Skeletal Muscle

Question 1

How to differentiate muscle

Answer 1

1. structure (skeletal, cardiac, visceral)
2. Histological (striated, smooth)
3. control mode (voluntary, involuntary)

Question 2

only skeletal muscle not attached to bone

Answer 2

tongue

Question 3

more nuclei

Answer 3

skeletal

Question 4

sphincters formed by

Answer 4

smooth muscle

Question 5

surrounding muscle fibers

Answer 5

fascicle

Question 6

muscle fiber=

Answer 6

muscle cell (multineucleated–extend length of muscle)

Question 7

slow fibers

Answer 7

slow cross-bridging/ linking –much myoglobin

Question 8

More mitochondria

Answer 8

slow fibers

Question 9

slow fibers for

Answer 9

postural muscles, endurance, less fatigue (Type I myosin)

Question 10

sarcoplasmic reticulum for

Answer 10

communication throughout muscle–store Ca–> release when activated

Question 11

myofibril

Answer 11

hundreds make up one muscle fiber/ cell–made of stacked sarcomeres

Question 12

A band is

Answer 12

NOT actin–myosin (thick) – (has heads)

Question 13

I band is

Answer 13

ACTIN (thin)

Question 14

where filaments meet

Answer 14

M band (middle of sarcomere) (myosin)

Question 15

Z line – Z line

Answer 15

sarcomere (functional unit of muscle–contraction)

Question 16

myosin protein attaches to the actin at

Answer 16

the heads

Question 17

Ca binds to

Answer 17

G actin binding site

Question 18

I band

Answer 18

thin actin filaments–narrows upon contraction

Question 19

H bands disappears

Answer 19

at full contraction

Question 20

membrane surrounding muscle cells

Answer 20

sarcolemma

Question 21

holding cistern of Ca

Answer 21

terminal cisternae

Question 22

Ca binds to

Answer 22

troponin complex –> tropomyosin changes conformation –> allows myosin heads to attach to actin binding sites

Question 23

mitochondria in

Answer 23

sarcoplasm

Question 24

axon + muscles it innervates

Answer 24

motor unit

Question 25

period when muscle cannot be activated

Answer 25

absolute refractory period

Question 26

when ATP attaches to recently power stroked myosin head

Answer 26

myosin head releases from actin –> ATP is broken down into P and ADP–releasing energy into myosin head –> ready for next power stroke

Question 27

parts of sarcoplasmic reticulum

Answer 27

terminal cisternae at ends of T tubules – hold Ca for release

Question 28

destroy presynaptic motor neuron

Answer 28

flaccid paralysis– polio–>muscle weakness

Question 29

block release of ACh at neuromuscular junction

Answer 29

botulinum toxin–botox

Question 30

Destroy post-synaptic receptors

Answer 30

myasthenia gravis

Question 31

muscle is prevented from shortening when activated–no physical work done despite force development

Answer 31

isometric contraction–i.e. pushing on brick wall

Question 32

Muscle is allowed to shorten while maintaining constant force

Answer 32

isotonic contraction–preceded and followed by isometric contraction

Question 33

Lifting weight

Answer 33

isometric-isotonic-isometric contractions

Question 34

muscle shortening

Answer 34

concentric contraction

Question 35

muscle elongating–muscle contracts with force less than resistance

Answer 35

eccentric contraction

Question 36

contracting =

Answer 36

concentric

Question 37

eccentric =

Answer 37

elongating

Question 38

when not being used Ca goes

Answer 38

back to sarcoplasmic reticulum

Question 39

rigor mortis caused from

Answer 39

no ATP due to dead cells–engaged myosin heads–relaxation from foot upward

Question 40

not enough Ca in blood–less than 50% saturation

Answer 40

no conformational change of tropomyosin–tetany

overactivation of motor nerves–> spasms (tetany)

Question 41

coke/tea urine

Answer 41

rhabdomyolysis–myoglobin in blood–break-down products can damage kidneys

Question 42

increase in muscle cell size–can’t add muscle cells

Answer 42

hypertrophy–myonuclear addition

Question 43

Skeletal muscle tests

Answer 43

1. serum creatine kinase–abnormal if leaks into serum
2. myoglobin–released after muscle injuries-urine tested after injury
3. EMG–measures summation of AP in motor unit–milivolts/ms
4. Biopsy
5. strength and ROM

Question 44

defect in X chromosome leading to absence of dystrophin (anchors cytoskeleton)

Answer 44

Duchaen Muscular Dystrophy–tears muscle cells rather than contracting–tight heal cord (toe walking) WEAK Muscles. Weak hip flexor muscles–leading to “cowboy walk”

Question 45

walking up the legs to rise to standing

Answer 45

Gower’s sign–indicative of lower body weakness

Question 46

Force / velocity relationship

Answer 46

Lighter the force (less force), the faster it will move

Question 47

Tension (skeletal muscle) becomes _______ in cardiac muscle

Answer 47

Stroke volume