Muscle Physiology Flashcards Preview

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Flashcards in Muscle Physiology Deck (39):
1

isotonic

muscle contractions with movement
-goes up and comes straight down on graph

2

what determines time of twitch?

time that calcium is present in the cytosol
time for detachment of myosin from actin so cycle can repeat

3

heavy load

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

4

when is tension created in a muscle?

when the myosin head is attached to the actin

5

what happens in an eccentric contraction?

tension is present, but muscle lengthening is happening

6

when will isometric turn into eccentric?

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

7

what are factors that influence muscle movement?

how fast ATP is able to hydrolyze

8

frequency-tension relationship

twitch lasts longer than AP (action potential)
-not having to do with intensity

9

summation

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

10

tetanus

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

11

unfused tetanus

low stimulus frequency (low firing rate)
-fatigue will set in layer so many muscles use this

12

fused tetanus

high stimulus frequency (high firing rate)
-3-5 times more tension than isometric twitch

13

length-tension relationship

ideal length at which muscle can generate the most tension

14

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

relaxed muscle length

15

what does titin attach to?

thick filament

16

what does titin do?

passive elastin tension of muscle

17

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

creatine phosphate
oxidative phosphorylation in mitochondria
glycolytic pathway

18

creatine phosphate

protein in muscle fiber, gives up a phosphorus to make ATP
made in liver, kidney and pancreas

19

creatine kinase

enzyme used to phosphorylate ADP using creatine phosphate

20

cardiac enzymes

CK and troponin
(elevated numbers indicates MI)

21

creatine

well controlled studies indicate that it is useful for muscle health

22

what are the characteristics of muscle fatigue?

decreased shortened velocity
slower rate of relaxation

23

high-frequency fatigue

muscles fatigue rapidly, but recover rapidly

24

low-frequency fatigue

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

25

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

a protective mechanism

26

what happens during fatigue in short term?

conduction failure
lactic acid buildup
inhibition of cross-bridge cycling

27

conduction failure

muscle AP don't get down into T-Tubule
results from buildup of potassium in the T-tubules during repolarization

28

lactic acid buildup

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

29

inhibition of cross-bridge cycling

delays detachment of myosin from actin
impaired relaxation

30

long duration exercise

depletion of substrates is probably the most important

31

fast fibers (type II)

high ATPase activity on myosin
rate of cross bridge is 4x faster

32

slow fibers (type I)

lower ATPase activity on myosin
slower contraction
-stability muscles

33

oxidative fibers (red fibers)

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

34

glycolytic fibers (white fibers)

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

35

what are the three types of muscle fibers?

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

36

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

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

37

what is the sequence response of motor units?

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

38

fine movement will have what kind of motor unit?

1 motor neuron and 13 muscle fibers

39

gross movement will have what kind of motor unit?

1 motor neuron to 1000 muscle fibers

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