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Fundamentals Of Science > Muscle Contraction > Flashcards

Muscle Contraction Flashcards

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Biology 101 flashcards
1
Q

Structure of skeletal

A

Striated, long, contain many nuclei and mitochondria

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2
Q

Structure of cardiac

A

striated, only one nucleus

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3
Q

Structure of smooth muscle

A

single nucleus, no t tubule system, irregular arrangement

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4
Q

t tubule system is

A

structural system of membrane folds characteristic of skeletal and cardiac muscle

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5
Q

ryanodine receptors are

A

calcium release channels in the sarcoplasmic reticulum

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6
Q

troponin is

A

calcium sensor in skeletal and cardiac muscle

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7
Q

tropomyosin is

A

protein associated with actin that prevents myosin binding

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8
Q

calmodulin

A

calcium sensor in smooth muscle cells

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9
Q

myosin light chain kinase (MLCK)

A

activated by calcium-calmodulin that converts smooth muscle myosin to more active form

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10
Q

organisation of skeletal muscle

A

-organised as group of bundles (fasciles).
-each fascile has many muscle cells (known as muscle fibre)
-within the muscle fibre (single cell), contains contractile units

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11
Q

neuromuscular junction (NMJ)

A

a synaptic connection between the terminal end of a motor nerve and a muscle

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12
Q

ACh is released and binds to receptor on muscle membrane. what happens when it reaches receptors?

A

-membrane channels open and contraction of relaxed muscle fibres begin

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13
Q

opening of what ion channels causes depolarisation?

A

sodium ion

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14
Q

ACh containing vesicles fuses with membrane. what is released and where does it bind?

A

acetylcholine is released and diffuses a short distance binding to nAChR

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15
Q

When do muscle fibres relax?

A

when nervous system signal is no longer present

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16
Q

one sarcomere runs from

A

one z disc to the next

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17
Q

thick filaments contain

A

mysoin

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18
Q

thin filaments contain

A

actin

19
Q

sarcoplasmic reticulum is

A

big energy store for calcium
surrounds each myofibril

20
Q

mechanism behind muscle contraction

A
21
Q

role of myosin ATPase

A

allows myosin to consume ATP and convert it into ADP and pi

22
Q

sliding filament model

A
  • Both in skeletal and cardiac muscle rise in calcium will bind to troponin and remove tropomyosin from the myosin binding site on actin leaving them exposed
  • Allows myosin head (on myosin filament), with hydrolysed ATP to then bind leading to power stroke when ADP released
    -More ATP binding will cause detachment of myosin head and the subsequent hydrolysis will cause shape of myosin to change and move along another actin binding site
  • Causes muscle cell to shorten and contract
23
Q

summarise muscle contraction

A
  • Neuron AP leads to ca2+ influx
    -ACh released
    -Activate nAChR
  • Depolarisation open voltage gated Na+ ion channel
    -T-tubule dihydropyridine activated
    -Calcium released
    -Calcium binds to troponin
    -Sliding filament model
24
Q

V SNAREs found in

A

vesicles

25
Q

T SNAREs found in

A

cell membrane

26
Q

Two main types of T SNAREs

A

syntax-1 and SNAP 25

27
Q

How is a SNARE PIN created?

A

-Rise in calcium, Ca2+ binds to synaptotagamin
- The SNAP has higher afinity for phospholipids and stops interacting with VSNARE
-brings vesicle a little closer, allowing VSNARE (synaptobrevin) to interact with the TSNARE

28
Q

what effect does botox have on SNAREs

A

degrades VSNARE/ TSNARE so vesicle for ACh cannot fuse

29
Q

what is synaptotagamin?

A

calcium sensor

30
Q

role of sarcoplasmic reticulum

A

big calcium store

31
Q

function of ryanodine receptor, RyR

A

Calcium release channel, suppresses the opening and stops leak of calcium

32
Q

mechanism for calcium release out of RyR

A
  • activated of nAChR
    -opening of voltage sodium channels
    -passes excitation down the t tubules
    -activated DHPR
  • molecular change thats caused, removes physical interaction
33
Q

CICR

A

calcium induced calcium release

34
Q

function of CICR

A

calcium influx induces RyR to release calcium

34
Q

function of CICR

A

calcium influx induces RyR to release calcium

35
Q

Summarise muscle contraction

A
  • Neuronal A.P leads to calcium influx
    -ACh release
    activates nAChr
    -depolarisation open voltage-gated Na+ channel
  • t-tubule DHP activated
  • Calcium release
    -Calcium ions bind to troponin, leading to removal
    of inhibitory tropomyosin
    -ATP hydrolysis by myosin
    -This primed myosin binds to actin
    -As ADP released , it moves the actin towards the middle of the cell leading to cell shortening
36
Q

difference between skeletal and cardiac for excitation through t tubules

A

skeletal- voltage sensitive DHP protein leads to calcium release from SarcR
Cardiac- voltage- sensitive calcium channel leads to CICR from SR

37
Q

What happens in the contractile cycle?

A

-Cross bridge formation releases pi
troponin bind to myosin head
-power stroke, ADP is released and myosin undergoes a conformational change
pulled towards centre of sarcomere
-ATP binds to myosin, causing detachment of myosin from actin, cross-bridge dissociates
-ATP hydrolysis occurs, cocking myosin head

38
Q

T-tubule define:

A

structural system of membrane folds characteristic of skeletal and cardiac muscle

39
Q

Ryanodine receptors define :

A

calcium release channels in the sarcoplasmic reticulum

40
Q

Troponin define:

A

calcium sensor in skeletal and cardiac muscle

41
Q

tropomyosin define:

A

A protein associated with actin that prevents myosin binding

42
Q

calmodulin define:

A

calcium sensor in smooth muscle cells

43
Q

Myosin Light Chain Kinase (MLCK) define:

A

Activated by calcium-calmodulin that converts smooth muscle myosin to a more active form

Fundamentals Of Science (37 decks)

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