Skeletal Muscle Contraction

Question 1

epimysium

Answer 1

CT around entire muscle

Question 2

Muscle

Answer 2

formed by multiple fascicles

Question 3

perimysium

Answer 3

CT around each fascicle

Question 4

fascicle

Answer 4

bundle of myofiber

Question 5

endomysium

Answer 5

CT around each myofiber

Question 6

sarcolemma

Answer 6

muscle fiber cell membrane = plasmalemma

Question 7

myofiber

Answer 7

individual multinucleated muscle cell

Question 8

myofibril

Answer 8

chain of sarcomeres in a myofiber

Question 9

myofilament

Answer 9

actin/myosin filaments that make sarcomere

Question 10

Z lines

Answer 10

anchor actin, at each end of sarcomere

Question 11

I bands

Answer 11

solely actin, width changes on contraction

Question 12

A bands

Answer 12

actin and myosin. No width change

Question 13

H bands

Answer 13

solely myosin. width changes on contraction

Question 14

Sliding Filament Mechanism Events

Answer 14

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.

Question 15

Dihydropyridine Receptors

Answer 15

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

Question 16

Ryanodine Receptors

Answer 16

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]

Question 17

Where is ATP required for muscle contraction?

Answer 17

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

Question 18

[ATP] in muscle fiber??

Answer 18

4mmol, contracts for 1-2 seconds

Question 19

Phosphocreatine

Answer 19

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

Question 20

Glycolysis

Answer 20

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

Question 21

How much energy is provided by Oxidative Metabolism?

Answer 21

95% for long term contractions.

Question 22

Isometric Muscle Contraction

Answer 22

increase in tension but not length.

Question 23

Isotonic muscle contraction

Answer 23

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

Question 24

Fast-twitch fibers

Answer 24

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

Question 25

Slow-twitch fibers

Answer 25

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

Question 26

How do muscles increase in size?

Answer 26

increase the mass of myofiber and muscle

Question 27

Summation

Answer 27

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.

Question 28

Tetany

Answer 28

high frequency causing muscle to stay contracted

Question 29

A lever is?

Answer 29

rigid bone rotating around pivot point

Question 30

In-lever arm

Answer 30

distance from in-force to fulcrum

Question 31

out-lever arm

Answer 31

distance from the out-force to fulcrum

Question 32

First class lever system

Answer 32

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

Question 33

Second class lever system

Answer 33

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

Question 34

Third class lever system

Answer 34

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