Exam 3 (chapter 12 part 3)

Question 1

more muscle fibers contracting = ____________ force

Answer 1

more

Question 2

stimulating more muscle fibers to contract

Answer 2

recruitment

Question 3

bundle of muscle fibers

Answer 3

muscle

Question 4

more muscle fibers contracting = _____________ overall muscle ____

Answer 4

greater

tension

Question 5

recruitment occurs at the level of the ___________ ____________

Answer 5

motor unit

Question 6

activation of the motor neuron activates _________ muscle fibers in the motor unit

Answer 6

all

Question 7

increases in tension occur in steps _______________ to the size of the motor unit

Answer 7

proportional

Question 8

muscles for delicate movements

Answer 8

small motor units (often inervate type 1)

Question 9

muscles for stregth

Answer 9

large motor units

Question 10

fiber diameter for weaker movements

Answer 10

lower

Question 11

fiber diameter for stronger movements

Answer 11

higher

Question 12

• small fibers
• small motor neuron cell bodies
• small axon diameters

Answer 12

small motor units

Question 13

• large fibers
• large motor neuron cell bodies
• large axon diameters

Answer 13

large motor units

Question 14

order of motor unit recruitment is related to size of motor units

• small units recruited first
• large units recruited second

Answer 14

ye

Question 15

small motor units are recruited _____________ while large motor units are recruited ______________

Answer 15

first

last

Question 16

are larger neurons more or less difficult to depolarize to threshold?

Answer 16

more (requires greater synaptic input)

Question 17

how muscle cells generate ATP

Answer 17

muscle metabolism

Question 18

___________ is required by muscle to generate work (contraction)
- drive cross bridge cycling

Answer 18

ATP

Question 19

what drives cross bridge cycling?

Answer 19

ATP

Question 20

what are a muscle cells 3 sources of ATP?

Answer 20

phosphorylation of ADP by creatine phosphate (shortest), oxidative phosphorylation of ADP (in mitochondria), anaerobic glycolysis

Question 21

what is the role of creatinine/creatine phosphate system?

Answer 21

small store of ATP at rest (must quickly increase ATP synthesis) roughly 12 seconds

Question 22

• use of ATP drives reaction to the right (need to make more)
• can only supply up to 5x the quantity of ATP

Answer 22

law of mass action

Question 23

during light to moderate exercise, what supplies glucose initially?

Answer 23

glycogen (carb stores)

Question 24

after 30 min of light to moderate exercise, what is in the blood?

Answer 24

glucose, fatty acids (broken down for energy)

Question 25

when O2 is needed during light to moderate exercise, ventilation _____________, heart rate and contraction _____________, and vessels to muscle __________________,

Answer 25

increases, increases, dilates

Question 26

during light to moderate exercise there is a transient _____________ in GLUT4

Answer 26

increase

Question 27

during heavy exercise, what supplies ATP?

Answer 27

anaerobic glycolysis (lactate)

Question 28

what is the rate limiting step of the cycle?

Answer 28

ATP hydrolysis

Question 29

higher rate of ATP hydrolysis = _______________ cross bridge cycling

Answer 29

faster

Question 30

myosin with fast ATPase activity - contract 2-3 times more rapidly - relax more rapidly

Answer 30

fast fibers (2a, 2x)

Question 31

myosin with slow ATPase activity | - last 10x longer

Answer 31

Slow fibers (1)

Question 32

- anaerobic glycolysis - fewer mitochondria - many glycolytic enzymes - high glycogen stores - use little oxygen - large diameter - quick to fatigue

Answer 32

glycolytic fibers

Question 33

- oxidative phosphorylation - many mitochondria - myoglobin (red) - small diameter - resistant to fatigue - many capillaries

Answer 33

oxidative fibers

Question 34

what are the 3 skeletal muscle fiber types?

Answer 34

1 (slow oxidative), 2a (fast oxidative), 2x (fast glycolytic)

Question 35

- low myosin ATPase - high oxidative capacity (aerobic) - small diameter - fatigue slowly (endurance)

Answer 35

slow oxidative fibers (type 1)

Question 36

- high myosin ATPase activity - high glycolytic capacity - no myoglobin - large diameter - fatigue rapidly

Answer 36

fast glycolytic fibers (2x)

Question 37

- intermediate myosin ATPase activity - high oxidative capacity - myoglobin - slow to fatigue, but more rapid than slow oxidative fibers - intermediate diameter

Answer 37

fast oxidative fibers (2a)

Question 38

An oxygen-storing, pigmented protein in muscle cells. | - consists of a backbone and heme-binding domain

Answer 38

myoglobin

Question 39

slow oxidative (red, type 1): - oxidative capacity? - glycolytic capacity? - speed of contraction? - myosin ATPase activity? - mitochondrial density? - capillary density? - myoglobin content? - resistance to fatigue? - fiber diameter? - motor unit size? - force generating capacity?

Answer 39

slow oxidative (red, type 1): - oxidative capacity: high - glycolytic capacity: low - speed of contraction: slow - myosin ATPase activity: low - mitochondrial density: high - capillary density:high - myoglobin content: high - resistance to fatigue: high - fiber diameter: small - motor unit size: small - force generating capacity: low

Question 40

Fast oxidative (pink, type 2a): - oxidative capacity? - glycolytic capacity? - speed of contraction? - myosin ATPase activity? - mitochondrial density? - capillary density? - myoglobin content? - resistance to fatigue? - fiber diameter? - motor unit size? - force generating capacity?

Answer 40

Fast oxidative (red): - oxidative capacity: high - glycolytic capacity: intermediate - speed of contraction: intermediate - myosin ATPase activity:intermediate - mitochondrial density: high - capillary density: high - myoglobin contenthigh - resistance to fatigue: intermediate - fiber diameter: intermediate - motor unit size: intermediate - force generating capacity: intermediate

Question 41

Fast glycolytic (white): - oxidative capacity? - glycolytic capacity? - speed of contraction? - myosin ATPase activity? - mitochondrial density? - capillary density? - myoglobin content? - resistance to fatigue? - fiber diameter? - motor unit size? - force generating capacity?

Answer 41

Fast glycolytic (white): - oxidative capacity: low - glycolytic capacity: high - speed of contraction: fast - myosin ATPase activity: high - mitochondrial density: low - capillary density: low - myoglobin content: low - resistance to fatigue: low - fiber diameter: large - motor unit size: large - force generating capacity: high

Question 42

each muscle is a ____________ of fiber types

Answer 42

mixture

Question 43

in a single motor unit, do all muscle fibers have to be of the same type?

Answer 43

yes

Question 44

can you change myosin ATPase activity?

Answer 44

no (born with)

Question 45

what does oxidative capacity mean?

Answer 45

oxidative phosphorylation

Question 46

speed of contraction depends on what?

Answer 46

ATP hydrolysis (ATPase activity)

Question 47

can you change capillary density?

Answer 47

yes

Question 48

can you change myoglobin content?

Answer 48

yes

Question 49

can you change resistance to fatigue?

Answer 49

yes

Question 50

can you change fiber diameter?

Answer 50

yes

Question 51

can you change force generating capacity?

Answer 51

yes

Question 52

large diameter = ____________ sarcomeres in parallel

Answer 52

more

Question 53

can you change muscle fiberr number

Answer 53

no

Question 54

does having a small or large diameter make O2 delivery more efficient?

Answer 54

small (type 1 prevalence)

Question 55

what is recruitment order of the skeletal muscle fiber types?

Answer 55

1 (slow oxidative), 2a (fast oxidative), 2x (fast glyoclytic)

Question 56

what is an example of a time when fast glycolytic fibers are being used?

Answer 56

sprinting

Question 57

what is an example of a time when slow oxidative fibers are being used?

Answer 57

long distance running