Skeletal Muscle Contraction Flashcards Preview

Zach's Physiology Card > Skeletal Muscle Contraction > Flashcards

Flashcards in Skeletal Muscle Contraction Deck (34):
1

epimysium

CT around entire muscle

2

Muscle

formed by multiple fascicles

3

perimysium

CT around each fascicle

4

fascicle

bundle of myofiber

5

endomysium

CT around each myofiber

6

sarcolemma

muscle fiber cell membrane = plasmalemma

7

myofiber

individual multinucleated muscle cell

8

myofibril

chain of sarcomeres in a myofiber

9

myofilament

actin/myosin filaments that make sarcomere

10

Z lines

anchor actin, at each end of sarcomere

11

I bands

solely actin, width changes on contraction

12

A bands

actin and myosin. No width change

13

H bands

solely myosin. width changes on contraction

14

Sliding Filament Mechanism Events

1. action potential arrives at terminal end of nerve. 2. Ca channel opens. 3) release of Ach from synaptic vesicles to cleft. 4) sarcolemma Na channels open. 5) action potential generated on sarcolemma/ 6)raynodine receptor on SR interact with VGC on T tubules. 7)ryanodine-sensitive Ca release channels open. 8) cytosol increases Ca ion. 9) sliding filament mechanism is activated.10) Ca ion bind with troponin. 11) tropomysin opens actin binding site. 12)ATPase heads of myosin, split ATP to bind actin. 13)deformation of myosin heads allows thick/thin sliding. 14)2nd ATP binds myosin->releasing actin. 15) repeating process. 16) contraction stops Ca pumps move Ca ions back to SR.

15

Dihydropyridine Receptors

1)quadruplet L-type Ca channels. 2) located @sarcoleme T-tubules. 3) cause conformation change in ryanodine receptors. 4)Ca flows to cytosol in channel

16

Ryanodine Receptors

1) located on cisternae of SR. 2)open bc of change in DHP. 3) Ca allowed into cytosol from SR. 4) Calsequestrin maintains optimum [Ca]

17

Where is ATP required for muscle contraction?

1)sliding filament mechanism. 2)pumps Ca from sarcoplasm to SR. 3)Na-K pump to establish the RP(-90)

18

[ATP] in muscle fiber??

4mmol, contracts for 1-2 seconds

19

Phosphocreatine

1)rapid energy release 2) reconstitutes ATP 3) combination provides 5-8 second contraction.

20

Glycolysis

causes lactic acid build up, only good for 1 second.

21

How much energy is provided by Oxidative Metabolism?

95% for long term contractions.

22

Isometric Muscle Contraction

increase in tension but not length.

23

Isotonic muscle contraction

Eccentric: lengthening of muscle.
Concentric: shortening of muscle.

24

Fast-twitch fibers

1)fewer mitochondria 2) anaerobic respiration->build up of pyruvic acid. 3) little myoglobin. 4) large [ATPase] 5) aka 'white'

25

Slow-twitch fibers

1) more mitochondria 2) aerobic respiration 3) more myoglobin 4) small [ATPase]

26

How do muscles increase in size?

increase the mass of myofiber and muscle

27

Summation

electrical events occur faster than mechanical. 2)extra spike occur before previous Ca ion return to SR. 3)Increases Ca ion in cytosol and increases rate of cycling between myosin and actin. Increasing muscle tension.

28

Tetany

high frequency causing muscle to stay contracted

29

A lever is?

rigid bone rotating around pivot point

30

In-lever arm

distance from in-force to fulcrum

31

out-lever arm

distance from the out-force to fulcrum

32

First class lever system

1) fulcrum is in the middle. 2) raising chin using sternoclediomastoids. (atlas-axis=fulcrum) 3) in-force& out-force move oppositely

33

Second class lever system

Both in/out forces are in same direction. (resistance is in middle)
raise body on ball of feet. fulcrum= ball of foot

34

Third class lever system

both in/out forces on same side of fulcrum. effort is in middle. Lift wt in palm of hand.