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Bio 223 > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

Where are the myosin filaments anchored

A

the M line

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2
Q

What is a triad made out of?

A

sarcoplasmic reticulum, t tube, sarcoplasmic retitculum

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3
Q

What are the characteristics of myofilaments?

A

made up of actin (thin) myosin (thick)

laidown parallel to one another, slide past
one single bundle/unit of myofilaments, a sarcomere can produce a contraction

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4
Q

muscle is made up of

A

muscle bundles

surrounded by epimysium

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5
Q

muscle bundles are made up of

A

muscle fibers

surrounded by Perimysium

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6
Q

muscle fibers (muscle cell) are made up of

A

muscle fibrils

surrounded by Endomysium

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7
Q

muscle fibrils are made up of

A

sarcomeres

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8
Q

sarcomeres are made up of

A

muscle filaments

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9
Q

muscle filaments are made up of

A

proteins

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10
Q

what are the general functions of muscle?

A 
movement/stability of somatopleure
movement of splanchopleure
heat production
coelomic pressurization
heart beat
structural intergrity of blood vessels, control dilation
communicatio
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11
Q

chain of anatomy of a muscle

A

muscle-muscle bundle-muscle fiber(muscle cell)-myofibrils-sarcomere-muscle filament- protein

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12
Q

what is the plasma membrane of the cell called?

A

sarcolemma

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13
Q

what are myofibrils and what are their characteristics?

A

myofibrils, grouped with one another within a cell

  • working units of a muscle cell
  • gives it the striated look
  • made up of sarcomeres that are laid end to end, made up of myofilaments
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14
Q

describe coelomic pressurization, a function of the muscle

A

for ventilazation

-it increases volume in the ribs, space to breathe

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15
Q

each myofibril within a muscle cell is surrounded by a network of

A

tubes and sacs

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16
Q

what is a sarcoplasmic reticulum

A

network = specialized membrane-bound organelle called

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17
Q

what do tubes and sacs do?

A

these tubes & sacs transmit the continuation of the nerve impulse to the muscle cell.

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18
Q

smallest functional unit of a muscle

A

sarcomere

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19
Q

what filament twist together?

A

actin

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20
Q

thick filaments

A

group of myosin proteins

has heads and tails, heads bundeled together

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21
Q

middle of a sarcomere

A

M line

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22
Q

what do tubes and sacs do for a muscle cell?

A

each one of the myofibrils is surrounded by a network tubes and sacs
going to transmit an action potential thats been generated on the outside of the cell on the sarcomlemma, and its going to carry that action potential down into the cell, into the interior

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23
Q

actin filaments are anchored on?

A

z line, dont connect the same on the other side of the sarcomere

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24
Q

T (transverse) tubules run which way?

A

transvere, to the sarcolemma, surface into the cell

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25
Q

T tubules are associated with what

A

the Z line

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26
Q

what’s special about the sarcoplasmic reticulum? near T Tubules

A

calcium ions inside of it This is stored in enlarged sections, known as terminal cisternae, bracketing T-tubules
**not a sight of calicum storage

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27
Q

what are terminal cisternae?

A

bracketing T-tubules, contains Ca 2+ .calcium ions inside of it This is stored in enlarged sections

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28
Q

steps of an action potential in a muscle cell

A
  1. transverse tubules run into right angles from the sarcolemma
  2. sarcoplasmic reticulium deep into the muscle cell then it connects to the sarcoplasmic reticulium
  3. it does this because when you depolarize the sarcolemma, a neurotransmitter has been release from a neuron and its going to bind to receptors onto the muscle cell
  4. if it’s a big enough stimulus it will depolairize that region and will create an action potential that will be propigated along the sarcolemma,
  5. when that action potential reaches the T Tubules opening into the sarcolemma, then the T tubules will carry that action potential down through the T tubules
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29
Q

neuromuscular junction

A

The portion where the neuron is communicating with the muscle cell
where you’re actually going to send the neurotransmiters from the neuron into the muscle cell

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30
Q

motor unit

A

many muscle fibers (muscles cells) may be innervated by one motor neuron

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31
Q

actual spot spot of communication is called the

A

motor endplate

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32
Q

acetylcholine

A

As with typical neuron, Ca2+ floods into the terminal end of neuron at NM-junction, releasing a neurotransmitter
-released by calcium

33
Q

how acetylcholine causes an action potential

A
  1. acet. crosses the gap and then bind to receptors on the muscle cell, open up chemically gated ion channels which is the stimulus
  2. if enough neurotransmitter has been released, causehuge graded potentional, then causes volated gate on the sarcolemma to reach threshold membrane potential for that volatge gate channel
  3. when it does reachaction potential,will be propigated along the sarcolemma, it will deporlize that section of the motor end plate will create an action potential on the sarcolemma
  4. the action potential travels along the sarcolemma until it reaches the T Tubules and then its carried down into the cell to reach sarcoplasmic reticulum, releases calcium into the cell
    - action potential allows cell to release calcium goes into the myofibril because sarcoplasmic reticulum surrounds it
34
Q

action potential

A

action potential along the sarcolemma, t tubules, until it reaches the sarcoplasmic reticulum

35
Q

sarcoplasmic ret.

A

releases calcium into myofibril

36
Q

z-line

A

endplate of each sarcomere is called a, thinner actin attaches to these endplates

37
Q

myosin is

A

laid down between the actin, parallel to actin

38
Q

I Band

A

portion of the actin that doesn’t overlap with myosin shows up as lighter looking,

39
Q

A Band

A

where myosin exists, overlap and no overlap, beginning of myosin to the end, darker bc thick

40
Q

H Band

A

no overlap, nothing but myosin

41
Q

zone of overlap

A

is the portion of the a-band outside of the h-band in which the thick and thin filaments overlap.

42
Q

triad

A

t-tubules and the adjacent terminal cisternae from sarc retic. form a structure

43
Q

triads are located

A

at the zones of overlap of the sarcomere

relating back to action potential, terminal cisternae, t tubules, to sarc. retic where calcium releaes

44
Q

troponin does what?

A

prevents complete attachment of myosin heads touching actin, blocjs active site

45
Q

sliding filament model facts pt. 1

A

MYOSIN has a tail and a head.
The tail is bound together with other myosin tails to form a thick filament
The head is sticking out and facing the thin filaments
When a myosin head rocks back toward the M-line, it attaches to the ACTIN filament, forming a CROSS-BRIDGE.

46
Q

cross-bridge

A

When a myosin head rocks back toward the M-line, it attaches to the ACTIN filament , head will rock towards the tail

47
Q

tropomyosin

A

Troponin is laced around the actin in a spiral-like manner by a structural protein, holds it

48
Q

Troponin-Tropomyosin complex

A

blocks the complete attachment of myosin and thus the formation of a cross bridge

49
Q

what happens when a cross bridge is formed?

A

natural tendendy of the myosin is to rock backwards towards the M line , but troponin is blocking

50
Q

what is the natural state of filaments?

A

the myosin heads want to rock back on themselves, forming cross-bridges and causing the filaments to slide past one another.

51
Q

when the cross bridge takes place, myosin?

A

brings/ grabs actin towards the M line, the contraction is the actin sliding over closer, takes actin from both sides, shortens sarcomere and brings z-line closer together

52
Q

what is basically a contraction?

A

bringing the z-line closer, bringing the M line closer

53
Q

action potential

A

sarcolemma->down t Tubules-> triad (terminal cist)-> releases calcium to zone of overlap where filaments are sliding past each other

54
Q

what happens when the Ca2+ floods in and the Ca2+ ions bind to the troponin?

A

changes the shape of the troponin-tropomyosin complex enough to move it out of the way enough to allow the cross bridges to form and the myosin heads to rock backwards
-works like a rope, relax the braid, fibers move away from each other

55
Q

a contraction happens when specifically

A

when myosin causes actin to slide past each other, shortening the sarcomere, and thus the muscle of which it is a part , happens every single zone of overlap
when heads form cross bridges towards m line= contraction

56
Q

what happens at the end of the process when calcium is moved away?

A

is pumped back to the sarcoplasmic reticulum, the troponin-tropomyosin complex can again form a barrier.

57
Q

what takes energy in a muscle cell and what does not?

A

does not:cross bridges, myosin heads to rock towards m line

takes energy: to reset them so they can do it again, consume ATP to reset myosin heads

58
Q

what happens when you die to your muscles?

A

no ATP is available, you can’t move (rigor mortis)
-sacroplasmic reticulum will release calcium as it breaks down, which will move troponin out of the way which will make you contract but not reset the myosin, rigor mortis, takes awhile to break down sarc. reticulum can’t reset, eventually lose rigor mortis, break down cross bridges so your muscles are relaxed again

59
Q

what happens when you flood calcium into your myofibrils?

A

cause active sites to remain open until they are cleared out , once calcium back to sarcomplasmic reticlum active sites are blocked, ATP relax myosin heads, muscle will relax

60
Q

what does the length-tension relationship depend on?

A

Depends on the orientation of the myofilaments

Depends on the number of cross-bridges formed

61
Q

what happens when you shorten?

A

can disrupt the 3-D orientation of the filaments, leading to less cross-bridges , myosin heads cannot make as much contract by over shortening, too short not going to generate maximum force

62
Q

what happens in terms of lengthning?

A

can reduce the zone of overlap, leading to less cross-bridges ,reducing the amount of tension and force

63
Q

middle ground is when

A

you can generate the most force and tension, when overlaps are not to short or long

64
Q

Cardiocytes

A

essentially the same as striated, skeletal muscle
uninucleated w/ branching muscle cells
short, broad T-tubules lacking triads and located at the Z-lines rather than zone of overlap
no triads, ttubules on z line

65
Q

big differences of cardiac muscle tissue

A
  • sarcoplasmic reticulum lacks terminal cisternae, no triad and contacts the sarcolemma,
  • sarcolemma is permeable to extracellular calcium, can come outside and can go into the cell itself not having to be released from sarc. retic unlike skeletal
66
Q

intercalated disc in cardiac muscle tissue

A
  • sarcolemmas of adjacent discs are interdigitating and connected by gap junctions
  • important bc gap junctions signal to cell allow to pass cell from one cell don’t need neuron, can coordinate cardiocytes
  • signal can travel directly from cell to cell, essentially causing the muscle to act like a single cell (coordinated). , contract smooth wave from one wave to another,
67
Q

whats important in cardiac muscle

A

external to myofilament, myofibirils, t tubules are different, no terminal cisternae, sarcoriticulum can reach and touch sarcolemma

68
Q

cardiocytes (automaticity or (autorhythmicity)

A

rhythm of it is automatic, dont need to send a signal
due to prepotential (pacemaker potential)
-

69
Q

prepotential (pacemaker potential)

A
  • specialized cardiac muscle cells that contain very little myofibrils. —–these are called the Conducting System or Nodal System (like nerves)
  • this includes the sinoatrial node, atrioventricular node and the conducting cells.
70
Q

The cells of the sinoatrial and atrioventricular nodes are

A

“leaky” and allow sodium to slowly enter the cell, don’t keep sodium out at a constant rate, once it has repolarized these cells of the nodes will allow sodium to leak, when sodium enters the cell The membrane potential gradually rises toward threshold and spontaneously generates a depolarization, the nervous system is not required to generate action potentials, only to regulate them. Even if no neural signal, reach thereshold by itself, cause contration of heart, why heart does not require nervous system to set heart rate

71
Q

nervous singnals in terms of cardiac muscle

A

Nervous signals, modify this heart rate to speed or slow
doesn’t require those signals to beat or have a set heart rate
nervous signals, only purpose to regulate and modify those things

72
Q

where is smooth muscle located?

A

located in the walls forming sphincters for the digestive and urinary systems 0f the viscera and blood vessels as well as and within the eyes inside actually globe of eye , NOT in heart

73
Q

characteristics of smooth muscle

A
  • the fibers are long and slender, tapering like a football. This is called fusiform, spindle shaped
  • lacks T-tubules and lack sarcoplasmic reticulum is in the form of a loose network, not in triads or anything like that, spread out in the cell
  • respond to ANS, still have actin and myosin, they are spread out in a fishnet stocking arrangment rather than sarcomeres arrangment and overlapping
74
Q

thick filaments in smooth muscle

A

thick filaments are scattered throughout the sarcoplasm and have more myosin heads per filament

75
Q

dense bodies in smooth muscle

A

thin filaments are attached to Dense Bodies, which are scattered throughout the sarcoplasm and attached to the sarcolemma

  • Thin filament, dense bodies, where X’s cross over
  • That’s where actin is attached
  • dense bodies-connect one cell to another, X shape, contract X’s together
76
Q

filaments in smooth muscle

A
  • when the filaments slide past each other, the cell shortens by twisting like a corkscrew, does not show striations
  • dense bodies connect one cell to another transmitting force from cell to cell, coordinating contraction
77
Q

unlike striated muscle, smooth muscle

A

combines to calmodulin(unlike troponin), which activates Myosin Light Chain Kinase

78
Q

Myosin Light Chain Kinase, (smooth muscle)

A

The kinase allows cross bridges to form, thus initiating contraction.

79
Q

Plasticity in smooth muscle

A

unlike striated muscle, smooth muscle can stretch and adapt to the new length. This is a result of the arrangement of the myofilaments. This allows smooth muscle to retain function even when stretched, as in the walls of the digestive tract.

  • no length muscle tension curve
  • when muscles stretch out, they still work will because of plasticity

Bio 223 (8 decks)

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