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KINE2011: Human Physiology > Module 4: Lecture 1 > Flashcards

Module 4: Lecture 1 Flashcards

1
Q

what controls the force that is generated within the muscle?

A

the action potential in the muscle

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2
Q

what is it called when muscle develops tension and shortens?

A

muscle contraction

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3
Q

what is the largest group of tissues in our body? (50% of our body mass)

A

muscle
- skeletal muscle being 35-40%

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4
Q

what muscle is our voluntary controlled muscle?

A

skeletal muscle
- has motor neurons and it is somatic

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5
Q

which muscle groups are straited?

A

skeletal and cardiac muscle

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6
Q

which muscle groups are involuntary muscles?

A

cardiac and smooth muscle
- our autonomic system

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7
Q

what is another name for a single muscle cell?

A
  • a muscle fibre
  • myofibre
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8
Q

what is a myofibre formed by?

A
  • the fusion of multiple myoblasts
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9
Q

what is a myoblast?

A

an undifferentiated cell that is mononucleated (one single nucleus)

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10
Q

what do myoblasts form into when they fuse?

A

long cylindrical myofibres (which are then multinucleated)
- they are relatively large and elongated

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11
Q

why are myofibres multinucleated?

A

because multiple mononucleated myoblasts are fusing

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12
Q

what is the size of a myofibre in adults?

A

20-100um diameter and up to 20cm long(varies greatly)

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13
Q

what causes striation?

A

alternating band of light and dark bands throughout the muscle fiber
- overlap and relative overlap of the two filaments

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14
Q

what is responsible for the coordinated contraction of the heart muscle?

A

the intercalated discs of cardiac muscle (connection)

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15
Q

what is a whole muscle surrounded by?

A

a layer of dense, irregular connective tissue called the epimysium that is continuous with the tendon sheath

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16
Q

what is continuous with the tendon sheath of a muscle?

A

the epimysium, and the perimysium

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17
Q

what does the perimysium bind?

A

groups of muscle fibres/cells or ‘fascicles’

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18
Q

what does the endomysium bind?

A

individual muscle cells

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19
Q

what are the tiers of a muscle?

A
  • muscle (biggest) (group of fascicles)
  • fascicle (group of cells)
  • muscle fibre (a single cell)
  • myofibril (inside cells)
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20
Q

if we did not have the layers of connective tissue around our muscle tiers, what would happen?

A

all of the forces the muscles generate are not going to be able to be transferred to the tendon and to the joints to produce movement

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21
Q

what is a muscle fiber?

A

a long cylindrical single cell (myofibre) that has myofibrils within it

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22
Q

where do all of the contractile proteins reside?

A

in the myofibRILS

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23
Q

what is the composition of muscle?

A

all of the muscle fibres bound together by layers of connective tissue

24
Q

what is the cell membrane of a myofibre called?

A

sarcolemma

25
Q

where do striations occur within?

A

the myofibRILS
- you have alternating light and dark bands

26
Q

what are the contractile proteins?

A

action (thin filaments)
and
myosin (thick filaments)

27
Q

what takes up majority of skeletal muscle? (80% of the volume of the muscle)

A

myofibrils

28
Q

what is packed between the myofibrils?

A

where other organelles reside

29
Q

what is one unit of the repeating pattern of filaments arranged along the length of the myofibril called?

A

sarcomere - the functional unit of the muscle

30
Q

what is a sarcomere?

A

the smallest unit of a muscle that is able to contract

31
Q

what is responsible for generating force?

A

the thick and thin filaments

32
Q

which band does not allow light to easily pass through it?

A

the Dark A Band

33
Q

which filament and band is located in the center of the sarcomere?

A
  • thick filaments
  • wide dark band = A band
34
Q

how many sets of thin filaments per sarcomere?

A

two sets - one on each end

35
Q

what is a Z line?

A

network of connective tissue proteins, structural proteins that anchors a protein on either side
- the thin dark disc between the two thin filaments

36
Q

what is a sarcomere between?

A

two Z lines

37
Q

what is an I band (Light Band)?

A

where there is thin filaments that are not overlapping with the thick ones

38
Q

what is an H zone?

A

center of the band A where without any thin filament overlapping the thick ones (very narrow)

39
Q

what is an A band (Dark Band)?

A

where your thick and thin filaments overlap

40
Q

what is the M line?

A

centre of the H zone, it is another structural protein that is integral to ensuring that the contraction forces can be transferred to the connective tissue
- holds contractile proteins rigidly so that they can produce the forces and actually transfer them

41
Q

is a thin filament anchored directly to the Z line?

A

yes

42
Q

is a thick filament anchored DIRECTLY to the Z line?

A

no, only at the M line

43
Q

how is the thick filament attached to the Z line?

A

through a protein called titin

44
Q

what is the largest single protein in the body?

A

titin

45
Q

why do filaments need to be anchored into place?

A

to ensure that force can be transferred

46
Q

is titin critical for muscles elasticity?

A

yes

47
Q

what are thick filaments made of?

A

multiple myosin and have both myosin tails and heads

48
Q

what are thin filaments made of?

A

predominantly actin, but also has several regulatory proteins, predominantly troponin and tropomyosin

49
Q

what are key regulators of muscle contraction?

A

tropomyosin and troponin
- they bind to the thin actin filaments

50
Q

how do the thin and thick filaments interact to produce force?

A

from cross bridges
- occurs because the myosin head has a binding site that can attach to actin so when we remove the blocking mechanism from troponin and tropomyosin, it allows actin and myosin to connect and attached with with one another.
- myosin molecule extends towards the actin filament and it connects and forms the molecular connection that we refer to as a cross bridge

51
Q

what is the sliding movement of thick and thin filaments?

A

thin filaments move toward the center (M-line) of the sarcomere due to the myosin head pulling it with a power stroke which causes the muscle to shorten

52
Q

what is going to surround any given thick filament?

A

six thin filaments in a hexagonal pattern
- so there is going to be myosin heads facing each of these filaments so it can interact in three dimensional structure

53
Q

what direction does the myosin heads face?

A

all six directions towards the action so it can interact in three dimensional structure

54
Q

what surrounds any given thin filament?

A

three myosin filaments that can then interact with it by producing the myosin heads in that orientation

55
Q

how many actin can each myosin interact with?

A

6 actin filaments

56
Q

how many myosin can each actin interact with?

A

3 myosin filaments

KINE2011: Human Physiology (29 decks)

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