Motor Unit and acute modulation

Question 1

what is key for muscle contraction?

Answer 1

Calcium ions “on and off switch”

Question 2

when the muscle is resting or relaxed, myosin is attached to

Answer 2

actin in a “weak binding state”

Question 3

where is calcium stored?

Answer 3

Sarcoplasmic reticulum

Question 4

action potential is generated in a

Answer 4

motor nerve

Question 5

(muscle turning on) Acetylcholine opens what gate?

Answer 5

chemical gated Na+ channel

Question 6

(muscle turning on) T-tubules spread impulses along the?

Answer 6

triads

Question 7

triads?

Answer 7

the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side.

Question 8

(muscle turning on) Depolarazation causes calcium gates to?

Answer 8

to open in the sarcoplasmic reticulum

Question 9

(muscle turning on)calcium empties out of the

Answer 9

Sarcoplasmic reticulum into the cytoplasm and binds Tn-C

Question 10

(muscle turning on)Once calcium is bound to the Tn-C, what occurs?

Answer 10

myosin can attach in the strong binding state

Question 11

Muscle contraction is turned off by

Answer 11

removing calcium

Question 12

(muscle turning off) calcium is pumped out of the cytoplasm into

Answer 12

the sarcoplasmic reticulum via Calcium-pumps

Question 13

(muscle turning off) calcium pumps require energy in form of

Answer 13

ATP

to respond immediately to calcium

Question 14

(muscle turning off) The rate and amount of calcium removal is tied to

Answer 14

the number of calcium pumps

Question 15

(muscle turning off) when calcium is pumped out what occurs?

Answer 15

myosin goes back into the weak binding state and the muscle becomes relaxed

Question 16

After the myosin goes back into the weak binding state, the muscle is also

Answer 16

repolarizing and can not turn on again unti its repolarized

Question 17

myosin immediately hydrolyzes the ATP into

Answer 17

ADP+Pi

Question 18

Calcium binding to TnC starts a

Answer 18

shape change and allows myosin to bind action in the strong binding state

Question 19

once in a strong binding state myosin can?

Answer 19

exert force upon the actin

Question 20

in a strong binding state, force occurs when the cross bridge?

Answer 20

changes from a 90 to 45 orientation

Question 21

The 90 to 45 occur when

Answer 21

the Pi is released from the myosin. if its not released no force is produced

Question 22

After the Pi is released, the cross bridge cycle will not continue until

Answer 22

the actin and myosin bond is broken

Question 23

The actin and myosin bond is broken by

Answer 23

ATP attachment

Question 24

Before the ATP can break the actin-myosin bond

Answer 24

ADP must be released from the myosin. The cycle is in a holding pattern until its released.

Question 25

If ADP is released but there is no ATP available, the cycle enters a ?

Answer 25

state of rigor

Question 26

rigor?

Answer 26

the actin-myosin are strongly stuck to each other (stiffness)

Question 27

Once ADP is released?

Answer 27

ATP binds myosin, breaks the actin-myosin bond and the whole cycle starts again. As long as there is neural stimulation

Question 28

muscle action is intiated by

Answer 28

nerve impulse

Question 29

The nerve releases ACH, which allows

Answer 29

sodium to enter and depolarize the cell

Question 30

If the cell is sufficiently depolarized,

Answer 30

an action potential occurs which releases stored calcium ions

Question 31

Calcium ions intiate a series of events leading to

Answer 31

muscle cell contraction (Z line move towads each other)

Question 32

Once myosin binds to actin,

Answer 32

the myosin head tilts and pulls the actin filament so they slide across each other

Question 33

Muscle action end when

Answer 33

calcium is pumped out of the sarcoplasm to the sarcoplasmic reticulum for storage

Question 34

Energy for muscle acton is provided when the myosin head binds to

Answer 34

ATP

Question 35

ATPase on the myosin head splits the?

Answer 35

ATP into a usable energy source

Question 36

Biochemical properties of muscle fiber types

Answer 36

• oxidative capacity

- type of ATPase and myosin heavy chain

Question 37

Contractile properties of muscle fiber types

Answer 37

• maximal force production
• speed of contraction (Vmax)
• muscle fiber efficiency

Question 38

Slow twitch fibers properties

Answer 38

• high aerobic (oxidative) capacity and fatigue resistance
• Low anaerobic (glycolytic) capacity and motor unit strength
• slow contractile speed

Question 39

Fast twitch type IIa properties

Answer 39

• moderate/high aerobic (oxidative) capacity and fatigue resistance
• High anaerobic (glycolytic) capacity and motor unit strength
• fast contractile speed

Question 40

Fast twitch type IIx

Answer 40

• Low aerobic (oxidative) capacity and fatigue resistance

- high anaerobic (glycolytic) capacity and motor unit strength

Question 41

All or none response

Answer 41

for a motor unit to be recruited into activity the motor nerve impulse must meet or exceed the threshold

Question 42

hypertrophy

Answer 42

increase of muscle size

Question 43

hyperplasia

Answer 43

increase of muscle cell number

Question 44

equation of power

Answer 44

power=force x velocity

Question 45

force is determined by

Answer 45

Pi release

Question 46

Velocity is determined by

Answer 46

ADP release

Question 47

more sarcomeres in parallel

Answer 47

favor force production

Question 48

more sarcomeres in series

Answer 48

favor velocity

Question 49

force magnitude is equal to

Answer 49

the number of attached cross bridges going from 90 to 45

Question 50

contraction velocity is related to

Answer 50

the cross bridge cycling rate or the rate of ADP release strongly related to the myosin ATPase type

Question 51

2 people can generate the same power by different means. Power production can be changed by

Answer 51

changing force, velocity or both

Question 52

both hypertrophy and hyperplasia are controlled by

Answer 52

satellite cells