muscle Flashcards

1
Q

skeletal muscle structure

A

multinucleated

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2
Q

cardiac muscle structure

A

single nucleus
intercalating disks

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3
Q

smooth muscle structure

A

mononucleated

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4
Q

what does skeletal muscle form from in utero

A

mononucleated myoblasts

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5
Q

can myoblasts self repilcate

A

no- can’t replace if damaged
hence scar tissue

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6
Q

what attaches muscle to bones

A

tendons

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7
Q

when injured what can skeletal muscle cells do

A

replaced by satellite cells

undergo hypertrophy to copensate

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8
Q

1 skeletal muscle fibre is made of lots of

A

myofibrils

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9
Q

what are myofibrils made from

A

sarcomeres- the repeating unit

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10
Q

thick filaments are made from ____ and contain

A

myosin

cross bridges

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11
Q

thin filaments are made from

A

actin

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12
Q

what causes cross bridge to attach to actin

A

hydrolysis of ATP- ATP gets converted to ADP

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13
Q

what causes the cross bridge to detach from actin

A

attachment of ATP

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14
Q

role of troponin, tropomyosin and Ca2+

A

tropomyosin covers myosin binding site, helped by troponin

Ca2+ stops this by binding to troponin making it pull tropomyosin away

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15
Q

what does the sarcoplasmic reticulum store

A

Ca2+ ions

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16
Q

what do the transverse tubules act as

A

conduction system- AcH travels down it to reach the sarcoplasmic reticulum

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17
Q

muscle units consist of

A

motor neurons and muscle fibres

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18
Q

force exerted by muscle

A

tension

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19
Q

force exerted on muscle

A

load

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20
Q

contraction with constant length

A

isometric- holding still

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21
Q

contraction with shortening length

A

isotonic- running

22
Q

a single action potential to a muscle fibre is called

A

a twitch

23
Q

contraction time depends on

A

Ca2+

24
Q

whats tetanus

A

multiple twitch added together- summation

25
Q

tetanic tension vs twitch tension

A

tetanic is greater- Ca2+ never gets low so no re blocking

26
Q

optimal length l0 is

A

the muscle length that gets the greatest isometric tension

27
Q

second way ATP is used in muscles

A

ends contractions by pumping Ca2+ back into sarcoplasmic reticulum

28
Q

what does fatigue prevent

A

fatigue- prevents using up all ATP leaving myosin stuck bound to actin

29
Q

what causes fatigue in short, high intensity exercise

A
  • increased K+
  • increased lactic acid
  • increased ADP inhibits cycle
30
Q

what causes fatigue in long, low intensity exercise

A
  • decreased muscle glycogen
  • decreased blood glucose
  • dehydration
  • central command fatigue- no “will to win”
31
Q

fast vs slow muscle fibre types

A

fast- myosin has high ATPase

slow- myosin has low ATPase

32
Q

structure of oxidative fibres

A

increased O2 delivery and phosphorylation

red fibres with low diameters

33
Q

structure of glycolytic fibres

A

increased glycolytic enzymes and glycogen

white fibres with a large diameter

34
Q

3 types of muscle fibres

A

slow oxidative (I)

fast oxidative (IIa)

fast glycolytic (IIb)

35
Q

slow oxidative fibres (I)

A

resist fatigue

36
Q

fast oxidative fibres (IIa)

A

intermediate resistance to fatigue

37
Q

fast glycolytic fibres (IIb)

A

fatigue quickly

38
Q

increased number of active motor units

A

recuitment

39
Q

order of recruitment

A

slow oxidative

then fast oxidative

then fast glycolytic

40
Q

naural control of motor units depends on

A

frequency of action potentials to motor units

recruitment of motor units

41
Q

what does aerobic exercise increase

A

mitochondria

vascularisation

fibre diameter

42
Q

what does anaerobic exercise increase

A

diameter and glycolysis

43
Q

in smooth muscle cycle, what does ATP do

A

makes binding

44
Q

what does calcium bind to in cycle of smooth muscle

A

calmodulin

45
Q

in skeletal muscle 1 action potential…

A

released enough Ca2+ to saturate ALL troponin sites

46
Q

in smooth muscle 1 action potential…

A

only activates SOME troponin sites

so contractions can be graded

47
Q

smooth muscle always has

A

tone- constant level of Ca2+ to keep a constant tension

48
Q

smooth muscle types

A

single or multi unit

49
Q

simgle unit smooth muscle

A
  • many cells with gap junctions
  • contractions in synch
  • has pacemaker cells
  • stretch evokes contraction
50
Q

single unit muscle is found in

A

GIT, uterus, small blood vessels

51
Q

multiunit smooth muscle

A
  • few or no gap junctions
  • richly innervated
  • doesn’t respond to stretch
52
Q

multi unit smooth muscle can be found in

A

airways, large arteries, hairs