Muscle Physiology

Question 1

isotonic

Answer 1

muscle contractions with movement

-goes up and comes straight down on graph

Question 2

what determines time of twitch?

Answer 2

time that calcium is present in the cytosol

time for detachment of myosin from actin so cycle can repeat

Question 3

heavy load

Answer 3

longer latent period
lower velocity of shortening
distance shortened is less
duration of twitch is shorter

Question 4

when is tension created in a muscle?

Answer 4

when the myosin head is attached to the actin

Question 5

what happens in an eccentric contraction?

Answer 5

tension is present, but muscle lengthening is happening

Question 6

when will isometric turn into eccentric?

Answer 6

when load exceed’s muscle’s ability to cause movement

Question 7

what are factors that influence muscle movement?

Answer 7

how fast ATP is able to hydrolyze

Question 8

frequency-tension relationship

Answer 8

twitch lasts longer than AP (action potential)

-not having to do with intensity

Question 9

summation

Answer 9

keep adding (stimulating) the muscle, causes Ca flooding and maintains muscle contraction

Question 10

tetanus

Answer 10

normal muscle physiology, a maintained contraction in response to repetitive APs

Question 11

unfused tetanus

Answer 11

low stimulus frequency (low firing rate)

-fatigue will set in layer so many muscles use this

Question 12

fused tetanus

Answer 12

high stimulus frequency (high firing rate)

-3-5 times more tension than isometric twitch

Question 13

length-tension relationship

Answer 13

ideal length at which muscle can generate the most tension

Question 14

in resting state of muscle, the optimal length is the same as the

Answer 14

relaxed muscle length

Question 15

what does titin attach to?

Answer 15

thick filament

Question 16

what does titin do?

Answer 16

passive elastin tension of muscle

Question 17

what are the 3 ways that ATP is produced for muscles?

Answer 17

creatine phosphate
oxidative phosphorylation in mitochondria
glycolytic pathway

Question 18

creatine phosphate

Answer 18

protein in muscle fiber, gives up a phosphorus to make ATP

made in liver, kidney and pancreas

Question 19

creatine kinase

Answer 19

enzyme used to phosphorylate ADP using creatine phosphate

Question 20

cardiac enzymes

Answer 20

CK and troponin

elevated numbers indicates MI

Question 21

creatine

Answer 21

well controlled studies indicate that it is useful for muscle health

Question 22

what are the characteristics of muscle fatigue?

Answer 22

decreased shortened velocity

slower rate of relaxation

Question 23

high-frequency fatigue

Answer 23

muscles fatigue rapidly, but recover rapidly

Question 24

low-frequency fatigue

Answer 24

develops more slowly with low intensity, long duration, requires longer to recover

Question 25

what do people thing fatigue is for (long term)?

Answer 25

a protective mechanism

Question 26

what happens during fatigue in short term?

Answer 26

conduction failure
lactic acid buildup
inhibition of cross-bridge cycling

Question 27

conduction failure

Answer 27

muscle AP don’t get down into T-Tubule

results from buildup of potassium in the T-tubules during repolarization

Question 28

lactic acid buildup

Answer 28

elevated H+ buildup which alters muscle proteins and affects calcium ATPase pump

Question 29

inhibition of cross-bridge cycling

Answer 29

delays detachment of myosin from actin

impaired relaxation

Question 30

long duration exercise

Answer 30

depletion of substrates is probably the most important

Question 31

fast fibers (type II)

Answer 31

high ATPase activity on myosin

rate of cross bridge is 4x faster

Question 32

slow fibers (type I)

Answer 32

lower ATPase activity on myosin
slower contraction
-stability muscles

Question 33

oxidative fibers (red fibers)

Answer 33

oxidative phosphorylation
many mitochondria
many blood vessels
high concentration of myoglobin
smaller diameter

Question 34

glycolytic fibers (white fibers)

Answer 34

few mitochondria
high concentration of glycolytic enzymes
few blood vessels
little myoglobin
larger diameter
fatigue rapidly

Question 35

what are the three types of muscle fibers?

Answer 35

slow-oxidative (resistant to fatigue)
fast-oxidation or fast oxidative-glycolytic
fast-glycolytic (fatigue rapidly)

Question 36

how many different types of muscle fiber are contained in one motor unit?

Answer 36

1 (all the same type of fiber, but have multiple motor units)

Question 37

what is the sequence response of motor units?

Answer 37

1. slow-ox
2. fast-ox
3. fast-glyc
   (calling one each one makes the response more forceful)

Question 38

fine movement will have what kind of motor unit?

Answer 38

1 motor neuron and 13 muscle fibers

Question 39

gross movement will have what kind of motor unit?

Answer 39

1 motor neuron to 1000 muscle fibers