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General Veterinary Physiology > Chapter 6: Contraction of Skeletal Muscle > Flashcards

Chapter 6: Contraction of Skeletal Muscle Flashcards

1
Q

how many percent of the body is skeletal muscle

A

40%

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2
Q

how many percent is smooth
and cardiac muscle in the body?

A

10%

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3
Q

The sarcolemma consists of a true cell membrane, called
the?

A

plasma membrane

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4
Q

outer coat made
up of a thin layer of polysaccharidematerial that
contains numerous thin collagen fibrils

A

plasma membrane

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5
Q

turn collect into bundles to form the muscle tendons thatthen insert into the bones.

A

tendon fibers

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6
Q

Each muscle fiber contains
several hundredto several thousand

A

myofibrils

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7
Q

Each myofibril is composed
of about?

A

1500 myosin filaments and 3000 actin filaments

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8
Q

The light
bands contain only actin filaments and are called?

A

I bands

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9
Q

dark bands contain

A

myosin filaments

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10
Q

ends of the actin filaments where they
overlap the myosin, and are called?

A

A bands

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11
Q

the small projections from the sides of the
myosin filaments

A

cross-bridges

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12
Q

ends of the
actin filaments are attached to a so-called?

A

Z-discs

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13
Q

composed of
filamentous proteins different from the actin and
myosin filaments

A

Z disc

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14
Q

The portion of the myofibril (or of the whole
muscle fiber) that lies between two successive Z
discs is called a?

A

sarcomere

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15
Q

at
this length the muscle is capable of generating its greatest force of contraction called

A

sarcoplasm

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16
Q

sarcoplasm surrounding the myofibrils
of each muscle fiber is an extensive reticulum called the ?

A

sarcoplasmic reticulum

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17
Q

This
reticulum has a special organization that is extremely important in controlling muscle contraction

A

sarcoplasmic reticulum

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18
Q

achieved by a large number of filamentous molecules
of a protein called?

A

titin

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19
Q

acts on a local area of the
musclefiber membrane to open multiple
“acetylcholine-gated
”cation channels through
protein molecules floating inthe membrane

A

acetylcholine

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20
Q

initiate attractive forces
between the actin and myosin filaments, causing them to slide along side each other, which is
the contractile process

A

calcium ions

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21
Q

the Z discs have been
pulled bythe actin filaments up to the ends of
the myosin filaments. Thus, muscle contraction
occurs by a

A

sliding filament mechanism

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22
Q

what causes the actin filaments to slide
inward among the myosin filaments?

A

caused by forces generated by interaction of the
cross-bridges from the myosin filaments with the
actin filaments.

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23
Q

The backbone of
the actin filament is a double-stranded

A

F-actin protein molecule

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24
Q

Each strand of the double F-actin helix is
composed of polymerized

A

G actin molecules

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25
Q

the active sites on the actinfilaments
with which the cross-bridges of the myosin filaments interact to cause muscle contraction

A

ADP molecules

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26
Q

Attached to one end of each tropomyosin
molecule is a

A

troponin

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27
Q

The actin filament also contains another protein

A

tropomyosin

28
Q

Attached intermittently along the sides of the
tropomyosin molecules are still other protein
molecules called

A

troponin

29
Q

has a strong affinity for actin

A

troponin I

30
Q

subunits for tropomyosin

A

troponin T

31
Q

subunits for tropomyosin

A

troponin T

32
Q

subunits for calcium ions

A

troponin C

33
Q

The new alignment of forces causes the
head to tilt toward thearm and to drag the actin
filament along with it

A

power stroke

34
Q

the greater the amount of work performed by the muscle, the greater the amount of ATP that is cleaved

A

fenn effect

35
Q

the increase in tension that occurs during contraction

A

active tension

36
Q

contracts rapidly when it contracts against no load—to a state of full contraction in
about 0.1 second for the average muscle

A

skeletal muscle

37
Q

When a muscle contracts against a load, it performs

A

work

38
Q

The second important source of energy, which
is used to reconstitute both ATP and phosphocreatine

A

glycolysis

39
Q

third and final source of energy. means combining
oxygen with theend products of glycolysis and
with various other cellular foodstuffs to liberate
ATP

A

oxidative metabolism

40
Q

3 sources of energy for muscle contractions

A
  1. phosphocreatine
  2. glycolysis
  3. oxidative metabolism
41
Q

what do you call of muscle contraction when the muscle does not
shorten during contraction

A

isometric

42
Q

when it does
shorten but thetension on the muscle remains constant
throughout the contraction

A

isotonic

43
Q

Muscles that react rapidly,
including anterior tibialis

A

fast muscle fibers

44
Q

muscles such as soleus that respond slowly but
with prolonged contraction

A

slow fibers

45
Q

Slow Fibers (Type 1, Red Muscle)

A

(1) Smaller fibers
(2)Also innervated by smaller nerve fibers
(3) More
extensive blood vessel system and capillaries to supply
extra amount of oxygen
(4) Greatly increased numbers of mitochondria,also to support high levels of oxidative metabolism
(5) Fiber Contain large amounts of
myoglobin, an iron-containing protein similar to hemoglobin in red blood cells

46
Q

The
myoglobin gives the slow muscle a reddish appearance
andthe name?

A

red muscle

47
Q

Fast Fibers (Type II, White Muscle)

A

(1) Large fibers
for great strength of contraction
(2) Extensive sarcoplasmic reticulum for rapid release of calcium ions to
initiate contraction
(3) Large amounts of glycolytic
enzymes for rapid release of energy by the glycolytic
process
(4) Less extensive blood supply because oxidative metabolism is of secondary importance
(5) Fewer
mitochondria, also because oxidative metabolism is
secondary

48
Q

A deficit of red myoglobin in fast muscle
gives it the name

A

white muscle

49
Q

All the
muscle fibers innervated bya single nerve fiber are called a

A

motor unit

50
Q

means the adding together
of individual twitch contractions to increase the
intensity ofoverall muscle contraction

A

summation

51
Q

Summation occurs in two ways;

A

✓ multiple fiber summation
✓ frequency summation

52
Q

increasing the number
of motor units contracting simultaneously

A

multiple fiber summation

53
Q

increasing the frequency of contraction

A

frequency summation

54
Q

frequency summation can lead to?

A

tetanization

55
Q

When the frequency reaches acritical level, the successive contractions eventually become
so rapid that they fuse together and the whole muscle
contraction appears to be completely smooth and continuous

A

tetanization

56
Q

the strength of contractionincreases to a plateau, a phenomenon called the?

A

staircase effect or treppe

57
Q

Even when muscles are at
rest, a certain amount of tautness usually remains.
This is called?

A

muscle tone

58
Q

study of different types of
muscles, lever systems, and their movements is called?

A

kinesiology

59
Q

total mass of a muscle increases

A

muscle hypertrophy

60
Q

total mass of a muscle decrease

A

muscle atrophy

61
Q

causing enlargement of
the individual muscle fibers

A

simple fiber hypertrophy

62
Q

occurs to a much
greater extent when themuscle is loaded during the
contractile process

A

hypertrophy

63
Q

The pathway that appears to account
for much of the protein degradation in a muscle undergoing atrophy is the

A

ATP dependent ubiquitin-
proteasome pathway

64
Q

increase in fiber number

A

fiber hyperplasia

65
Q

fibrous tissue that replaces the muscle fibers during denervation atrophy also has a tendency to continueshortening for many months, which is called

A

contracture

66
Q

causes large
motor units

A

macromotor units

67
Q

muscles of the body go
into a state of contracture called? that is,
the muscles contract and become rigid

A

rigor mortis

General Veterinary Physiology (9 decks)

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