head pivots
2) releases ADP
3) pulls the thin filament towards the M line (power stroke) (PULL)

Question 2

what happens to the calcium ions during muscle relaxation?

Answer 2

they are pumped back into the sarcoplasmic retiuclum using ATP

Question 3

what phases occurs after the stimulus during the muscle twitch in the lab?

Answer 3

the short lag phase, contraction phase and a relaxation phase.

Question 4

during stimulus frequency and muscle contraction in a lab what does higher frequency stimulations produce?

Answer 4

incomplete tetanus with higher tension but partial relaxations between stimulations

Question 5

what type of muscle fiber does treppe occur in?

Answer 5

one that has rested for a prolonged period

Question 6

what type of motor units do muscles that produce delicate movements have?

Answer 6

ones with fewer fibers than large postural muscles that produce powerful, less controlled movements

Question 7

What are all cells and what do they have?

Answer 7

polarized and they have a resting membrane potential that can be measured

Question 8

if there is an increasing stimulus at a low frequency what is there?

Answer 8

a gradual increase in tension above the threshold stimulus to a maximal stimulus

Question 9

during muscle frequency and contraction in a lab how does our nervous system stimulate muscles?

Answer 9

at a high frequency producing complete tetanus and recruits enough motor units to accomplish the task

Question 10

when is the only time myosin heads can generate force?

Answer 10

in the area of overlap

Question 11

while producing a muscle twitch in a lab what does a single stimulus produce?

Answer 11

a brief contraction and relaxation generating some tension (force)

Question 12

what does the force a single fiber generates depends on?

Answer 12

the rate of action potential and the fiber length

Question 13

how is the muscle tone produced?

Answer 13

involuntarily when one is awake

Question 14

why does excitation-contraction coupling occur?

Answer 14

because of the anatomical association between the T tubules and the sarcoplasmic reticulum.

Question 15

what does the membrane cause in and out of the cell?

Answer 15

more negative ions in the cell and more positive ions outside the cell

Question 16

after the steps of excitation-contraction coupling occur what then occurs?

Answer 16

the steps of cross-bridge cycling now produce a movement

Question 17

what does the active tension curve show?

Answer 17

the force generated at different muscle lengths

Question 18

during muscle frequency and muscle contraction in a lab how is an increase in tension achieved?

Answer 18

through multiple-wave summation

Question 19

what does a single motor neuron innervate?

Answer 19

multiple muscle fibers that are called a motor unit and function together

Question 20

what is the relaxation phase?

Answer 20

the time during which relaxation occurs

Question 21

what is excitation-contraction coupling?

Answer 21

the steps between an action potential in the sarcolemma and contraction

Question 22

if a muscle is stimulated with a constant stimulus at a low frequency what is there?

Answer 22

a small increase in the tension generated (treppe)

Question 23

what is the 3rd step of the Excitation-contraction coupling to occur?

Answer 23

the action potential n the T Tubule caused a reason of calcium from voltage-regulated channels in the the terminal cisternae

Question 24

why do sarcomeres generetate little or no force when it is stretched too much?

Answer 24

because there is little or no overlap

Question 25

when do sarcomeres generate maximum force?

Answer 25

at an optimal length with maximum overlap

Question 26

what are our muscles generally near?

Answer 26

the optimal sarcomere length

Question 27

what is an action potential?

Answer 27

a rapid and change to the resting membrane potential

Question 28

during stimulus frequency and muscle contraction in a lab what does low frequency stimulation produce?

Answer 28

twitches with little tension

Question 29

what does there need to be in order for the cycle of cross-bridge cycling to occur?

Answer 29

Calcium needs to be present and there needs to be available ATP

Question 30

what is occurring during isometric contractions?

Answer 30

force is generated but the muscle length does NOT change

Question 31

what does muscle tone prepare the muscle for?

Answer 31

contraction and steadies the body

Question 32

what is the first step in contraction?

Answer 32

when a muscle fiber is stiumulated to produce an action potential in the sarcolemma at the neuromuscular junction

Question 33

what happens at the neuromuscular junction?

Answer 33

a muscle fiber is stimulated to produce an action potential in the sarcolemma

Question 34

after death do cells have a membrane potential that can be measured?

Answer 34

no

Question 35

what happens when no more action potentials come down the somatic motor neuron axon?

Answer 35

all the ACH is degraded, stopping action potentials in the sarcolemma.

Question 36

what happens to the tropomyosin during muscle relaxatoin?

Answer 36

it's rolled back on the myosin binding sites of actin and contraction ceases

Question 37

what are the two types of isotonic contractions?

Answer 37

1) concentric isotonic contractions | 2) eccentric isotonic contractions

Question 38

what is the lag (latent) phase?

Answer 38

the gap between the time of the stimulus application to the motor neuron and the beginning of the contraction

Question 39

what is the 3rd step of the cross-bridge cycling?

Answer 39

An ATP binds to the myosin head and it detaches from the action (RELEASE)

Question 40

why does the voltage read as a negative number?

Answer 40

because the inside is negative compared to the outside

Question 41

what is multiple-wave summation?

Answer 41

the adding of calcium releases together

Question 42

why is little or no force generated in a sarcomere when it is compressed too much?

Answer 42

since the thin filaments overlap or the thick filaments hit the Z disc

Question 43

what are eccentric isotonic contractions?

Answer 43

the muscle lengthens

Question 44

what is muscle tone?

Answer 44

the contraction of a few motor units when the muscle is not contracting

Question 45

what is the 2nd step of the Excitation-contraction coupling to occur?

Answer 45

next to the T Tubules are 2 large sections of the sarcoplasmic reticulum called terminal cisternae that form a triad with the T Tubule

Question 46

what is the contraction phase?

Answer 46

the time during which contraction occurs

Question 47

what is the fourth and last step of the Excitation-contraction coupling to occur?

Answer 47

the calcium binds to troponin and moves trypomyosin off the actin active sites to which myosin heads can now bind

Question 48

what is the first step of the Excitation-contraction coupling to occur?

Answer 48

the action potential in the sarcolemma travels down the T Tubules

Question 49

what is the 4th step of the cross-bridge cycling?

Answer 49

the myosin head hyrolyzes ATP into ADP and (P) which remain attached and the head recocks (EXTEND)

Question 50

what type of force does a sarcomere generate when it is compressed too much?

Answer 50

little or no force

Question 51

during cross-bridge cycling what happens when tropomyosin is moved?

Answer 51

when tropomyosin is moved the myosin head has an attached ADP and an attached inorganic phosphate (P)

Question 52

in neurons and muscle fibers what are actions potentials always?

Answer 52

the same

Question 53

during stimulus frequency and muscle contraction in a lab at higher frequency stimulations how is complete tentanus achieved?

Answer 53

with high, steady tension generated by high calcium levels obtained

Question 54

what is the first step of the cross-bridge cycling to occur?

Answer 54

the myosin head, with an ADP and (P) attached, binds to the myosin binding sites of actin, for a cross bridge and releases the (P) (GRAB)

Question 55

when can a sarcomere generate little or no force?

Answer 55

when it is stretched too much

Question 56

what speeds is calcium diffused out down the steep concentration gradiant and pumped back into the sarcoplasmic retiuclum?

Answer 56

it is released at a quick rate and pumped back in slowly

Question 57

what is occurring during isotonic contractions?

Answer 57

force is generated and muscle length changes

Question 58

what is the action potential caused by?

Answer 58

ions moving through the membrane in ion channels

Question 59

what is the force related to during the muscle twitch?

Answer 59

the amount of calcium

Question 60

what are concentric isotonic contractions?

Answer 60

the muscle shortens

Question 61

when there is an increasing stimulus at a low frequency that occur during stimulus strength and motor unit response that causes a gradual increase in tension above stimulus to a maximal stimulus, what is this due to?

Answer 61

stimulating more motor units (graded response)

Question 62

what needs to be present in order for myosin binding sites to be available?

Answer 62

calcium